2009 Vol. 27, No. 5
Display Method:
2009, 27(5): 777-786.
Abstract:
This paper reviewed the advances and achievements over the past thirty years of the Society of Mineralogy, Petrology and Geochemistry (SMPG), Committee of Sedimentology (COS) and Committee of Sedimentary Geology (CSG) established in 1979 in China. Main contents involved in this paper include the establishment background of the committees and evolution of their organization framework; information about the conferences related to sedimentology hosted by the committees at home and abroad, which enhanced the academic progress in this field; more efforts focused on the international activities and put forward the exchange and development with the equivalent international organizations; Issued the academic journal Acta Sedimentologica Sinica which become one of important academic exchange platform within China over past twenty eight years.
This paper reviewed the advances and achievements over the past thirty years of the Society of Mineralogy, Petrology and Geochemistry (SMPG), Committee of Sedimentology (COS) and Committee of Sedimentary Geology (CSG) established in 1979 in China. Main contents involved in this paper include the establishment background of the committees and evolution of their organization framework; information about the conferences related to sedimentology hosted by the committees at home and abroad, which enhanced the academic progress in this field; more efforts focused on the international activities and put forward the exchange and development with the equivalent international organizations; Issued the academic journal Acta Sedimentologica Sinica which become one of important academic exchange platform within China over past twenty eight years.
2009, 27(5): 787-791.
Abstract:
In 1960s of the last century, due to the introduction of physicochemical kinetics and fiacies equilibrium of minerals under low temperature and low pressure conditions, the study on sedimentary diagenesis has achieved obvious breakthroughs and advances; in the meantime, the organic geochemistry also enhanced the research on the sedimentary diagenesis. At present, the study on the sedimentary diagenesis has become the integrated research with wide scales and multi disciplines including tectonics, basin analysis, sedimentology, physiochemistry and organic geochemistry, and so on. The great demands on petroleum and solid mineral resources have provided the impetus to the deep research on the sedimentary diagenesis. And, the geological processes such as petroleum formation and accumulation, variation of reservoir properties are all involved in the sedimentary diagenesis; the enrichment of some stratigraphicallycontrolled mineral deposits is related to the basin fillings, conversion of basin-mountain lithofacies as well as dynamics of fluid flow and physicochemical behavior. Since 1970s, all these researches have gained considerable achievements. In recent years, investigations on the diagenetic processes relevant to marine sedimentation, silicon, Mn and carbonate sediments, tectonic background, isotopes, organism evolution have also gotten important advances and become hotspots in these fields.
In 1960s of the last century, due to the introduction of physicochemical kinetics and fiacies equilibrium of minerals under low temperature and low pressure conditions, the study on sedimentary diagenesis has achieved obvious breakthroughs and advances; in the meantime, the organic geochemistry also enhanced the research on the sedimentary diagenesis. At present, the study on the sedimentary diagenesis has become the integrated research with wide scales and multi disciplines including tectonics, basin analysis, sedimentology, physiochemistry and organic geochemistry, and so on. The great demands on petroleum and solid mineral resources have provided the impetus to the deep research on the sedimentary diagenesis. And, the geological processes such as petroleum formation and accumulation, variation of reservoir properties are all involved in the sedimentary diagenesis; the enrichment of some stratigraphicallycontrolled mineral deposits is related to the basin fillings, conversion of basin-mountain lithofacies as well as dynamics of fluid flow and physicochemical behavior. Since 1970s, all these researches have gained considerable achievements. In recent years, investigations on the diagenetic processes relevant to marine sedimentation, silicon, Mn and carbonate sediments, tectonic background, isotopes, organism evolution have also gotten important advances and become hotspots in these fields.
2009, 27(5): 811-817.
Abstract:
The clustered continents of South China (CCSC) is a group of Early Paleozoic continental blocks including the Yangtze block, the Wuyi block, and the Yunkai block. The CCSC and its surrounding sea compose an archipelago. The CCSC was located in northern margin of Gondwana during the Early Paleozoic and collaged to Eurasia during the Late Paleozoic and the Early Mesozoic. The tectonics of the CCSC is characterized by small size, later collage, weak extension, and strong compression, while the innercontinental deformation of the CCSC is characterized by multiple engine and wide range. Some important unanswered questions include: (1) has ever been an oceanic basin between the Yangtze and the Cathaysia blocks? What is the nature of sedimentation of the CCSC? (2) What is the impact of the Late Paleozoic extension on changes of paleoenvironment and paleogeography of the CCSC? (3) What is the sedimentary response to the innercontinental deformation of the CCSC? Approaching to these questions will help understanding geodynamics of the South China and accumulating knowledge of continental dynamics.
The clustered continents of South China (CCSC) is a group of Early Paleozoic continental blocks including the Yangtze block, the Wuyi block, and the Yunkai block. The CCSC and its surrounding sea compose an archipelago. The CCSC was located in northern margin of Gondwana during the Early Paleozoic and collaged to Eurasia during the Late Paleozoic and the Early Mesozoic. The tectonics of the CCSC is characterized by small size, later collage, weak extension, and strong compression, while the innercontinental deformation of the CCSC is characterized by multiple engine and wide range. Some important unanswered questions include: (1) has ever been an oceanic basin between the Yangtze and the Cathaysia blocks? What is the nature of sedimentation of the CCSC? (2) What is the impact of the Late Paleozoic extension on changes of paleoenvironment and paleogeography of the CCSC? (3) What is the sedimentary response to the innercontinental deformation of the CCSC? Approaching to these questions will help understanding geodynamics of the South China and accumulating knowledge of continental dynamics.
2009, 27(5): 826-836.
