摘要
湘东南花岗岩带位于南岭花岗岩带中段,包含以千里山、骑田岭等为代表的花岗岩类和以水口山、铜山岭及宝山为代表的花岗闪长岩类。黄沙坪花岗岩体与前者相邻产出,在岩石地球化学上也具有相类似的特征,其主量元素表现为高硅、高钾、高K2O／Na2O比值,低磷,微量元素以富集Rb、Th、U、K、Ta、Nb,贫Ba、Sr、P、Eu、Ti为特征,具有明显的Eu负异常。利用LA-ICP-MS锆石U-Pb原位定年方法,测得黄沙坪花岗岩的年龄为161．6±1．1Ma,也与区内千里山(162．55±3．25Ma)、骑田岭(161±2Ma)等花岗岩岩体的年龄基本一致,代表了湘东南乃至南岭地区燕山期花岗岩的主要形成时期。因此本文认为,黄沙坪花岗岩体与千里山、骑田岭等岩体属于同一类型,岩石成因可能与印支造山运动后的岩石圈伸展有关,形成于地壳物质的部分熔融;而与水口山、铜山岭和宝山等花岗闪长质岩体有较明显差异。
There are two types granitoid in the middle of Nanling granitoid zone, including Qianlishan and Qitianling granites and Shuikoushan, Tongshanling and Baoshan granodiorite intrusions. The Huangshaping granite, which is close to the former granites, is characterized by higher values of SiO2 and K20, higher ratio of K20/Na2O, high abundances of Rb, Th, U, Ta and Nb, but lower contents of Ba, St, P, Eu and Ti. Chondrite-normalized REE patterns show strong negative Eu anomalies. The Huangshaping granite is dated 161.6 1- 1 Ma by zircon LA-ICPMS U-Pb method, which is in accordance with ages of the Qianlishan（ 162.55±3.25Ma） and Qitianling （ 161±2Ma）granites. These ages imply a major emplacement period of the Yanshanian granites in southeast Hunan province as well as the whole Nanling Range area. In this study, the geochemical and geochronological characteristics are similar between Huangshaping granite and the Qianlishan and Qitianling granites. They are the same type granitoid. Their lithogenesis was related to the lithospheric extension after the Indosinian Orogenesis, and formed from partial melting of the crust material. All this are different from granodiorite intrusions in Shuikoushan, Tongshanling and Baoshan.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2005年第3期688-696,共9页
Acta Petrologica Sinica
基金
国家重点基础研究发展规划研究项目(1999CB403209)国家自然科学基金重点项日(40132010)资助
