摘要:
鄂西二叠纪的有孔虫类极为丰富，几乎产于各类碳酸盐岩中。其系统演化快，地理分布广，因此对其生态环境的研究，对于恢复古海域各种沉积环境，具有较大的意义。我国对二叠纪有孔虫的研究多则重于分类学和各地层单位中有孔虫组合特征及其地层学意义方面，而对有孔虫生态还很少有系统的研究。傅瑜(1979)应用有孔虫和藻类分布特征探讨四川盆地阳新世沉积条件就是一种尝试。笔者拟从碳酸盐岩岩石学、岩相古地理学、化石岩石学等方面入手，通过对碳酸盐岩微相环境的分析，与碳酸盐岩中的有孔虫组合特征及其形态结合起来，探讨二叠纪有孔虫的生态环境。 鄂西二叠纪的有孔虫类极为丰富,几乎产于各类碳酸盐岩中。其系统演化快,地理分布广,因此对其生态环境的研究,对于恢复古海域各种沉积环境,具有较大的意义。我国对二叠纪有孔虫的研究多则重于分类学和各地层单位中有孔虫组合特征及其地层学意义方面,而对有孔虫生态还很少有系统的研究。傅瑜(1979)应用有孔虫和藻类分布特征探讨四川盆地阳新世沉积条件就是一种尝试。笔者拟从碳酸盐岩岩石学、岩相
Abstract:
The Permian carbonate rocks are widespread in western Hubei.Apart from some clastic rocks at the bottom of Qixia Formation or at the top of Maokou Formation.most of them are carbonate deposits in ichich abundant foraminifears can be found。According to the origin一textural types carbonate rocks.indee of cater energy,and other biological assemblages associated with benthos foraminifera.the carbonate rocks can be subdivided into the folloivind 6 types of fades as well as 10 types of microfacies(Fig. I):a.Deep shelf It includes 3 types of microfacies(Plate 1,2).This facies is rich in argillo-calcareous composition and small bioclasts kith pelagic fauna,e.g.ammonite,sponge-spiculite.Algae are scarce.Among foraminifersa.the type of deep vrater such as iguiella.Palaeofusulina. Codonofusiella(P2),and Schwagerina,Chusenlla,Rugos-oschwagerina(P21),are predominant.b.Near shore shelf It contains 3 types of microfacics(Plate. 3).Sedimentary property and fossil assemblage show a lowtide open sea area near shore. There appear abundant green algae(Dasycladaceae).Adaptable fusulina such as Nankinella, Pisolina,Splraeru-lina and Verbeekina, as well as non-fusuline foraminiferas such as Pachyphloia,Padangia, Cribrogenerina, Climaeammia and so on.c.Tide shoal The type of rock is pelsparite(Plate 4,5)with red algae and green algae.This facies is formed in a lowtide high-energy and shallow water belt with normal salinity Fusulina specially thrive on,such as Yabeina Neosrhwagerina, Colania,Sumatrina, Pseudoliolina,Yerbeekinaand so on.Non-fusuline foraminiferas,Pachy-phloia,Cribrogerrerirra. Clinracammina and Nodosario are the most.d.Algal mud mound Algal limestone and micrite algal limestone are common types of carbonate rocks(Plate 7).Red algal Gymnorodiareae is well developed,while foraminifera has seldom grown to a thrifty colony·in whick a few of.Nankinella of Staffellidae are representative in early Lower Permian,and the genus of Srhwagerina arc abun-dant in Late Permian.Codonojusiella flourish in the Upper Permian.e.Intertidal flat The phyloid algal limestone is a representative of this facie (Plate 6).Nankin-ella is an adaptable fusulina to ecologic environment and becomes more prevalent.Non-fusuline foraminiferas including Eolasiodiscus, Glomospira and Nodosaria are the most abundant,the nest is Padangia. f.Restricted lagoon The rock type is silty micrite(Plate,8).The fossils consist of fragmental and scattered ostracodes,brachiopodas,bryozoans as well as Tubiphyfes,Vermiporella and Osagia. The species of non-fusulina or fusulina is simple,in which Padangia Perforata Lange are specially abundant. Only few Nankinella can be formed,which belongs to fusulina.The ecologic environment of foraminiferas is interpreted bt- means of studying on Permian carbonate microfacies and analysing their own architecture and morphologic function in this area.It is suggested that the foraminifera of Permian has not only obvious succession on vertical section,but is sensitive to living environment as well.There appear different units of foraminifera to various environments.
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