Abstract:
For a long time sedimentlogists have used grain size parameters as a critierion to determine the type of sedimentary environments or to identify the mode of transport before accumulation. However, such efforts have been only partly successful. Another possible ussage of grain size data is to delineate sediment transport pathways on the basis of the spatial distribution paterns of grain size parameters, which is defined as “grain size trends”. Based upon analysis of grain size trends, qualitative models for sediment transport have been established. The basic scientific problems for grain size trend analysis include: the procedure to subtract the information on transport; the method to determine which types of the trends contain transport information; and the conditions under which the method can be applied. For the first two questions, it has been proposed that the patterns of the trends can be obtained by defining the “trend vector” and identifying its spatial anisotropy (the significance of which can be tested using statistical methods), and empirical evidence has shown the existence of the trend types that contain transport information. With regard to the third question, preliminary studies indicate that the following conditions should be satisfied for the application of grain size trend analysis: (1) the spatial anisotropy of the trend vectors is statistically significant; (2) the sampling depth matches the temporal scale of the transport phenomenon; (3) the sampling interval is in agreement with the geostatistical principle; (4) the edge effect is eliminated; and (5) the samples are from the same transport system or the sedimentary environment is in an accretional status. However, these conditions are still incomplete, because of the uncertainties from the effects of material mixing, the characteristics and their changes of sediment in source areas, transport in different hydrodynamic settings, settling processes of suspended sediment, transformation between dissolvedparticulate materials and lateral distribution patterns of sediment movement. A thorough solution to the problem depends upon future progress in the study of the processes and mechanisms for the formation of grain size trends
For a long time sedimentlogists have used grain size parameters as a critierion to determine the type of sedimentary environments or to identify the mode of transport before accumulation. However, such efforts have been only partly successful. Another possible ussage of grain size data is to delineate sediment transport pathways on the basis of the spatial distribution paterns of grain size parameters, which is defined as “grain size trends”. Based upon analysis of grain size trends, qualitative models for sediment transport have been established. The basic scientific problems for grain size trend analysis include: the procedure to subtract the information on transport; the method to determine which types of the trends contain transport information; and the conditions under which the method can be applied. For the first two questions, it has been proposed that the patterns of the trends can be obtained by defining the “trend vector” and identifying its spatial anisotropy (the significance of which can be tested using statistical methods), and empirical evidence has shown the existence of the trend types that contain transport information. With regard to the third question, preliminary studies indicate that the following conditions should be satisfied for the application of grain size trend analysis: (1) the spatial anisotropy of the trend vectors is statistically significant; (2) the sampling depth matches the temporal scale of the transport phenomenon; (3) the sampling interval is in agreement with the geostatistical principle; (4) the edge effect is eliminated; and (5) the samples are from the same transport system or the sedimentary environment is in an accretional status. However, these conditions are still incomplete, because of the uncertainties from the effects of material mixing, the characteristics and their changes of sediment in source areas, transport in different hydrodynamic settings, settling processes of suspended sediment, transformation between dissolvedparticulate materials and lateral distribution patterns of sediment movement. A thorough solution to the problem depends upon future progress in the study of the processes and mechanisms for the formation of grain size trends
2009, 27(5): 849-862.
Abstract:
〗aphic unit can be usually classified into several types of genetic deposits, that is, the normal regressive, forced regressive, transgressive and aggradational deposits. Depositional cycle of a third order sThe development of modern sequence stratigraphic theories, integrating the study of depositional process in the time and space configuration and the cyclic or rhythmic evolution of the Earth, has formed a innovative theory for the investigation of depositional facies in chronostratigraphic framework, and became an important prospecting tool for petroleum exploration. Basin fills can be usually divided into different sequence stratigraphic units consistence with different cycles. The regional sequence stratigraphic framework established by collating highorder sequence stratigraphic units confined by major unconformities is very important for the reconstruction of tectonopaleogeography and the strategic evaluation of petroleum exploration, and the high resolution sequence stratigraphic framework erected by tracing the low order, such as the forth or fifth odor sequence stratigraphic units, may provide accurate stratigraphic correlation for the investigation of depositional facies and reservoir distribution along selected districts within a basin. Depositional cycle of a sequence stratigrequence stratigraphic unit can be easily divided into lowstand, transgressive, highstand and falling systems tracts in marine or nonmarine basins.
The control of tectonism, climatic and sea or lake level change on the development of depositional sequences has long been one of the major research themes in sequence stratigraphy or sedimentological geology. The evolution of basin filling sequence is the response to the basin dynamic processes. The combination study of sequence stratigraphy with basin dynamic or regional evolution of the Earth has formed an important research area intaking the study of paleotectonics and paleogeography into the unique time and space system of the Earth evolution. The multiple reformation of the polycyclic or superimposed basins underwent resulted in the stacking of a series of tectonic sequences confined by regional unconformities and it is the key to establish the relationship of the tectonic evolution and the basin filling sequence in order to reveal the sedimentary geological history and petroleum accumulation within a basin. The formation of major unconformities and regional depositional cycles or sequences are commonly attributed to the tectonism, such as the multiple thrust flexural subsidence and rebounding uplift due to denudation, multiple riffing and tectonic reversion; whereas the development of high frequency depositional sequences related to sea or lake level change have be usually interpreted to be controlled by climatic change. In the tectonic actively basins, the structural slopbreak zones have great influence on the development of despositional systems tracts and facies associations.
〗aphic unit can be usually classified into several types of genetic deposits, that is, the normal regressive, forced regressive, transgressive and aggradational deposits. Depositional cycle of a third order sThe development of modern sequence stratigraphic theories, integrating the study of depositional process in the time and space configuration and the cyclic or rhythmic evolution of the Earth, has formed a innovative theory for the investigation of depositional facies in chronostratigraphic framework, and became an important prospecting tool for petroleum exploration. Basin fills can be usually divided into different sequence stratigraphic units consistence with different cycles. The regional sequence stratigraphic framework established by collating highorder sequence stratigraphic units confined by major unconformities is very important for the reconstruction of tectonopaleogeography and the strategic evaluation of petroleum exploration, and the high resolution sequence stratigraphic framework erected by tracing the low order, such as the forth or fifth odor sequence stratigraphic units, may provide accurate stratigraphic correlation for the investigation of depositional facies and reservoir distribution along selected districts within a basin. Depositional cycle of a sequence stratigrequence stratigraphic unit can be easily divided into lowstand, transgressive, highstand and falling systems tracts in marine or nonmarine basins.
The control of tectonism, climatic and sea or lake level change on the development of depositional sequences has long been one of the major research themes in sequence stratigraphy or sedimentological geology. The evolution of basin filling sequence is the response to the basin dynamic processes. The combination study of sequence stratigraphy with basin dynamic or regional evolution of the Earth has formed an important research area intaking the study of paleotectonics and paleogeography into the unique time and space system of the Earth evolution. The multiple reformation of the polycyclic or superimposed basins underwent resulted in the stacking of a series of tectonic sequences confined by regional unconformities and it is the key to establish the relationship of the tectonic evolution and the basin filling sequence in order to reveal the sedimentary geological history and petroleum accumulation within a basin. The formation of major unconformities and regional depositional cycles or sequences are commonly attributed to the tectonism, such as the multiple thrust flexural subsidence and rebounding uplift due to denudation, multiple riffing and tectonic reversion; whereas the development of high frequency depositional sequences related to sea or lake level change have be usually interpreted to be controlled by climatic change. In the tectonic actively basins, the structural slopbreak zones have great influence on the development of despositional systems tracts and facies associations.
2009, 27(5): 872-879.
Abstract:
Three main characteristics of ancient earthquakes are demonstrated in this paper. They are macrostructures, microstructures, and geochemical abnormal. There are differences of earthquake records in various lithogeographic environments. It is recognized that the formation factors caused by water escape fillings so called molar tooth structures either in clastic rocks or in carbonate rocks, such as sand liquefaction and sand bed slump structures so common in lacustrine, lagoon and tidal flats but molar tooth structures widely distributed in carbonate rocks related with marine ramp environment due to tempsite beds always containing more water. Besides, volcanic crystals, tuffs, or pseudomorphic volcanic glasses could be company with earthquake records beds need pay attention to collection of samples for geoage determination.
