扬子西缘泥盆纪碳酸盐与陆源碎屑的混积层序和层序混积模式
- 收稿日期:
1998-05-12
- 修回日期:
1998-07-30
- 刊出日期:
1999-09-10
摘要: 扬子西缘龙门山山前带泥盆纪发育一套碳酸盐与陆源碎屑混合的沉积体系，这套混积沉积体系中可识别出2个层序组、8个混积层序。研究表明，SS2 层序组的各层序( S4 ～ S7)混积作用主要产生于TST中，SS3 层序组的各层序（ S8 ～ S11） 混积作用则集中于SMT/ LST及早期 TST, HST普遍不发育混积作用；从SS2 到 SS3，混积类型由泥质陆棚背景的混积Ⅰ型向砂灰质混积Ⅱ型转变，混积作用从间断和原地混合到相的混合变化；SS2各层序具有持续缓慢海侵—相对快速海退特点，总体表现出较长期的构造活跃—较短期稳定样式，SS3各层序则具相对快速海侵—持续缓慢海退结构，总体构造活跃样式为四个活跃—稳定叠加的跳跃式。
Sequence Stratigraphy of Mixed Carbonate and Siliciclastic Sediments in Devonian Along the Western Margin of Yangtze Plate
- Institute of Sedimentary Geology,Chengdu University of Technology,610059 Chengdu
- Received Date:
1998-05-12
- Rev Recd Date:
1998-07-30
- Publish Date:
1999-09-10
Abstract: There are well exposed carbonate and terrigenous mixtures in the Lower-Middle Devonian in the northwestern Yangtse Craton,China.On the bases of measuring sections,investigating boundary surfaces,and correlating decade sections,hybrid depositional sequences are recognized,and mixings in systems tracts and tectonic significance are analyzed in the paper. Eight hybrid depositional sequences can be distinguished from the top Pragian to the early Givetian in the study area.They are nominated S4,S5,S6,S7,S8,S9,S10,S11 separately which can be classified into two hybrid depositional sequence sets SS2 (S4-S7),and SS3 (S8-S11).Sedimentation in TSTs,Little SMTs and HSTs of depositional sequences in SS2,is characterized by in-situ mixing and punctuated mixing.And source mixings could be only completed in the early TSTs of S7 and S8,but the facies mixing is predominated in early TSTs of most depositional sequences in SS3 and in the HST of S9.It is proposed that mixing of carbonate and terrigenous sediments can be done in anyone of LST/SMT,TST,and HST.This is slightly different from the propositions,among which someone suggested that a mixing could have been only undertaken in HST or in LST. The changes of systems tracts thickness,and relationships between mixing and tectonic are also discussed in the paper.Each of the depositional sequences in SS2 is characterized by the pattern of TST≥HST+SMT except for the S7,and vice versa,any of depositional sequences in SS3 has a texture of HST≥TST+SMT/LST.A relatively active tectonic subsidence was transferred to a stable tectonism at the SMT of S7 in SS2,and a pattern of relatively active to stable tectonism in each of S8 S9,S10,S11 is induced in SS3.That is to say,the patterns of transgression to regression (T-R) could be a way of continuous and slow transgression to relatively fast regression in SS2,and be the tendency of relatively fast transgression to slow regression in each depositional sequence of SS3. We have three questions on the intervals between large-scale boundary surfaces.①If an extensively tectonic activity has ever done at the gap between the pure terrigenous sediments (Pingyipu Formation) and the mixed carbonate and siliciclastic sediments.②If an exposing event existed that is displayed by ooidal hematite between the SS2 and SS3.③If a sea-level falling event with a tectonic uplift took place at the transition of the hybrids to carbonate.
李祥辉, 曾允孚. 扬子西缘泥盆纪碳酸盐与陆源碎屑的混积层序和层序混积模式[J]. 沉积学报, 1999, 17(3): 339-344.
| 引用本文: |
李祥辉, 曾允孚. 扬子西缘泥盆纪碳酸盐与陆源碎屑的混积层序和层序混积模式[J]. 沉积学报, 1999, 17(3): 339-344.
|
LI Xiang hui, ZENG Yun fu. Sequence Stratigraphy of Mixed Carbonate and Siliciclastic Sediments in Devonian Along the Western Margin of Yangtze Plate[J]. Acta Sedimentologica Sinica, 1999, 17(3): 339-344.
| Citation: |
LI Xiang hui, ZENG Yun fu. Sequence Stratigraphy of Mixed Carbonate and Siliciclastic Sediments in Devonian Along the Western Margin of Yangtze Plate[J]. Acta Sedimentologica Sinica, 1999, 17(3): 339-344.
|
点击查看大图
下载:
