沉积与特提斯地质2025，Vol.45Issue(1)：69-89,21.DOI:10.19826/j.cnki.1009-3850.2024.06003
大巴山地区Marinoan冰川沉积序列及其古气候演化:来自岩石学及地球化学的证据
Sedimentary sequence and paleoclimate evolution of the Marinoan Glacier in the Daba Mountains:Evidence from petrology and geochemistry
摘要
Abstract
There has been a long-standing debate that whether the earth was a"hard snowball"or a"slush snowball"during the Neoproterozoic Marinoan Ice Age.The glacial sediments of the Nantuo Formation from the Liangqiao section of Chengkou,in the Dabashan area,are complete with extensive development,providing an ideal target for studying the Marinoan glacial sedimentary sequence.Geochemical evidence is of great significance for reconstructing the late Neoproterozoic paleoclimate.The petrological characteristics of the Nantuo Formation show that it is predominantly composed of gray-green and gray-purple pebbly siltstone in the Daba Mountain area.The geochemical characteristics of the moraine deposits reveal that the Nantuo Formation in this area underwent low chemical weathering and was in a cold and dry climate.Paleoclimatic indicators,such as the chemical index of alteration(CIA),chemical index of weathering(CIW),and plagioclase index of alteration(PIA),exhibit clear cyclic variations.The gray-purple pebbly siltstone gradually decreases upwards from a high value in the bottom,while the gray-green pebbly siltstone gradually increases from bottom to top starting from a low value,implying multiple cold and warm paleoclimatic fluctuations in the early Nantuo period.Regional correlations and sedimentary patterns of the Nantuo Formation in the Yangtze area indicate that the Nantuo glacial period can be further divided into an early gradual freezing period,a middle frozen period,and a late thawing period.The climatic changes mainly occurred during the early and late Nantuo periods,especially in the shallow-water sedimentary areas.Therefore,evidence from the glacial sedimentary sequence and paleoclimatic variation of the Nantuo Formation supports the hypothesis that the earth was a"slush snowball"at the end of the Neoproterozoic era.关键词
大巴山地区/Marinoan冰期/沉积地球化学/冰川沉积序列/古气候演化Key words
Dabashan area/Marinoan Ice Age/sedimentary geochemistry/glacial sedimentary sequence/paleoclimatic evolution分类
天文与地球科学引用本文复制引用
彭洲俊,李小刚,熊国庆,谢忠评,冯翔游,陈春竺,彭惠雪,林茂..大巴山地区Marinoan冰川沉积序列及其古气候演化:来自岩石学及地球化学的证据[J].沉积与特提斯地质,2025,45(1):69-89,21.基金项目
重庆市自然科学基金面上项目(CSTB2024NSCQ-MSX1176) （CSTB2024NSCQ-MSX1176）
重庆科技大学研究生科技创新训练计划项目(YKJCX2220101) （YKJCX2220101）
自然资源部沉积盆地与油气资源重点实验室开放基金(cdcgs2022006) （cdcgs2022006）
国家自然科学基金(U2344209) （U2344209）
四川省科技厅中央引导地方发展专项(2023ZYD0153) （2023ZYD0153）