Three main characteristics of ancient earthquakes are demonstrated in this paper. They are macrostructures, microstructures, and geochemical abnormal. There are differences of earthquake records in various lithogeographic environments. It is recognized that the formation factors caused by water escape fillings so called molar tooth structures either in clastic rocks or in carbonate rocks, such as sand liquefaction and sand bed slump structures so common in lacustrine, lagoon and tidal flats but molar tooth structures widely distributed in carbonate rocks related with marine ramp environment due to tempsite beds always containing more water. Besides, volcanic crystals, tuffs, or pseudomorphic volcanic glasses could be company with earthquake records beds need pay attention to collection of samples for geoage determination.
2009, 27(5): 896-903.
Abstract:
Diagenesis plays an important role in reservoir quality. Prediction of chemically diagenetic trend is the key of reservoir evaluation. In order to search after the predicting method for reservoir quality basing on the diagenesis, thermodynamic models of some main kinds of diagenesis affecting porosity and permeability, including dissolution of feldspars, carbonate minerals and calcitedolomite equilibrium, have been constructed. With the help of these models, we can calculate the dissolutionprecipitation trend of diagenetic minerals. Based on these trends, we can analyze the developing extent of secondary pores in clastic reservoirs, karstification and dolomitization in carbonate reservoirs, which provide the geochemical data for the reservoir evolution.
Diagenesis plays an important role in reservoir quality. Prediction of chemically diagenetic trend is the key of reservoir evaluation. In order to search after the predicting method for reservoir quality basing on the diagenesis, thermodynamic models of some main kinds of diagenesis affecting porosity and permeability, including dissolution of feldspars, carbonate minerals and calcitedolomite equilibrium, have been constructed. With the help of these models, we can calculate the dissolutionprecipitation trend of diagenetic minerals. Based on these trends, we can analyze the developing extent of secondary pores in clastic reservoirs, karstification and dolomitization in carbonate reservoirs, which provide the geochemical data for the reservoir evolution.
2009, 27(5): 915-921.
Abstract:
Seismic sedimentology is the use of seismic data to study sedimentary rocks and the processes by which they are formed．It is a new traverse subject which is superior in mapping highfrequency sequences and depositional systems and has got the obvious results in oilgas exploration and development
．We use the techology of the frequency spectrum decomposition and stratal slicing, the key wells＇constraints to facies types, as well as the use of geomorphic features of different sand shapes to start seismic sedimentological studies in a certain basin of Central Asia．By analysising a series of typical stratal slices, we could find that the target zone is mainly subaqueous distributary channel of braided delta, the delta lobes override in vertical profile, thin layer lacustrine mudstone deposit between underwater distributary of braided delta．
Seismic sedimentology is the use of seismic data to study sedimentary rocks and the processes by which they are formed．It is a new traverse subject which is superior in mapping highfrequency sequences and depositional systems and has got the obvious results in oilgas exploration and development
．We use the techology of the frequency spectrum decomposition and stratal slicing, the key wells＇constraints to facies types, as well as the use of geomorphic features of different sand shapes to start seismic sedimentological studies in a certain basin of Central Asia．By analysising a series of typical stratal slices, we could find that the target zone is mainly subaqueous distributary channel of braided delta, the delta lobes override in vertical profile, thin layer lacustrine mudstone deposit between underwater distributary of braided delta．
2009, 27(5): 931-398.
Abstract:
With the application of the principles of sequence stratigraphy， Shahejie formation of Paleogene in Diannan Area is divided into six 3rd order sequences ，seventeen system tracts by the identification marks of sequence boundary including seismic section， well logging curves， lithocombination and so on. Without lowstand systems tract in the sequence Ⅰ,the sequence Ⅱto sequence Ⅵ are all composed of lowstand systems tract, transgressive systems tract and highstand systems tract. Based on the division and correlation of the sequence stratigraphy units two sequence stratigraphic models with different genesis including the fault slopebreak and sedimentary slopebreak are established. The relations between the models and the distinction of lithologic hydrocarbon reservoir indicate that low stand fan and stratigraphic overlap hydrocarbon reservoirs are usually located below the slopebreak， and unconformity， beachdam lens reservoirs are usually located on the top of slopebreak.
With the application of the principles of sequence stratigraphy， Shahejie formation of Paleogene in Diannan Area is divided into six 3rd order sequences ，seventeen system tracts by the identification marks of sequence boundary including seismic section， well logging curves， lithocombination and so on. Without lowstand systems tract in the sequence Ⅰ,the sequence Ⅱto sequence Ⅵ are all composed of lowstand systems tract, transgressive systems tract and highstand systems tract. Based on the division and correlation of the sequence stratigraphy units two sequence stratigraphic models with different genesis including the fault slopebreak and sedimentary slopebreak are established. The relations between the models and the distinction of lithologic hydrocarbon reservoir indicate that low stand fan and stratigraphic overlap hydrocarbon reservoirs are usually located below the slopebreak， and unconformity， beachdam lens reservoirs are usually located on the top of slopebreak.
2009, 27(5): 956-966.
Abstract:
There are some quite different disputes about the provenance types and tectonic attributes of early Cretaceous deposits in Kuqa Subbasin, northern margin of the Tarim Basin, with very complicated source rocks. In order to reveal further detailed information on the nature of the source terrains, a typical sandstone samples from the Yageliemu Formation in early Cretaceous strata is collected for UPb dating of 79 detrital zircons. The lower Cretaceous sample shows a complicated provenance geochronological constitution, with new peak ages of 427~389 Ma, 379~339 Ma, 321~283 Ma, 266~239 Ma, 162~150 Ma and some Precambrian basement zircons. Investigating on the rock attributes and age constitution of the Tian Shan Orogen, the potential source area, together with the previous results of sandstone framwork grains and detrital heavy minerals in Kuqa Subbasin, we suggest that the provenance supply is mainly resulted from denudation process of the South Tian Shan, the granitealkaline rocks belts in South Tian Shan and YiliCentral Tian Shan (including the Paleozoic granites and vocanic rocks at the southern margin of the Central Tian Shan)，related to the MiddleLate Jurassic volcanism and the OrdovicianPermian tectonic events. Additionly，the several clusters of ProterozoicArchean ages of this sample probably reflect that some provenance areas were deeply exhumated and the ArcheanProterozoic basement maybe exsist in the Tian Shan Orogen. In addition，the detrital zircons age spectra of 162～150Ma indicates that there was possible magma activity in late Jurassic in Tian Shan area, which require further work.
