摘要
柴达木盆地北缘的欧龙布鲁克微板块发育了一套元古宙碎屑岩与碳酸盐岩地层,以往被称为全吉群,不整合覆于变质结晶基底之上,伏于寒武系之下.这套地层在全吉山、石灰沟及欧龙布鲁克山等地区的多个剖面出露良好,但在石灰沟、欧龙布鲁克地区均有不同程度的缺失,而全吉山地区保存的沉积序列相对最为完整.前人对于全吉群的划分、对比及其沉积时代长期存在不同认识.在《中国地层表(2014)》中,全吉群包括麻黄沟组至皱节山组,其中麻黄沟组、枯柏木组和石英梁组属南华系,而红藻山组、黑土坡组、红铁沟组和皱节山组属震旦系.近年来,生物地层学、同位素年代地层学方面的证据表明,红藻山组及其下伏地层沉积于古元古代晚期到中元古代早期(距今约17～16亿年),代表了该时期的一套裂谷盆地沉积物,而上覆黑土坡组、红铁沟组和皱节山组则沉积于新元古代中晚期(晚于距今7.5亿年).考虑到这两套地层之间存在着8～9亿年的沉积间断,本文支持将全吉群进行重新定义,厘定后的全吉群仅包含麻黄沟组、枯柏木组、石英梁组和红藻山组,上覆新元古代地层(黑土坡组、红铁沟组和皱节山组)则不做群一级别的划分.
Abstract
The Proterozoic strata developed in the Olongbuluke terrane,the northern Qaidam Basin,Northwest China are composed of siliciclastic and carbonate rocks that unconformably sit on the Paleoproterozoic metamorphic basement and unconformably underlie the Cambrian rocks.The Proterozoic strata crop out well in the Quanjishan,Shihuigou,and Olongbuluke areas,and are most complete in the Quanjishan section,with an increasingly missing of sediments eastwards.There have been different stratigraphic schemes for the subdivision and correlation of the Proterozoic successions,as well as different opinions about their depositional age in the Olongbuluke terrane.According to the Stratigraphic Chart of China(2014),the Quanji Group consists of the Mahuanggou,Kubaimu,Shiyingliang,Hongzaoshan,Heitupo,Hongtiegou,and Zhoujieshan formations;the Mahuanggou,Kubaimu,and Shiyingliang formations have been regarded as the Nanhua System(roughly equals to the Cryogenian System),whereas the Hongzaoshan,Heitupo,Hongtiegou,and Zhoujieshan formations have been assigned to the Sinian System(equals to the Ediacaran System).However,recent advances in biostratigraphy and radiometric geochronology indicate that the Hongzaoshan Formation and its underlying strata were deposited at～1.7-1.6 Ga,representing a set of rift basin sediments from late Paleoproterozoic to early Mesoproterozoic,whereas the overlying Heitupo,Hongtiegou,and Zhoujieshan formations may belong to middle to late Neoproterozoic.Considering that there is a sedimentary hiatus of 800-900 Myr between the Hongzaoshan and Heitupo formations,we propose that the Quanji Group shall be redefined to contain only the late Paleoproterozoic to early Mesoproterozoic Mahuanggou,Kubaimu,Shiyingliang,and Hongzaoshan formations,and the overlying Neoproterozoic strata,including the Heitupo,Hongtiegou,and Zhoujieshan formations,shall temporarily not be included in any group-level lithostratigraphic units.
基金项目
青藏科考研究国家专项(第二次)(2019QZKK0706)
国家自然科学基金(42272005)
国家自然科学基金(41921002)
国家重点研发计划(2022YFF0802700)
现代古生物学和地层学国家重点实验室项目(20201102)
现代古生物学和地层学国家重点实验室项目(213108)
中国科学院青年创新促进会项目(2021307)
中国博士后科学基金(2021M693243)
NETL
NSTL
维普
万方数据