安徽沿江江南晚中生代岩浆-成矿年代学格架  

A GEOCHRONOLOGICAL FRAMEWORK OF LATE MESOZOIC MAGMATISM AND METALLOGENESIS IN THE LOWER YANGTZE VALLEY, ANHUI PROVINCE

作　　者：陈江峰[1] 喻钢[1] 杨刚[1] 杨胜洪[1] 

机构地区：[1]中国科学技术大学,地球和空间科学学院,安徽,合肥,230026

出　　处：《安徽地质》2005年第3期161-169,共9页Geology of Anhui

摘　　要：根据新的较为可靠的同位素地质年代学数据,长江中下游金属成矿带中段(安徽段)的中生代岩浆-成矿作用可大致分为3期:135到145 Ma一期包括铜陵、月山以及江南广大地区的侵入岩和与之有关矿床,也包括江北的属于A型花岗岩带的大龙山石英正长岩.庐枞和宁芜盆地的火山岩形成于127到131 Ma,但赋存于火山岩中的铁矿床中钠长石给出的40Ar-39A,年龄却在122到126 Ma.最年轻的一组年龄为约126到120Ma,包括江南广大地区的花岗岩和宁芜地区的辉长质小侵入体.晚侏罗世以来的突发性岩石圈去根作用以及太平洋板块向西俯冲导致扬子与华北间的岩石圈边界的南北向拉张,都可能引发地幔上涌,并进一步导致地壳熔融和大规模的复杂的岩浆和成矿作用.Based on new reliable geochronological data, three periods of Late Mesozoic magmatism and metallogenesis are recognized in the middle part of the Middle-Lower Ynagtze Metallogenic belt（Anhui province）. At 135 to 145Ma, intrusives and associated ore deposits from Tongling, Yueshan, southen, Anhui districts and Dalongshan quartz syenite showing A type granite affinity were formed. Volcanic rocks in the Luzong and Ningwu basins were formedat 127 to 131 Ma, however, albites from Fe deposist hosted by volcanic rocks gives ^40Ar-^39Ar ages of 122 to 126Ma. The youngest magmatism took place at 122 to 126Ma, forming granites in southern Anhui district and small gabbroic intrusions in the Ningwu district. Removal of the thick lithosphere in the lower Yangtze region at Late Jurassic might cause upwelling of themantle-derived basalt and further induce melting of the crust. North-south extension caused by westward subduction of the Pacific plate might induce basaltic magmatism and crustal melting along the 1 ithospheric boundary between the North China and Yangtze blocks. Both tectonic models can exolain the genesis of the igneous rocks and associated depostis of the region studied.

关 键 词：同位素地质年代学 岩浆岩 成矿 长江中下游 安徽 晚中生代 安徽段 成矿年代学 岩浆 江南 同位素地质年代学 岩石圈边界 格架 沿江 

分 类 号：P542.3[天文地球—构造地质学] TV882.3[天文地球—地质学]