There are some quite different disputes about the provenance types and tectonic attributes of early Cretaceous deposits in Kuqa Subbasin, northern margin of the Tarim Basin, with very complicated source rocks. In order to reveal further detailed information on the nature of the source terrains, a typical sandstone samples from the Yageliemu Formation in early Cretaceous strata is collected for UPb dating of 79 detrital zircons. The lower Cretaceous sample shows a complicated provenance geochronological constitution, with new peak ages of 427~389 Ma, 379~339 Ma, 321~283 Ma, 266~239 Ma, 162~150 Ma and some Precambrian basement zircons. Investigating on the rock attributes and age constitution of the Tian Shan Orogen, the potential source area, together with the previous results of sandstone framwork grains and detrital heavy minerals in Kuqa Subbasin, we suggest that the provenance supply is mainly resulted from denudation process of the South Tian Shan, the granitealkaline rocks belts in South Tian Shan and YiliCentral Tian Shan (including the Paleozoic granites and vocanic rocks at the southern margin of the Central Tian Shan)，related to the MiddleLate Jurassic volcanism and the OrdovicianPermian tectonic events. Additionly，the several clusters of ProterozoicArchean ages of this sample probably reflect that some provenance areas were deeply exhumated and the ArcheanProterozoic basement maybe exsist in the Tian Shan Orogen. In addition，the detrital zircons age spectra of 162～150Ma indicates that there was possible magma activity in late Jurassic in Tian Shan area, which require further work.
2009, 27(5): 976-982.
Abstract:
Through analyzing tectonic framework and sequence stratigraphic framework, comparing regional uniform surfaces, Nanpu Sag was compared with other basins in the eastern China, it was sured that strata of Paleogene of Nanpu Sag were related with sedimentary in the third period and fourth period of rifting. On the basis of all of these, it could be divided into 4 subperiodic subsidence through comparing the scale of uniform of different periodic rifting and volcanic activity periods researching. Meanwhile, characteristics of tectonic activity in different periodic rifting and their controlling on sedimentary filling were studied. Periodic rifting activity in Nanpu Sag could be classified into three periods. Sedimentation process was entirely controlled by boundary fault in the first and second period, sedimentary and subsidence were controlled by steppedshaped slope belt in steep slope of the eastern Nanpu Sag in the third period, while Gaoliu fault became marginal fault and controlled sedimentary filling in its downing wall in the fourth period.
Through analyzing tectonic framework and sequence stratigraphic framework, comparing regional uniform surfaces, Nanpu Sag was compared with other basins in the eastern China, it was sured that strata of Paleogene of Nanpu Sag were related with sedimentary in the third period and fourth period of rifting. On the basis of all of these, it could be divided into 4 subperiodic subsidence through comparing the scale of uniform of different periodic rifting and volcanic activity periods researching. Meanwhile, characteristics of tectonic activity in different periodic rifting and their controlling on sedimentary filling were studied. Periodic rifting activity in Nanpu Sag could be classified into three periods. Sedimentation process was entirely controlled by boundary fault in the first and second period, sedimentary and subsidence were controlled by steppedshaped slope belt in steep slope of the eastern Nanpu Sag in the third period, while Gaoliu fault became marginal fault and controlled sedimentary filling in its downing wall in the fourth period.
2009, 27(5): 995-1001.
Abstract:
The oil and gas exploration for oolitic shoals in the Triassic platform margin in Sichuan Basin makes important breakthrough and headway. This has aroused the research interest for shoal body within wide carbonate platform. Taking the Bed A of the Jia2 Member in the Moxi Gas Field in central Sichuan Basin for an object of study, this article summarizes the development characteristics of the intraplatform shoal in the epicontinental carbonate platform, based on the analysis of the data of logging and coring in the region of interest. The intraplatform shoal is characterized by the shallowingupward sequence. A single shoal body is less than 4 meters in the thickness. Besides, the cumulative thickness and horizontal succession are both relatively inferior. The further research proves that the development and distribution of the oolitic shoals within the platform are controlled by the depositional palaeogeomorphology, water depth, turbulent of sea water and fluctuation of sea level. Meanwhile the research also indicates that the inherited palaeohigh within the epicontinental carbonate platform is benefit to develop the shoal vertically and horizontally. However, the palaeogeomorphologic differentiation causes horizontally great variation of intraplatform shoal. All of the investigation has laid a solid geologic foundation for the further exploration.
The oil and gas exploration for oolitic shoals in the Triassic platform margin in Sichuan Basin makes important breakthrough and headway. This has aroused the research interest for shoal body within wide carbonate platform. Taking the Bed A of the Jia2 Member in the Moxi Gas Field in central Sichuan Basin for an object of study, this article summarizes the development characteristics of the intraplatform shoal in the epicontinental carbonate platform, based on the analysis of the data of logging and coring in the region of interest. The intraplatform shoal is characterized by the shallowingupward sequence. A single shoal body is less than 4 meters in the thickness. Besides, the cumulative thickness and horizontal succession are both relatively inferior. The further research proves that the development and distribution of the oolitic shoals within the platform are controlled by the depositional palaeogeomorphology, water depth, turbulent of sea water and fluctuation of sea level. Meanwhile the research also indicates that the inherited palaeohigh within the epicontinental carbonate platform is benefit to develop the shoal vertically and horizontally. However, the palaeogeomorphologic differentiation causes horizontally great variation of intraplatform shoal. All of the investigation has laid a solid geologic foundation for the further exploration.
2009, 27(5): 1012-1017.
Abstract:
Syndepositional deformation structures were well developed in the Fei 1 Member nearby the Hua Yingshan fracture belt in the eastern Sichuan Basin. Based on studies of regional tectonic setting and observation of geologic crosssections and drilling cores, it is concluded that these structures, such as liquefied vein, gravity fault, bedding phenomenon, enterolithic structure, flamme structure, convolute beddings were mainly produced by seismic liquefaction. According to recognition marks and combination characteristics, seismic sedimentary process can be divided into autochthonous seismite(A), tsunamite(B) and background deposit(C) units, of which unit A consist of liquefied vein(a), seismic corrugated rock(b) and shattering rock, which are associated into two types of associations: abc(A1) and bc(A2). The sedimentary sequence of seismite of the Fei 1 Member in the eastern Sichuan Basin is A1BA2C. Combining with the cognizance of regional tectonic setting, it indicates that the seismite is in connection with the Hua Yingshan fracture belt, and the seismic activities due to the activities of the Hua Yingshan fracture belt provided dynamics for the developing of seismite of the Fei 1 Member in the eastern Sichuan Basin.
