福建闽江和九龙江现代沉积物重矿物特征及其物源意义  

Characteristics of heavy minerals in modern sediments of Minjiang and Jiulongjiang Rivers,Fujian Province and their provenance implication

作　　者：陈心怡 黄奇瑜 邵磊[1] Chen Xin-Yi;Huang Chi-Yue;Shao Lei(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092;Department of Earth Sciences,National Cheng Kung University,Tainan 701,Taiwan)

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092 [2]国立成功大学地球科学系

出　　处：《古地理学报》2018年第4期637-650,共14页Journal of Palaeogeography：Chinese Edition

基　　金：国家自然科学基金项目(编号:41576059);国家自然科学基金联合基金项目(编号:U1505231);国家科技重大专项项目(编号:2016ZX05026-004);中央高校基本科研业务费专项资金资助~~

摘　　要：通过对闽江和九龙江沿岸沉积物中重矿物的分析,发现重矿物组合与源区岩石具有极好的相关性。两条河流流域重矿物组合为不透明铁矿类—绿帘石—锆石—电气石—角闪石,特征矿物为绿帘石,含量高达原生透明重矿物比重的70%,其成因除与高级变质岩有关外,还与中酸性岩浆岩及其与围岩接触蚀变发生的绿帘石化有关。从重矿物组合、重矿物特征指数以及与锆石年龄谱系的比对分析发现,闽江流域重矿物源自闽西北武夷山前寒武纪的变质岩、闽东广泛出露的燕山期岩浆岩和接触变质岩,而九龙江流域重矿物源自闽西南的印支—燕山期花岗岩。闽江上游沉积物重矿物以源自高级变质岩的重矿物为特征,中下游由上游来源的重矿物和下游酸性岩浆岩及接触变质岩形成的重矿物共同构成;九龙江以印支—燕山期花岗岩中的副矿物组合为特征。研究结果显示,对于中小流域面积的河流,由于搬运距离有限,重矿物组合保存的源岩信息量大,可作为研究流域内构造演化和源汇对比的重要手段。Analyses of this study revealed that the heavy mineral assemblages in the sediments along the Minjiang River and Jiulongjiang River and the rock types in their adjacent provenance areas are highly correlated.The heavy mineral assemblages in drainage areas of Minjiang and Jiulongjiang Rivers are characterized by opaque Fe oxide minerals,epidote,zircon,tourmaline,and hornblende,with epidote accounting for up to 70%among the primary transparent minerals.Except for the reason of high-grade metamorphism of these rocks,the high epidote content is also associated with the contact metamorphic zone between acid granite intrusion and surrounding rocks.According to the analysis of heavy mineral assemblages,provenance-sensitive index,and U-Pb dating of detrital zircon,heavy minerals in the drainage area of Minjiang River were interpreted to be derived from the Precambrian rocks in the Wuyishan Mountain in northwestern Fujian,Yanshannian magmatite and contact metamorphic rocks in eastern Fujian,and heavy minerals in the drainge area of Jiulongjiang River were derived from Indosinian-Yanshanian granite in southwestern Fujian.Sediments in the upper Minjiang River contain heavy minerals characteristic of high-grade metamorphic parent rocks.Heavy minerals in the sediments in the middle and lower Minjiang River are derived from magmatic rocks,contact metamorphic rocks,and from upper reaches of the river.The heavy minerals in Jiulongjiang River are mainly from Indosinian-Yanshanian granite in southwestern Fujian.This research shows that in rivers with small to medium drainage areas,due to the limited transport distance,the provenance information can be largely preserved in the heavy mineral assemblages.Analysis of heavy minerals can therefore yield crucial information for reconstructions of tectonic evolution and source-to-sink analysis.

关 键 词：福建 闽江 九龙江 重矿物 物源分析 碎屑锆石 

分 类 号：P512.22[天文地球—地质学]