Zircon U-Pb geochronological framework of Qitianling granite batholith, middle part of Nanling Range, South China  

作　　者：ZHU JinChu WANG RuCheng ZHANG PeiHua XIE CaiFu ZHANG WenLan ZHAO KuiDong XIE Lei YANG Ce CHE XuDong YU APeng WANG LuBin 

机构地区：[1]State Key Laboratory for Mineral Deposits Research,School of Earth Sciences and Engineering,Nanjing University,Nanjing 210093,China

出　　处：《Science China Earth Sciences》2009年第9期1279-1294,共16页中国科学（地球科学英文版）

基　　金：Supported by National Natural Science Foundation of China (Grants Nos. 40730423, 40373014);Funds from the Ministry of Land and Resources (Grant No. 1212010632100)

摘　　要：The Qitianling granite batholith (QGB) is located in the southern Hunan Province, middle part of the Nanling Range, South China. Its total exposure area is about 520 km2. Based on our 25 single grain zircon U-Pb age data and 7 published data as well as the geological, petrological, and space distribution characteristics, we conclude that QGB is an Early Yanshanian (Jurassic) multi-staged composite pluton. Its formation process can be subdivided into three major stages. The first stage, emplaced at 163―160 Ma with a peak at about 161 Ma, is mainly composed of hornblende-biotite monzonitic granites and locally biotite granites, and distributed in the eastern, northern, and western peripheral parts of the pluton. The second stage, emplaced at 157―153 Ma with a peak at 157―156 Ma, is mainly composed of biotite granites and locally containing hornblende, and distributed in the middle and southeastern parts of the pluton. The third stage, emplaced at 150―146 Ma with a peak at about 149 Ma, is mainly composed of fine-grained (locally porphyritic) biotite granites, and distributed in the middle-southern part of the pluton. Each stage can be further disintegrated into several granite bodies. The first two intrusive stages comprise the major phase of QGB, and the third intrusive stage comprises the additional phase. Many second stage fine-grained granite bosses and dykes intruded into the first stage host granites with clear chilling margin-baking phenomena at their intrusive contacts. They were emplaced in the open fracture space of the earlier stage consolidated rocks. Their isotopic ages are mostly 2―6 Ma younger than their hosts. Conceivably, the time interval from magma emplacement, through cooling, crystallization, solidification, up to fracturing of the earlier stage granites cannot exceed 2―6 Ma. During the Middle-Late Jurassic in the Qitianling area and neighboring Nanling Range, the coeval granitic and basic-intermediate magmatic activities were widely developed. It indicates that the Early YanshanianThe Qitianling granite batholith (QGB) is located in the southern Hunan Province, middle part of the Nanling Range, South China. Its total exposure area is about 520 km2. Based on our 25 single grain zircon U-Pb age data and 7 published data as well as the geological, petrological, and space distribution characteristics, we conclude that QGB is an Early Yanshanian (Jurassic) multi-staged composite pluton. Its formation process can be subdivided into three major stages. The first stage, emplaced at 163-160 Ma with a peak at about 161 Ma, is mainly composed of hornblende-biotite monzonitic granites and locally biotite granites, and distributed in the eastern, northern, and western peripheral parts of the pluton. The second stage, emplaced at 157-153 Ma with a peak at 157-156 Ma, is mainly composed of biotite granites and locally containing hornblende, and distributed in the middle and southeastern parts of the pluton. The third stage, emplaced at 150-146 Ma with a peak at about 149 Ma, is mainly composed of fine-grained (locally porphyritic) biotite granites, and distributed in the middle-southern part of the pluton. Each stage can be further disintegrated into several granite bodies. The first two intrusive stages comprise the major phase of QGB, and the third intrusive stage comprises the additional phase. Many second stage fine-grained granite bosses and dykes intruded into the first stage host granites with clear chilling margin-baking phenomena at their intrusive contacts. They were emplaced in the open fracture space of the earlier stage consolidated rocks. Their isotopic ages are mostly 2–6 Ma younger than their hosts. Conceivably, the time interval from magma emplacement, through cooling, crystallization, solidification, up to fracturing of the earlier stage granites cannot exceed 2–6 Ma. During the Middle-Late Jurassic in the Qitianling area and neighboring Nanling Range, the coeval granitic and basic-intermediate magmatic activities were widely developed. It indicates that the Early Yanshanian period

关 键 词：NANLING RANGE Qitianling GRANITE BATHOLITH (QGB) zircon U-PB dating intrusion stages GRANITE body DISINTEGRATION 

分 类 号：P597.3[天文地球—地球化学]