Syndepositional deformation structures were well developed in the Fei 1 Member nearby the Hua Yingshan fracture belt in the eastern Sichuan Basin. Based on studies of regional tectonic setting and observation of geologic crosssections and drilling cores, it is concluded that these structures, such as liquefied vein, gravity fault, bedding phenomenon, enterolithic structure, flamme structure, convolute beddings were mainly produced by seismic liquefaction. According to recognition marks and combination characteristics, seismic sedimentary process can be divided into autochthonous seismite(A), tsunamite(B) and background deposit(C) units, of which unit A consist of liquefied vein(a), seismic corrugated rock(b) and shattering rock, which are associated into two types of associations: abc(A1) and bc(A2). The sedimentary sequence of seismite of the Fei 1 Member in the eastern Sichuan Basin is A1BA2C. Combining with the cognizance of regional tectonic setting, it indicates that the seismite is in connection with the Hua Yingshan fracture belt, and the seismic activities due to the activities of the Hua Yingshan fracture belt provided dynamics for the developing of seismite of the Fei 1 Member in the eastern Sichuan Basin.
2009, 27(5): 792-810.
Abstract:
Global climate change is represented by a significant warming in the past 100 years. Human civilization is faced with an increasing urgency to understand global climate change and its potential effects on ecosystems, resources and habitability. It is limited to focus on modern and Quaternary climate researches. The path to understanding earth's climate system demands a fully integrated exploration of the earth in the geological history. Deep Time will study climate changes and main geological events using sedimentary records in the preQuaternarey, so as to provide information for predicting the future climate. Deep Time focuses key scientific questions in Earth's climate system, discusses thresholds and rates of climate changes, atmospheric and oceanic composition, atmospheric and oceanic circulation, linkages with the biosphere, solid earth and sun, and finally reveals the relationship between earth's climate system and earth's surface system. The goal of Deep Time is to read, date and model earth's past climate system. To achieve this, development of a continental drilling program to enable acquisition and preservation of continuous, highresolution datasets is the most important. It is predictable that Deep Time together with Deep Space, Deep Sea and Deep Interior will be new fields in Geosciences. Sedimentology will play a core role in Deep Time research.
Global climate change is represented by a significant warming in the past 100 years. Human civilization is faced with an increasing urgency to understand global climate change and its potential effects on ecosystems, resources and habitability. It is limited to focus on modern and Quaternary climate researches. The path to understanding earth's climate system demands a fully integrated exploration of the earth in the geological history. Deep Time will study climate changes and main geological events using sedimentary records in the preQuaternarey, so as to provide information for predicting the future climate. Deep Time focuses key scientific questions in Earth's climate system, discusses thresholds and rates of climate changes, atmospheric and oceanic composition, atmospheric and oceanic circulation, linkages with the biosphere, solid earth and sun, and finally reveals the relationship between earth's climate system and earth's surface system. The goal of Deep Time is to read, date and model earth's past climate system. To achieve this, development of a continental drilling program to enable acquisition and preservation of continuous, highresolution datasets is the most important. It is predictable that Deep Time together with Deep Space, Deep Sea and Deep Interior will be new fields in Geosciences. Sedimentology will play a core role in Deep Time research.
2009, 27(5): 818-825.
Abstract:
Numerous studies have been conducted in recent years on the Neoproterozoic South China palaeocontinents, and notable advances are generalized in the following aspects, including: (1) advances in the researches of the Neoproterozoic Nanhua rifting related to the evolution of the South China palaeocontinents, Chang’anian and Nantuoan glaciation and sedimentary events, and stratigraphic division and correlation of the Banxi Group, and (2) progress towards the researches of volcanicmagmatic events associated with the palaeocontinental evolution and concomitant studies of lithogeochemistry, isotope geochemistry and chronology. In view of the current status of research, the authors in this paper present a detailed review of the researches of Neoproterozoic South China palaeocontinents, especially the stratigraphic division and correlation of the wedgeshaped strata above the JinningSibao unconformity and the ages of the metamorphic rocks beneath the unconformity, the attributes of sedimentary basins, sedimentary evolution and tectonic settings. The authors have also been looking forward to greater progress in the studies of the abovementioned fields in the near future.
Numerous studies have been conducted in recent years on the Neoproterozoic South China palaeocontinents, and notable advances are generalized in the following aspects, including: (1) advances in the researches of the Neoproterozoic Nanhua rifting related to the evolution of the South China palaeocontinents, Chang’anian and Nantuoan glaciation and sedimentary events, and stratigraphic division and correlation of the Banxi Group, and (2) progress towards the researches of volcanicmagmatic events associated with the palaeocontinental evolution and concomitant studies of lithogeochemistry, isotope geochemistry and chronology. In view of the current status of research, the authors in this paper present a detailed review of the researches of Neoproterozoic South China palaeocontinents, especially the stratigraphic division and correlation of the wedgeshaped strata above the JinningSibao unconformity and the ages of the metamorphic rocks beneath the unconformity, the attributes of sedimentary basins, sedimentary evolution and tectonic settings. The authors have also been looking forward to greater progress in the studies of the abovementioned fields in the near future.
2009, 27(5): 837-848.
Abstract:
A systematic study on the physicalchemicalbiological processes of diagenesis has become an international academic hot spot. However, with the strengthening awareness about the importance of diagenesis in sedimentary basin, especially in fossil energy basin, it request more and more precise definition of the spatiotemporal attributes. In view of basin geodynamics evolution, this paper propose an ideas for spatiotemporal distribution research of diagenesis based on sedimentary sequence (rockmineralchemical system configuration), burial evolusion, structural strain pattern and fluid flow frameworks. We also discuss some key problems and research trend of diagenetic geodynamic mechanism and spatiotemporal distribution, such as the effect of surface temperature change on burial diagenesis, later diagenetic modification controlled by sedimentary lithofacies and their mineralchemical system, fault facies, deformation bands and their influences on cracks or strong compaction of clastic reservoir, coupling mechanism between structure strain and fluid flow and the fluidrock interaction effects, etc.
A systematic study on the physicalchemicalbiological processes of diagenesis has become an international academic hot spot. However, with the strengthening awareness about the importance of diagenesis in sedimentary basin, especially in fossil energy basin, it request more and more precise definition of the spatiotemporal attributes. In view of basin geodynamics evolution, this paper propose an ideas for spatiotemporal distribution research of diagenesis based on sedimentary sequence (rockmineralchemical system configuration), burial evolusion, structural strain pattern and fluid flow frameworks. We also discuss some key problems and research trend of diagenetic geodynamic mechanism and spatiotemporal distribution, such as the effect of surface temperature change on burial diagenesis, later diagenetic modification controlled by sedimentary lithofacies and their mineralchemical system, fault facies, deformation bands and their influences on cracks or strong compaction of clastic reservoir, coupling mechanism between structure strain and fluid flow and the fluidrock interaction effects, etc.
2009, 27(5): 863-871.
