Petrogenesis and metallogenesis of the Yanshanian adakite-like rocks in the Eastern Yangtze Block  

作　　者：王强 赵振华 许继峰 李献华 包志伟 熊小林 刘义茂 

机构地区：[1]Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China

出　　处：《Science China Earth Sciences》2003年第z1期164-176,共13页中国科学（地球科学英文版）

基　　金：supported by the National Climbing Program of China(Grant No.95-Y-25);the National Natural Science Foundation of China(Grant Nos.40273019 and 40172028);the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant Nos.KZCX2-102 and KZCX2-SW-117);the Major State Basic Research Program of China(Grant No.G1999043202).

摘　　要：Many of the Yanshannian intermediate-acid intrusive rocks related to Cu-Au mineraliza-tion in the Eastern Yangtze Block are characterized by high Al2O3, Sr contents, while low in Y, Yb contents, thus with high Sr/Y, and La/Yb ratios, and variational isotope signatures in particular, e.g. e Nd( t ) = -11.92—1.96, (143Nd/144Nd)i = 0.5120—0.5125, TDM = 0.70—1.71 Ga, (87Sr/86Sr)i = 0.7043—0.7076. The geochemical characteristics of these rocks suggest that: (1) these rocks are geo-chemically similar to adakite, which might have been stemmed from the partial melting of thick-ened basaltic lower crust due to basalt underplating; and (2) the high pressure (1.2—4.0 GPa) and high temperature (850—1150℃) surroundings of the lower crust favor both the fluid and ada-kite-like magma to generation. Not only can the adakite-like magma carry abundant fluid and Cu-Au ore-froming materials, but also can it bring them to the shallow part with ease and contrib-utes to the Cu-Au mineralization.Many of the Yanshannian intermediate-acid intrusive rocks related to Cu-Au mineraliza-tion in the Eastern Yangtze Block are characterized by high AI2O3, Sr contents, while low in Y, Yb contents, thus with high Sr/Y, and La/Yb ratios, and variational isotope signatures in particular, e.g. εNd(t) = -11.92-1.96, (143Nd/144Nd): = 0.5120-0.5125, TDM= 0.70-1.71 Ga, (7Sr/86Sr), = 0.7043 -0.7076. The geochemical characteristics of these rocks suggest that: (1) these rocks are geo-chemically similar to adakite, which might have been stemmed from the partial melting of thick-ened basaltic lower crust due to basalt underplating; and (2) the high pressure (1.2-4.0 GPa) and high temperature (850-1150℃) surroundings of the lower crust favor both the fluid and ada-kite-like magma to generation. Not only can the adakite-like magma carry abundant fluid and Cu-Au ore-froming materials, but also can it bring them to the shallow part with ease and contrib-utes to the Cu-Au mineralization.

关 键 词：ADAKITE Cu-Au metallogenesis UNDERPLATING Yanshanian Period Yangtze Block. 

分 类 号：P581[天文地球—岩石学]