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Integrated sedimentological, ichnological and sequence stratigraphical studies of the Koti Dhaman Formation (Tal Group), Nigali Dhar Syncline, Lesser Himalaya, India: paleoenvironmental, paleoecological, paleogeographic significance
Ichnos ( IF 0.8 ) Pub Date : 2019-04-13 , DOI: 10.1080/10420940.2019.1584560
Birendra P. Singh 1 , Om N. Bhargava 1 , Radek Mikuláš 2 , Scott Morrision 3 , Ramanpreet Kaur 1 , Garry Singla 1 , Naval Kishore 1 , Neeraj Kumar 1 , Rohit Kumar 1 , Sakshi Moudgil 1
Affiliation  

Abstract Integrated ichnology, sedimentology and sequence stratigraphy of the Lower Quartzite Member to the Arkosic Sandstone Member of the Koti Dhaman Formation (Cambrian Series 2, Stage 4), Tal Group, Nigali Dhar Syncline, Lesser Himalayan lithotectonic zone are presented. Trilobite traces of Gondwanan affinity i.e., Cruziana salomonis, Cruziana fasciculata, Rusophycus dispar and Rusophycus burjensis are recorded along with Arenicolites isp. and Skolithos isp. from the Lower Quartzite Member. A rich and diverse ichnoassemblage attributed to the Cruziana ichnofacies is described for the first time from the Arkosic Sandstone Member of the same formation. Seven ichnofossil assemblages, i.e., Cruziana-Rusophycus, Planolites-Palaeophycus, Cruziana problematica, Diplichnites, Cochlichnus anguineus, Bergaueria perata and Psammichnites gigas have been recognized in the Lower Quartzite to Arkosic Sandstone members of the Koti Dhaman Formation. Seven sedimentary facies i.e., sandstone–shale facies (FT1), cross-bedded (trough and planar) sandstone (FT2), bedded sandstone facies (FT3), shale facies (FT4), shale–sandstone facies (FT5), shale-rippled sandstone facies (FT6) and planar and trough cross-laminated sandstone (FT7) and four facies associations FA1-FA4 are identified in the Koti Dhaman Formation. The formation contains shallowing upward parasequences of a tidal flat complex. Overall, two major events are recognized: i) the break in sedimentation between the Lower Quartzite Member and the overlying Shale Member probably related to forced-regressive event and ii) the facies shift from FT6 to FT7 of the Arkosic Sandstone Member represents an erosive transgressive event; the surface is interpreted as wave ravinement surface, which also serves as a sequence boundary. Integrated ichnology, sedimentology and sequence stratigraphic studies indicate that the Lower Quartzite Member was deposited in a shallow subtidal sand sheet complex and tidal flat complex; the Shale Member was deposited in a mud flat setting of a tidal flat complex, and the Arkosic Sandstone Member in a mixed-flat (tidal flat complex) to sand sheet complex front and margin (subtidal sand sheet complex). Overall, the lower to middle part of the Koti Dhaman Formation represents a tide-dominated shallow subtidal–intertidal to mud-flat subenvironments of the tidal flat complex. A palaeogeographic reconstruction of lower Cambrian (516–514 Ma) is presented based on the distribution of trilobite traces from the Lesser Himalaya and the Bikaner–Nagaur area of Peninsular India (eastern Gondwana), Egypt, Jordan, Turkey (western Gondwana) and Canada (Avalonia).

中文翻译:

印度小喜马拉雅山 Nigali Dhar 向斜 Koti Dhaman 组(Tal 组)的沉积学、地质学和层序地层学综合研究:古环境、古生态、古地理意义

摘要 介绍了Koti Dhaman组(寒武系2、4期)、Tal群、Nigali Dhar向斜、小喜马拉雅岩构造带下石英岩段至长石质砂岩段的综合地层学、沉积学和层序地层学。Gondwanan 亲和力的三叶虫痕迹,即 Cruziana salomonis、Cruziana fasciculata、Rusophycus dispar 和 Rusophycus burjensis 与 Arenicolites isp 一起记录。和 Skolithos isp。来自下石英岩成员。首次从同一地层的 Arkosic 砂岩段描述了属于 Cruziana 地层相的丰富多样的地层组合。七种鱼化石组合,即 Cruziana-Rusophycus、Planolites-Palaeophycus、Cruziana Problema、Diplichnites、Cochlichnus anguineus、Bergaueria perata 和 Psammichnites gigas 已在 Koti Dhaman 组的下石英岩至长石质砂岩成员中得到确认。七种沉积相,即砂岩-页岩相(FT1)、交错(槽和平面)砂岩(FT2)、层状砂岩相(FT3)、页岩相(FT4)、页岩-砂岩相(FT5)、页岩波纹在 Koti Dhaman 组中确定了砂岩相 (FT6) 和平面和槽交叉层状砂岩 (FT7) 以及四个相组合 FA1-FA4。该地层包含潮滩复合体的向上变浅的准层序。总体而言,有两个重大事件得到认可:i) 下石英岩段和上覆页岩段之间的沉积中断可能与强迫海退事件有关; ii) 长石英砂岩段从 FT6 到 FT7 的相移代表了侵蚀性海侵事件;该表面被解释为波谷表面,它也作为层序边界。综合地层学、沉积学和层序地层学研究表明,下石英岩段沉积于浅层潮下砂岩复合体和潮坪复合体中;页岩段沉积在潮滩复合体的泥滩环境中,长石砂岩段沉积在混合滩(潮滩复合体)到砂板复合体的前缘和边缘(潮下砂板复合体)中。全面的,Koti Dhaman 组的中下部代表了潮滩复合体的一个以潮汐为主的浅潮间带至泥滩亚环境。根据来自小喜马拉雅山和印度半岛(冈瓦纳东部)、埃及、约旦、土耳其(冈瓦纳西部)和加拿大的比卡内尔-纳高尔地区的三叶虫痕迹分布,提出了下寒武统(516-514 Ma)的古地理重建(阿瓦隆尼亚)。
更新日期:2019-04-13
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