Abstract:
Basin fluid flow will change a diagenetic condition including temperature, pressure and fluid geochemistry in a pore space of host rocks, and result in the variation of sequential diagenetic processes, interaction of water and rock, and porosity of reservoir. Viewing in siliciclastic rocks, fluid flow only results in dissolution of minor mineral and modification of pore space due to mineral dissolution and precipitation. Fluid with plentiful of CO2 and organic acid will provide an available condition for the development of secondary porosity. Fluid episodic expulsion in overpressured environment not only results in the formation of secondary porosity in the overpressured compartment, but also results in the occurrence of abnormally diagenesis due to perturbations in temperature in shallow reservoirs with a hydrostatic environment. Viewing in carbonate rocks, because of strong dissolution of carbonate rocks, basin fluid flow can result in an essential variation in fabric and pore space in carbonate reservoirs. Expulsion of metroric inleakage and deep volcanic or hydrothermal fluids along faults or fractures will result in an essential variation in composition, texture, reservoir space in a vast realm in carbonate rocks. Hence, weathering karst typed and structurally controlled hydrothermal dolomitization typed reservoirs related closely to basin fluid movement are taken as main reservoir in carbonate rocks. However, basin fluid flow and associated diagenetic process has remained a matter of controversy, much more research are needed in the future.
Basin fluid flow will change a diagenetic condition including temperature, pressure and fluid geochemistry in a pore space of host rocks, and result in the variation of sequential diagenetic processes, interaction of water and rock, and porosity of reservoir. Viewing in siliciclastic rocks, fluid flow only results in dissolution of minor mineral and modification of pore space due to mineral dissolution and precipitation. Fluid with plentiful of CO2 and organic acid will provide an available condition for the development of secondary porosity. Fluid episodic expulsion in overpressured environment not only results in the formation of secondary porosity in the overpressured compartment, but also results in the occurrence of abnormally diagenesis due to perturbations in temperature in shallow reservoirs with a hydrostatic environment. Viewing in carbonate rocks, because of strong dissolution of carbonate rocks, basin fluid flow can result in an essential variation in fabric and pore space in carbonate reservoirs. Expulsion of metroric inleakage and deep volcanic or hydrothermal fluids along faults or fractures will result in an essential variation in composition, texture, reservoir space in a vast realm in carbonate rocks. Hence, weathering karst typed and structurally controlled hydrothermal dolomitization typed reservoirs related closely to basin fluid movement are taken as main reservoir in carbonate rocks. However, basin fluid flow and associated diagenetic process has remained a matter of controversy, much more research are needed in the future.
2009, 27(5): 880-895.
Abstract:
With the petroleum exploration and development of many oilproducing countries or areas in the world becoming increasingly mature, the problem of reservoir geology has become one of the main bottleneck problems of restricting petroleum exploration and development in petroleum industry. In order to improve exploration success ratio and development EOR and to further realize the purpose of “increasing reserves and production”, to carry out comprehensively the precise prediction for the spatial distribution of multiparameter of a sedimentary reservoir and the research on characterization methods and technologies have become the indispensable content in the current work of petroleum geology. The principally important is that they all can't depart from the kernel foundation of reservoir sedimentology. Started from 1960s, reservoir sedimentology has a development course of over 40 years. Based on the summery of the research progress both in China and abroad, this paper mainly has applied a view of historical materialism to expatiate the formation background of this subject, the demands of petroleum industry, the interpenetration of multidiscipline, the formation and development trend of this subject's specialization and research approaches. Meanwhile, current some research hot points of clastic reservoir sedimentology have been summarized and discussed, such as research methods of modern sedimentation and outcrop, application of geophysical method, the mapping method of sedimentary facies by multiparameter, application of sequence stratigraphy, the genesis of sedimentary reservoir in deep water, the formation and application of seismic sedimentology, depositional filling models of nonmarine basin, and reservoir diagenesis, etc. And then, some suggestions have been put forward on important problems to deepen the research on this subject.
With the petroleum exploration and development of many oilproducing countries or areas in the world becoming increasingly mature, the problem of reservoir geology has become one of the main bottleneck problems of restricting petroleum exploration and development in petroleum industry. In order to improve exploration success ratio and development EOR and to further realize the purpose of “increasing reserves and production”, to carry out comprehensively the precise prediction for the spatial distribution of multiparameter of a sedimentary reservoir and the research on characterization methods and technologies have become the indispensable content in the current work of petroleum geology. The principally important is that they all can't depart from the kernel foundation of reservoir sedimentology. Started from 1960s, reservoir sedimentology has a development course of over 40 years. Based on the summery of the research progress both in China and abroad, this paper mainly has applied a view of historical materialism to expatiate the formation background of this subject, the demands of petroleum industry, the interpenetration of multidiscipline, the formation and development trend of this subject's specialization and research approaches. Meanwhile, current some research hot points of clastic reservoir sedimentology have been summarized and discussed, such as research methods of modern sedimentation and outcrop, application of geophysical method, the mapping method of sedimentary facies by multiparameter, application of sequence stratigraphy, the genesis of sedimentary reservoir in deep water, the formation and application of seismic sedimentology, depositional filling models of nonmarine basin, and reservoir diagenesis, etc. And then, some suggestions have been put forward on important problems to deepen the research on this subject.
2009, 27(5): 904-914.
Abstract:
Sequence stratigraphy provides a new clue for the coal geologists to understand coal accumulation mechanism. After two decades studies in coal measures sequence stratigraphy, coal geologists realize that cyclicity in coal measures is closely related to the global sea level changes, and that industrial coals in geological history were mainly accumulated during a baselevel (sea level) rise. New coal accumulation models based on sequence stratigraphy theory were put forward by Chinese coal geologists, including episodic coal accumulation, transgressive process coal accumulation, event coal accumulation, and coal accumulation during a lag time of marine limestone beds. In the mean time, distribution model of thick coal seams in a sequence stratigraphic framework is outlined based on the balance between the peat accumulation rate and the accommodation creation rate. Future studies of coal measures sequence stratigraphy will focus on the sequence stratigraphic pattern of different tectonic coal basins, prediction of highquality coal distribution with sequence stratigraphy model, and the significance and implications of coals in the longterm evolution of Earth. Chinese coal geologists will put more efforts on the sequence stratigraphic pattern and coal accumulating model for the five coal accumulating provinces and will use sequence stratigraphy theory to find more highquality coal resources.
Sequence stratigraphy provides a new clue for the coal geologists to understand coal accumulation mechanism. After two decades studies in coal measures sequence stratigraphy, coal geologists realize that cyclicity in coal measures is closely related to the global sea level changes, and that industrial coals in geological history were mainly accumulated during a baselevel (sea level) rise. New coal accumulation models based on sequence stratigraphy theory were put forward by Chinese coal geologists, including episodic coal accumulation, transgressive process coal accumulation, event coal accumulation, and coal accumulation during a lag time of marine limestone beds. In the mean time, distribution model of thick coal seams in a sequence stratigraphic framework is outlined based on the balance between the peat accumulation rate and the accommodation creation rate. Future studies of coal measures sequence stratigraphy will focus on the sequence stratigraphic pattern of different tectonic coal basins, prediction of highquality coal distribution with sequence stratigraphy model, and the significance and implications of coals in the longterm evolution of Earth. Chinese coal geologists will put more efforts on the sequence stratigraphic pattern and coal accumulating model for the five coal accumulating provinces and will use sequence stratigraphy theory to find more highquality coal resources.
