伊朗南部Lurestan-Khuzestan地区中新统沉积物源特征  

Miocene Sedimentary Characteristics and Provenance Analysis in the Lurestan-Khuzestan Region,Southern Iran

作　　者：孙高远 崔希超 陈嘉诺 蒋璟鑫 胡修棉[2] 王亚苏 SUN GaoYuan;CUI XiChao;CHEN JiaNuo;JIANG JingXin;HU XiuMian;WANG YaSu(College of Oceanography,Hohai University,Nanjing 210024,China;State Key Laboratory of Mineral Deposit Research,School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China)

机构地区：[1]河海大学海洋学院,南京210024 [2]南京大学内生金属矿床成矿机制研究国家重点实验室,地球科学与工程学院,南京210023

出　　处：《沉积学报》2024年第5期1653-1669,共17页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(42072124)。

摘　　要：【目的】阿拉伯和欧亚大陆碰撞导致了扎格罗斯造山带和前陆盆地的形成。扎格罗斯前陆盆地的持续充填致使海水最终从这一地区退出,实现了由海到陆的转变过程,从而为探讨新特提斯洋的消亡提供约束。【方法】对伊朗扎格罗斯Lurestan地区和Khuzestan地区的中新统Agha Jari组进行了系统的地层学、沉积学、砂岩岩石学和碎屑锆石U-Pb年代学研究,以揭示碎屑物质充填和海退过程。【结果】Lurestan地区Agha Jari组由中到厚层砂—泥岩互层组成,沉积环境分析其形成于河流环境。碎屑组分显示大量变质岩岩屑,结合170 Ma锆石年龄峰,指示盆地北侧Sanandaj-Sirjan岩浆变质带为其可能物源;Khuzestan地区Agha Jari组主要为底部钙质砂岩,向上逐渐变为厚层砂岩、泥岩组合,沉积于三角洲环境。砂岩碎屑组分以沉积岩屑为主,中生代锆石年龄与扎格罗斯褶皱冲断带一致,表明碎屑物源主要为再旋回的扎格罗斯褶皱冲断带中的沉积岩。基于下伏Gachsaran-Mishan组浅海蒸发岩和碳酸盐岩沉积,Agha Jari组记录了扎格罗斯前陆盆地由海向陆的转变过程。生物地层学资料约束残留海消亡的时间为不早于中新世早期,并且存在从西北向东南海退的趋势。【结论】阿拉伯—欧亚大陆初始碰撞作用导致扎格罗斯山脉隆起,随着持续隆升的扎格罗斯山脉向前陆盆地提供碎屑物质是导致扎格罗斯残留海关闭的直接原因,并且扎格罗斯残留海从西北向东南退出的古地理格局至少在中新世已经形成。[Objective]The collision of the Arabian-Eurasian Plates led to the formation of the Zagros orogenic belt and related foreland basin.The gradual filling of the Zagros foreland basin resulted in the retreat of the Neo-Tethys Ocean in the Zagros region,which caused the transition from the marine to terrestrial environments.This process provides the chance to explore the demise of the Neo-Tethyan Ocean in the Middle East.[Methods]In this study,we conducted detailed stratigraphy,sedimentology,sandstone petrography,and detrital zircon U-Pb age determination on the Miocene sedimentary strata in the Lurestan and Khuzestan regions of the Zagros Mountains in southern Iran,which provide new constraints on the filling of the Zagros foreland basin and the regression process of the Neo-Tethys Ocean in the Zagros region.[Results]The Agha Jari Formation in the Lurestan region is characterized by largescale,medium-to-thick layered sandstones interbedded with mudstones.Sedimentary environment analysis suggests that it has been formed in a fluvial environment.The sandstone petrography shows a significant number of metamorphic clasts.Combined with the detrital zircon U-Pb age peak of Jurassic~170 Ma,the Agha Jari Formation in the Lurestan region is found to be derived from the Sanandaj-Sirjan zone to the north.The Agha Jari Formation in the Khuzestan area is a large set of thick mudstone beds,thick mudstone interbedded with sandstone,thick sheeted sandstone interbedded with mudstone,and sand-mudstone interbeds.The sedimentary environment analysis shows that it has been formed in a transitional deltaic environment.The sandstone modal composition indicates that the clasts of the sedimentary rocks occurred.The detrital zircon ages show Mesozoic ages,comparable with the Zagros Fold-and-Thrust Belt.Thus,they have been mainly recycled from the sedimentary strata in Zagros Fold-and-Thrust Belt.Based on the underlying Gachsaran-Mishan Formations,which are composed of shallow marine limestone and evaporite,the Agha Jari Formation represents

关 键 词：新特提斯洋 扎格罗斯 Agha Jari组 沉积环境 海退 

分 类 号：P512.2[天文地球—地质学]