Characteristics, Genesis, and Sedimentary Environment of Duplex-Like Structures in the Jurassic Sedi

来源 :Journal of Earth Science | 被引量 : 0次 | 上传用户:golf
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
A particular type of soft-sediment deformation structure, similar to imbricate structure, is developed in the Jurassic strata at Honggouzi, western Qaidam Basin, China. We refer to this structure as a duplex-like deformation structure, because it is inferred to have been formed by the action of fast-moving, submarine gravity current sediments gliding across a pre-existing semiconsolidated sedimentary layer. The layers of duplex-like structure crop out in the southeastern limb of the core of a medium-sized anticline. The average dip direction of the duplex-like structure is 301.2° and the average dip angle is 54.7°. Duplex-like deformed laminations are composed mainly of weakly metamorphosed, extremely poorly sorted, feldspathic lithic graywacke. Sericite can be observed along bedding planes. The duplex-like structure occurs within a sequence of river-channel fine conglomerate, interchannel carbonaceous mudstone(shale), shallow-water delta sand-shale, shallow-lake calcareous mudstone, olistostromes, and a turbidite. At the bottom of the sequence, we found brownish-red shallow-lake calcareous mudstone and carbonaceous mudstone and at the top olistostromes whose genesis is related to the slip and drag of a slumped body of submarine sediment. In combination with other symbiotic and associated structures, it is considered that the duplex-like structure was formed by the slumping and subsequent movement and traction of delta-front semiconsolidated sediments over the bottom sediments of a shore or shallow-lake sedimentary environment, probably triggered by an earthquake. The attitude of the duplex-like structure indicates that the direction of gliding was from NW301.2° toward SE121°, which is consistent with the current location of the Altun Mountains, indicating that the Altun Mountains existed in the Jurassic. The orogenesis of these mountains likely involved seismic activity, and an earthquake was the triggering factor in the formation of the duplex-like structure by causing the slumping/gliding of the olistostrome sediments. A particular type of soft-sediment deformation structure, similar to imbricate structure, is developed in the Jurassic strata at Honggouzi, western Qaidam Basin, China. We refer to this structure as a duplex-like deformation structure, because it is inferred to have been formed by the action of fast-moving, submarine gravity current sediments gliding across a pre-existing semiconsolidated sedimentary layer. The layers of duplex-like structure crop out in the southeastern limb of the core of a medium-sized anticline. The average dip direction of the duplex-like structure is 301.2 ° and the average dip angle is 54.7 °. Duplex-like deformed laminations are composed mainly of weakly metamorphosed, extremely poorly sorted, feldspathic lithic graywacke. structure occurs within a sequence of river-channel fine conglomerate, interchannel carbonaceous mudstone (shale), shallow-water delta sand-shale, shallow-lake calcareous mudstone, At the bottom of the sequence, we found brownish-red shallow-lake calcareous mudstone and carbonaceous mudstone and at the top olistostromes whose genesis is related to the slip and drag of a slumped body of submarine sediment. In combination with other symbiotic and associated structures, it is considered that the duplex-like structure was formed by the slumping and subsequent movement and traction of delta-front semiconsolidated sediments over the bottom sediments of a shore or shallow-lake sedimentary environment, probably triggered by an earthquake. The attitude of the duplex-like structure that that direction of gliding was from NW301.2 ° toward SE121 °, which is consistent with the current location of the Altun Mountains, indicating that the Altun Mountains existed in the Jurassic. The orogenesis of these mountains likely involved seismic activity, and an earthquake was the triggering factor in the formation of the duplex-like structure b y causing the slumping / gliding of the olistostrome sediments.
其他文献
为探究吕家坨井田地质构造格局,根据钻孔勘探资料,采用分形理论和趋势面分析方法,研究了井田7
期刊
为探究吕家坨井田地质构造格局,根据钻孔勘探资料,采用分形理论和趋势面分析方法,研究了井田7
The reaction-transport model is widely used to identify and quantify dissolved chemical species in sediment porewaters. In this paper, a modularized code framew
为探究吕家坨井田地质构造格局,根据钻孔勘探资料,采用分形理论和趋势面分析方法,研究了井田7
期刊
In addition to syenite ring dykes and multiple alkaline granite stocks, the sub-volcanic Houshihushan alkaline ring complex near Shanhaiguan, Qinhuangdao City,
为探究吕家坨井田地质构造格局,根据钻孔勘探资料,采用分形理论和趋势面分析方法,研究了井田7
期刊
儿子放学回家,对我说:“老师今天摸了我的头。”“被老师摸了一下有什么了不起?”我正赶着做饭,没工夫搭理他,“摸了就摸了呗。”儿子似乎有许多话要说,心有不甘地走进了自己
通过分析国际海底地名分委会(SCUFN)会议纪要,研究日本与俄罗斯帝王海山链(Emperor Seamount Chain)之争、日本与俄罗斯日本平顶海山群(Japanese Guyots)之争和日本与美国幸
为探究吕家坨井田地质构造格局,根据钻孔勘探资料,采用分形理论和趋势面分析方法,研究了井田7
期刊
The Neogene eolian deposits in the Xining Basin are valuable archive for studying the evolution of the Asian monsoon system and geomorphic processes of Northwes