2009, 27(5): 922-930.
Abstract:
Detrital material of terrigenous origin is the main deepwater geological research aim and it is very important to the world research program of “from source to sink”. Submarine canyonchannel system mass transport deposition (submarine slide) the main transportation and deposition system of the continental slope. Based on the studies of 2D multichannel seismic data, 3D multichannel seismic data, multibeam depth measurement data, side sonar data, gravity and piston coring data, we find that the large scale block body transportation system and deepwater channel system widely develop in the northern South China Sea. The examples of Baiyun sag and Qiongdongnan Basin reveal the planform, internal structure and deformation process of representative block body transportation, and further discover the formation and evolution processes of block body transportation. Using 2D/3D seismic data and various new numerical model methods, deepwater high sinuosity channels of Quaternary and its depositional facies characteristics, Pliocene central channel in Qiongdongnan Basin and the paleopearl river deepwater channels of Miocene are discovered. Deepwater depositional system is very important for the study of formation mechanism and distribution of hydrocarbon, as well as predication and protection of geohazards of deepwater projects.
Detrital material of terrigenous origin is the main deepwater geological research aim and it is very important to the world research program of “from source to sink”. Submarine canyonchannel system mass transport deposition (submarine slide) the main transportation and deposition system of the continental slope. Based on the studies of 2D multichannel seismic data, 3D multichannel seismic data, multibeam depth measurement data, side sonar data, gravity and piston coring data, we find that the large scale block body transportation system and deepwater channel system widely develop in the northern South China Sea. The examples of Baiyun sag and Qiongdongnan Basin reveal the planform, internal structure and deformation process of representative block body transportation, and further discover the formation and evolution processes of block body transportation. Using 2D/3D seismic data and various new numerical model methods, deepwater high sinuosity channels of Quaternary and its depositional facies characteristics, Pliocene central channel in Qiongdongnan Basin and the paleopearl river deepwater channels of Miocene are discovered. Deepwater depositional system is very important for the study of formation mechanism and distribution of hydrocarbon, as well as predication and protection of geohazards of deepwater projects.
2009, 27(5): 939-955.
Abstract:
Based on sedimentary facies observation of many wells cores and outcrops, seismic sequence interpretation and seismic facies analysis, synthesizing the regional geological data such as ophiolitemelange and plate tectonic evolution, it's first worked out the 8 lithofacies paleogeography maps of Ordovician in Tarim basin under the sequence stratigraphy framework (Fig.1, Fig.2, Fig.9 to Fig.12, Fig.16 and Fig.17), and found the 5 isolated carbonate platforms (Northern Tarim Platform, BaChuCentral Tarim Platform, Western LuoBuBo Platform, Southern Tarim Platform, KuLuKeTaGe Platform) of Ordovician in Tarim plate and the basins between them, it's very important to marine oil & gas exploration in Tarim basin. The continental riftogenesis initially developed at the northern margin of Tarim plate in Cryogenian and Early Cambrian, and the tensional stress tectonic environment from Late Neoproterozoic to Middle Ordovician, controlled the formation of several isolated carbonate platforms and the deep water sedimentation areas between them in Tarim plate, otherwise, the collision compressional movement developed between A'ErJin arc, KuDi arc and Tarim plate at the south margin of Tarim in Late Ordovician and abundance terrigenous clasts produced by the collision, brought on gradually disappear of isolated carbonate platforms and the formation of turbidite sedimentary basins distributed in the southern Tarim.
Based on sedimentary facies observation of many wells cores and outcrops, seismic sequence interpretation and seismic facies analysis, synthesizing the regional geological data such as ophiolitemelange and plate tectonic evolution, it's first worked out the 8 lithofacies paleogeography maps of Ordovician in Tarim basin under the sequence stratigraphy framework (Fig.1, Fig.2, Fig.9 to Fig.12, Fig.16 and Fig.17), and found the 5 isolated carbonate platforms (Northern Tarim Platform, BaChuCentral Tarim Platform, Western LuoBuBo Platform, Southern Tarim Platform, KuLuKeTaGe Platform) of Ordovician in Tarim plate and the basins between them, it's very important to marine oil & gas exploration in Tarim basin. The continental riftogenesis initially developed at the northern margin of Tarim plate in Cryogenian and Early Cambrian, and the tensional stress tectonic environment from Late Neoproterozoic to Middle Ordovician, controlled the formation of several isolated carbonate platforms and the deep water sedimentation areas between them in Tarim plate, otherwise, the collision compressional movement developed between A'ErJin arc, KuDi arc and Tarim plate at the south margin of Tarim in Late Ordovician and abundance terrigenous clasts produced by the collision, brought on gradually disappear of isolated carbonate platforms and the formation of turbidite sedimentary basins distributed in the southern Tarim.
2009, 27(5): 967-975.
Abstract:
For a long time, the evolution relationships between Luxi uplift and peripheral basins during Cenozoic is a research hotspot.In this study, Boxing Sag has been selected as the target area, and the evolution history between Luxi uplift and peripheral basins has been discussed on the basis of the analysis from the exact high spatial resolution for the detrital garnets from Cenozoic various horizons, and the exclusiveness of garnets compositions and their content variation. The results show that the primary provenance of Boxing Sag were from the Luxi uplift and Jiaodong terrane during Cenozoic, more importantly Jiaodong terrane. The content variation of detrital garnet implies that Luxi uplift had been rising up quickly during early Neogene, and two smallscale uplifts has been conjectured from Paleocene to early Eocene and from late Eocene to early Oligocene respectively.
For a long time, the evolution relationships between Luxi uplift and peripheral basins during Cenozoic is a research hotspot.In this study, Boxing Sag has been selected as the target area, and the evolution history between Luxi uplift and peripheral basins has been discussed on the basis of the analysis from the exact high spatial resolution for the detrital garnets from Cenozoic various horizons, and the exclusiveness of garnets compositions and their content variation. The results show that the primary provenance of Boxing Sag were from the Luxi uplift and Jiaodong terrane during Cenozoic, more importantly Jiaodong terrane. The content variation of detrital garnet implies that Luxi uplift had been rising up quickly during early Neogene, and two smallscale uplifts has been conjectured from Paleocene to early Eocene and from late Eocene to early Oligocene respectively.
2009, 27(5): 983-994.
