标题：An ice sheet advancing sequence at the beginning of the Cryogenian Sturtian glaciation

入藏号：WOS:001045910600001

中国科学院文献情报中心期刊分区：地球科学1区TOP（2023）

本校作者：郎咸国

来源出版物：GLOBAL AND PLANETARY CHANGE  卷: 227  文献号: 104185 

出版年：2023

第一地址： 成都理工大学

关键词：Facies analysis;The Gongdong Formation;The Chang'an Formation;Cryogenian;Neoproterozoic

代表图：

摘要：The global synchronous occurrence of glacial diamictite at the boundary of the Tonian-Cryogenian suggests a rapid onset of the Neoproterozoic Sturtian glaciation. However, uncomfortable contacts between the Tonian and Cryogenian successions obscure our understanding of ice sheet dynamics during the initiation of the global glaciation. Here, we perform a detailed facies analysis of two successions (the Tonian Gongdong to the Cryogenian Chang'an Formation) from the deep water facies of the Nanhua Basin, South China. Seven main lithofacies were recognized, including massive to laminated siltstone/muddy siltstone (Fm), ripple cross-laminated siltstone (Fr), massive to horizontal sandstone (Sm), gravely sandstone (Sg), matrix-supported massive diamictite (Dmm), weakly stratified diamictite (Dms) and dropstone bearing siltstone (Fdl). These facies were deposited from turbidity currents to glacial-influenced debris flows in deepwater environments. The top of the Gongdong Formation is mainly composed of massive to laminated siltstone/muddy siltstone and thin-bedded massive sandstone. The base of the Chang'an Formation is primarily constituted by massive to stratified diamictite. The gradual transition from massive to laminated siltstone to dropstone bearing siltstone and massive diamictite at the boundary between Gongdong and Chang'an formations indicates an ice sheet advancing sequence. The presence of abundant ice-rafted dropstones and rippled siltstone at the basal Chang'an Formation suggests active glacier calving and subglacial debris flows during ice sheet advancing. Also, the advancing ice sheet and glacial-influenced deposition are also supported by frequent changes in organic carbon isotope values (ranging from −26.5‰ to −29.3‰) that result from increasing terrestrial inputs. The ice sheet advancing sequence here shows that the global glaciation started within 1 million years, according to the average sedimentation rate of the glacial turbidity deposits. These findings provide the initial comprehensive sedimentological evidence for the rapid onset of Snowball Earth.

文章链接地址: https://www.sciencedirect.com/science/article/pii/S0921818123001583?via%3Dihub