滇东会泽地区筇竹寺组黑色岩系古环境、物源及构造背景:来自稀土元素地球化学的指示  

Paleoenvironmental,provenance,and tectonic setting of the Qiongzhusi Formation black shale series in Huize area,eastern Yunnan:insights from rare earth element geochemistry

作　　者：程涌 文义明 聂琪 罗开 张金梁 和东浩 刘洋 伍伟 CHENG Yong;WEN Yiming;NIE Qi;LUO Kai;ZHANG Jinliang;HE Donghao;LIU Yang;WU Wei(Faculty of Metallurgy and Mining Engineering,Kunming Metallurgy College,Kunming,Yunnan 650033,China;School of Earth Sciences,Yunnan University,Kunming,Yunnan 650500,China)

机构地区：[1]昆明冶金高等专科学校冶金与矿业学院,云南昆明650033 [2]云南大学地球科学学院,云南昆明650500

出　　处：《矿物岩石》2024年第4期58-70,共13页Mineralogy and Petrology

基　　金：国家自然科学基金项目(批准号:41672073);云南省科技厅科技计划项目(编号:202401AT070047);昆明冶金高等专科学校基金(编号:2022xjy23)。

摘　　要：滇东地区早寒武世广泛发育的黑色岩系不仅是页岩气勘探的潜在层位,也具有显著的矿产勘探前景。本研究以会泽地区下寒武统筇竹寺组的黑色岩系为对象,通过系统的采样和稀土元素(REE)分析,旨在揭示其古环境、构造背景和物源,从而为矿床勘查和页岩气评价提供地质依据。分析结果显示,黑色岩系的稀土总量(ΣREE)含量介于26.11×10^(-6)~272.82×10^(-6)之间,表现出轻稀土元素富集、重稀土元素平坦的配分特征,伴随中度的负Eu异常和轻度的负Ce异常,与大陆上地壳稀土元素配分模式相似。样品的ΣREE从下部到上部总体有所增加,揭示了沉积期间总体较为温暖潮湿的气候特征。δCe值和Ce_(anom)值表明,筇竹寺组形成于沉积水体较深的贫氧环境。(Eu/Sm)_(N)-(Sm/Yb)_(N)二元图解及微量元素特征指示了该黑色岩系受到了富金属热水作用的轻微影响。通过综合分析δEu、δCe、ΣREE及其他地球化学参数,推断筇竹寺组黑色岩系母岩主要为长英质岩石。稀土元素特征参数的对比进一步表明,该黑色岩系的构造背景为大陆岛弧环境。综合研究揭示了该黑色岩系沉积于扬子地块西南缘的局限海盆,受到康滇古陆陆源碎屑、还原性沉积环境及海洋海底富金属热水的共同作用。本研究不仅增进了对筇竹寺组黑色岩系形成机制的理解,也为该地区矿产资源勘探提供了新的视角。The Early Cambrian black rock series,extensively developed in the eastern Yunnan region,represents a potential horizon for shale gas exploration and offers significant prospects for mineral explora-tion.This study focuses on the black rock series of the Qiongzhusi Formation from the Lower Cambrian in the Huize area,to elucidate its paleoenvironment,tectonic setting,and provenance through systematic sampling and rare earth element(REE)analysis,aiming to provide clues for mineral bed exploration and shale gas assessment.The study's findings indicate that the total content of rare earth elements(ZREE)in the black rock series ranges from 26.11×10^(-6)to 272.82×10^(-6),characterized by an enrichment of light rare earth elements and a relatively flat distribution of heavy rare earth elements.This pattern is further supported by moderate negative europium anomalies and slightly negative cerium anomalies,closely alig-ning with the typical upper continental crustal REE distribution.An upward increase in ZREE from the base to the top of the section suggests a climate that was predominantly warm and humid during the depo-sitional phase.The oCe and cerium anomaly indices indicate that the Qiongzhusi Formation formed in a deeper,anoxic aquatic environment.Additionally,the(Eu/Sm)_(N)-(Sm/Yb)_(N)bivariate plot and trace ele-ment signatures subtly suggest the influence of metalliferous hydrothermal activity on the black rock se-ries.A comprehensive assessment ofδEu,δCe,ΣREE,and supplementary geochemical parameters lead to a conclusion that the source rocks of the Qiongzhusi Formation black rock series are felsic rocks.The com-parative analysis of REE characteristic parameters further suggests that the tectonic setting of this black rock series is consistent with a continental island arc environment.The findings reveal that the black rock series deposited in a confined basin at the southwestern margin of the Yangtze block,influenced by clastic input from the Kangdian ancient land,a restricted sedimentary environment,and meta

关 键 词：筇竹寺组 黑色岩系 稀土元素 地球化学 

分 类 号：P618.13[天文地球—矿床学]