广元上寺剖面下三叠统飞仙关组风暴岩：巨型季风体制下的极端气候事件?
- 收稿日期:
1900-01-01
- 修回日期:
1900-01-01
- 刊出日期:
2011-06-10
摘要: 早三叠世扬子地台位于特提斯东北缘，研究者根据大量地质证据和模拟实验证实该时期巨型季风强度最大，且控制了整个泛大陆和周边海域的气候循环。笔者于川西北广元上寺剖面下三叠统中发现一套保存完好的风暴岩，其发育于飞仙关组下部，风暴沉积特征明显，风暴侵蚀构造、风暴撕裂构造和层理构造发育；根据沉积构造、岩石性质等识别了Sa-Sb-Sc、Sb-Sd、Sa-Sc-Sd三种序列组合（Sa-滞留砾屑沉积，Sb-粒序层理，Sc-丘状交错层理，Sd-均质层理）。早三叠世研究区处于有利于保存风暴沉积的浅海环境，风暴岩的形成、发展与特征对古气候研究有重要意义。我们认为上寺地区（乃至扬子地区）的风暴沉积，可能是最强盛的季风循环影响的结果；而P/T界线生物大量灭绝后缺乏潜穴生物的背景使风暴岩得以保存。
Tempestite of Early Triassic Feixianguan Formation in Shangsi Section, Guanyuan: Are they extreme climatic event under megamonsoon system?
- Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059
- Received Date:
1900-01-01
- Rev Recd Date:
1900-01-01
- Publish Date:
2011-06-10
Abstract: Early Triassic Yangtze platform was located in the northeastern margin of Tethys. Based upon the large amount of geological evidence and simulation experiments, researchers confirmed that the Triassic climate system was megamonsoon that controlled the climate of whole Pangaea and surrounding sea. However abundant outcrops of Triassic strata in our country, whether contained some information implying monsoon climate? We found a set of wellpreserved tempestite in the Lower Triassic at Shangsi Section, Guangyuan city, northwest Sichuan, which developed in the lower part of the Feixianguan Formation. The sedimentary characteristics of Lower Triassic Tempestite was significant, including stormgenerated gravel, storm erosion structures, storm tear structures and bedding structures. Gravel was composed of micritic limestone, and might be divided into two types according to roundness. One contained brecciated, strip, axiolitic shape; the other presented flatgravel shape. Storm erosion structures included pocket and chrysanthemum shape formed by drainage and channel mode, erosion surface structure. Storm tear structures included messy mud gravel, torn sutureline breccia and truncated structure amongst lays. Bedding structures included hummocky cross bedding, graded bedding,blocky bedding ,homogeneous bedding and parallel bedding. According to sedimentary structures and lithology, three kinds of sequence of SaSbSc, SbSd, SaScSd(Sastranded gravel deposition, Sbgraded bedding, Schummocky crossstratification, Sdhomogeneous bedding) were recognized. The storm deposits occurred in the shallow sea and the formation, development and characteristics of the tempestites have important significance on paleoclimate research. We think that tempstite in Shangsi (and even whole UpperYangtze region) was controlled likely by the strong monsoon system (Megamonsoon) in Early Triassic, and the P/T boundary mass extinction event let tempestite be preserved below the setting that organism burrows were few.
曾德勇. 广元上寺剖面下三叠统飞仙关组风暴岩：巨型季风体制下的极端气候事件?[J]. 沉积学报, 2011, 29(3): 440-448.
| 引用本文: |
曾德勇. 广元上寺剖面下三叠统飞仙关组风暴岩：巨型季风体制下的极端气候事件?[J]. 沉积学报, 2011, 29(3): 440-448.
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ZENG Deyong. Tempestite of Early Triassic Feixianguan Formation in Shangsi Section, Guanyuan: Are they extreme climatic event under megamonsoon system?[J]. Acta Sedimentologica Sinica, 2011, 29(3): 440-448.
| Citation: |
ZENG Deyong. Tempestite of Early Triassic Feixianguan Formation in Shangsi Section, Guanyuan: Are they extreme climatic event under megamonsoon system?[J]. Acta Sedimentologica Sinica, 2011, 29(3): 440-448.
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