Abstract:
Along with the continuously proceeding of petroleum exploration in the Lower Palaeozoic carbonate in Tazhong area, a series of hydrothermal minerals such as fluorite, sphalerite, schatzite, baritite, anhydrite, pyrobitumen, and hydrothermal quartz and their associations are found in the Ordovician reservoir in outcrops and the relative exploration wells of Tazhong area repectively, More and more geological data show that the hydrothermal karst reservoir may be an important type neglected in the Lower Palaeozoic carbonate petroleum exploration in Tarim Basin.By the observation and measurements of outcrop hydrothermal karst phenomena in the recent six years, large amount of thin sections observation, mineral energy spectrum detecting, formation water strontium isotopes analysis, and study about faults nature of the Ordovician reservoir in well field of Tazhong 82 and 24,The active characteristics of the hydrothermal corrosion fluid and its controlling factor on the formation of quality reservoir are in deep study, The hydrothermal karst reservoir geological model is established finally. The results show that the hydrothermal minerals are mainly developed in the associating structural dissolution fractures along faults, corrosional vugs and the faults,they are the main pathway for hydrothermal fluid migration and the important factors controlling the formation of quality reservoir. The hydrothermal corrosion altering reservoir are widely developed in the Ordovican reservoir in the proximity of the strike faults formed in Hercynian in Tazhong area, which can be the petroleum exploration targets of the Upper Ordovician strata along the strike faults in the western part of Tazhong.
Along with the continuously proceeding of petroleum exploration in the Lower Palaeozoic carbonate in Tazhong area, a series of hydrothermal minerals such as fluorite, sphalerite, schatzite, baritite, anhydrite, pyrobitumen, and hydrothermal quartz and their associations are found in the Ordovician reservoir in outcrops and the relative exploration wells of Tazhong area repectively, More and more geological data show that the hydrothermal karst reservoir may be an important type neglected in the Lower Palaeozoic carbonate petroleum exploration in Tarim Basin.By the observation and measurements of outcrop hydrothermal karst phenomena in the recent six years, large amount of thin sections observation, mineral energy spectrum detecting, formation water strontium isotopes analysis, and study about faults nature of the Ordovician reservoir in well field of Tazhong 82 and 24,The active characteristics of the hydrothermal corrosion fluid and its controlling factor on the formation of quality reservoir are in deep study, The hydrothermal karst reservoir geological model is established finally. The results show that the hydrothermal minerals are mainly developed in the associating structural dissolution fractures along faults, corrosional vugs and the faults,they are the main pathway for hydrothermal fluid migration and the important factors controlling the formation of quality reservoir. The hydrothermal corrosion altering reservoir are widely developed in the Ordovican reservoir in the proximity of the strike faults formed in Hercynian in Tazhong area, which can be the petroleum exploration targets of the Upper Ordovician strata along the strike faults in the western part of Tazhong.
2009, 27(5): 1001-1011.
Abstract:
By analysing abundant crop and core data, Lianglitage Formation of Upper Ordovician in the northern margin of isolated platform has been identified five microfaces which are bank, bafflereef, algae mat, subtidal low energy zone. According to the highlow order of depositional energy, it constructs high frequency sedimentary group(reefbank,reefbandmound,bankmound, grainstone bank,bankalgae mat,moundalgae mat, algae mat,low energy zonealgae mat) and analyses this eight depositional group evolution rule under the sequence framework.On this basis, synthesizing seismic data and research result of predecessors, it is divided into four aggradating rimmedshelf sedimentary models delicately:1)faultcontrolling narrow and sharp rimmed platform,taking Tazhong 261 area for example; 2)faultcontrolling wide and sharp rimmed platform,taking Tazhong 621 area for example; 3)depositing wide and sharp rimmed platform,taking Tazhong 82 area for example; 4)depositing wide and gentle rimmed platform,taking Tazhong 452 area for example. Faultcontrolling platform margin has high energy, which is beneficial for reefbeach complex growth.These established models provide a valuable reference for Lianglitage Formation's exploration.
By analysing abundant crop and core data, Lianglitage Formation of Upper Ordovician in the northern margin of isolated platform has been identified five microfaces which are bank, bafflereef, algae mat, subtidal low energy zone. According to the highlow order of depositional energy, it constructs high frequency sedimentary group(reefbank,reefbandmound,bankmound, grainstone bank,bankalgae mat,moundalgae mat, algae mat,low energy zonealgae mat) and analyses this eight depositional group evolution rule under the sequence framework.On this basis, synthesizing seismic data and research result of predecessors, it is divided into four aggradating rimmedshelf sedimentary models delicately:1)faultcontrolling narrow and sharp rimmed platform,taking Tazhong 261 area for example; 2)faultcontrolling wide and sharp rimmed platform,taking Tazhong 621 area for example; 3)depositing wide and sharp rimmed platform,taking Tazhong 82 area for example; 4)depositing wide and gentle rimmed platform,taking Tazhong 452 area for example. Faultcontrolling platform margin has high energy, which is beneficial for reefbeach complex growth.These established models provide a valuable reference for Lianglitage Formation's exploration.
2009, 27(5): 1018-1026.
Abstract:
It is demonstrated by a series of measured data on chemical elements, rare elements and REE elements of the Shisanlitai Formation as follows: Fe2O3/FeO near or more than 2, δEu less than 1, despite one sample of Ceanom less than 0, U/Th ratio less than 0. 75, V/Cr less than 2, Ni/Co less than 5, all of those reflect a high oxidation environment, which is caused by shallow water body of the Shisanlitai Formation. A rich K, SiO2 and REE special mudstone of the Shisanlitai Formation offered plenty of materials for the formation of authegenic monazite. The mudstone contains low CaO less than 0.68%, CaO/MgO less than 0.6, Sr/Ba less than 0.33, which reflect low salinity during diagenetic stage, might be a fresh water lagoon back stromatolite reef environment. The tectonic environment might be a stable stage after Rodinia supper continent crack stage in the Shisanlitai Formation stage.
It is demonstrated by a series of measured data on chemical elements, rare elements and REE elements of the Shisanlitai Formation as follows: Fe2O3/FeO near or more than 2, δEu less than 1, despite one sample of Ceanom less than 0, U/Th ratio less than 0. 75, V/Cr less than 2, Ni/Co less than 5, all of those reflect a high oxidation environment, which is caused by shallow water body of the Shisanlitai Formation. A rich K, SiO2 and REE special mudstone of the Shisanlitai Formation offered plenty of materials for the formation of authegenic monazite. The mudstone contains low CaO less than 0.68%, CaO/MgO less than 0.6, Sr/Ba less than 0.33, which reflect low salinity during diagenetic stage, might be a fresh water lagoon back stromatolite reef environment. The tectonic environment might be a stable stage after Rodinia supper continent crack stage in the Shisanlitai Formation stage.
