成都理工大学学报（自然科学版）2025，Vol.52Issue(3)：379-393,15.DOI:10.12474/cdlgzrkx.2024122301
华南埃迪卡拉系蓝田组黄铁矿原位微量元素分布特征与古海洋环境指示
In situ trace element distribution characteristics of pyrite and their implications for paleoceanic environments in the Ediacaran Lantian Formation,South China
摘要
Abstract
Lying between the termination of the Neoproterozoic global glaciation and the onset of Cambrian explosion,the Ediacaran(635～541 Ma)represents a key transitional period in Earth's history which witnessed the emergence and diversification of metazoans in the late Neoproterozoic.Investigating the evolution of the paleoceanic environment during the Ediacaran is crucial to understand its impact on the evolution of early multicellular organisms.Trace element contents in sedimentary rocks are crucial for reconstructing paleoceanic environments.However,trace element enrichment in sediments is often influenced by factors such as the redox conditions of the overlying water column.In contrast,trace element contents in sedimentary pyrite can effectively avoid the influence of late diagenesis;e.g.,recrystallization,making it a promising indicator to reconstruct the redox states of paleooceans.Regardless,the diverse morphologies and complex origins of pyrite in sedimentary strata result in the complexity of its trace element composition.This study focuses on fresh deep-water core samples from the Lantian Formation in southern Anhui.By combining scanning electron microscopy with nanoscale secondary ion mass spectrometry,the morphology of pyrite and in situ trace element distributions are examined.These findings are further integrated with previously published in situ sulfur isotope data(δ34Spy)to elucidate the formation processes and environmental implications of pyrite.The results indicate that the dominant pyrite morphologies in the Lantian Formation are framboidal pyrite and euhedral/subhedral pyrite.Framboidal pyrite exhibits a higher average S/Fe atomic ratio compared to euhedral/subhedral pyrite,reflecting a sulfur-enriched formation environment.Trace element analysis reveal distinct correlations with δ34Spy values.The concentrations of As and Cu in framboidal pyrite show a negative correlation with δ34Spy,whereas those of euhedral and subhedral pyrite display a weak positive correlation with δ34Spy.These variations in the trace element distributions correspond to differences in pyrite formation environments.The reduced As and Cu contents in framboidal pyrite may be attributed to increased crystallinity of this type of pyrite,while the elevated As and Cu contents in euhedral/subhedral pyrite are likely associated with arsenic-driven cryptic sulfur cycling and the adsorption of these elements onto organic matter and detrital fraction during pyrite formation.This study shows that using trace element contents of pyrite to reconstruct paleoenvironmental redox conditions,fresh,unaltered framboidal pyrite may provide a more faithful record of the seawater redox conditions.关键词
扬子地台/埃迪卡拉系/蓝田组/黄铁矿形态/黄铁矿微量元素Key words
Yangtze Platform/Ediacaran/Lantian Formation/pyrite morphology/trace element in pyrite分类
天文与地球科学引用本文复制引用
胡永亮,赵显烨,王伟,郝佳龙,关成国,周传明..华南埃迪卡拉系蓝田组黄铁矿原位微量元素分布特征与古海洋环境指示[J].成都理工大学学报（自然科学版）,2025,52(3):379-393,15.基金项目
国家自然科学基金项目(42072036,41921002,42130207,42192501,2021YJCQ03). （42072036,41921002,42130207,42192501,2021YJCQ03）
