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湘东南宝峰仙地区燕山早期花岗岩地球化学特征及其构造环境
引用本文:江西根,柏道远,陈建超,熊延望,马铁球,王先辉.湘东南宝峰仙地区燕山早期花岗岩地球化学特征及其构造环境[J].大地构造与成矿学,2006,30(2):206-219.
作者姓名:江西根  柏道远  陈建超  熊延望  马铁球  王先辉
作者单位:湖南省地质调查院,湖南,长沙,410011
基金项目:中国地质调查局区域地质调查项目(200213000035)资助.
摘    要:湘东南宝峰仙地区发育有3个小规模花岗岩体,均为黑云母二长花岗岩。黑云母40Ar/39Ar法坪年龄为(156.8±1.8)Ma。ISr值为0.71296~0.71347,εNd(t)值为-7.3~-7.2,t2DM为1.54Ga,成岩物质源自中元古代地壳,并有地幔物质的混染。岩石为准铝质,A/CNK=0.98~1.08,平均1.02;富钾和硅,其氧化物平均值分别为5.34%和74.51%;贫Ti、Mg和Ca,其氧化物平均含量分别为0.18%、0.18%和0.98%,属高钾钙碱性系列。具有明显的Ba、Sr、P、Ti负异常和U、Ta、La、Ce、Nd、Sm、Y正异常;富含稀土元素(平均339.14μg/g)。地球化学特征及区域构造演化背景等表明岩石形成于挤压造山向非造山转换的后造山拉张环境。

关 键 词:宝峰仙  花岗岩  黑云母~(40)Ar/~(39)Ar法定年  地球化学特征  后造山环境  湘东南
文章编号:1001-1552(2006)02-0206-14
收稿时间:2005-01-20
修稿时间:2005-04-20

GEOCHEMICAL CHARACTERISTICS AND TECTONIC SETTING OF BAOFENGXIAN EARLY YANSHANIAN GRANITES, SOUTHEAST HUNAN
JIANG Xigen,BAI Daoyuan,CHEN Jianchao,XIONG Yanwang,MA Tieqiu,WANG Xianhui.GEOCHEMICAL CHARACTERISTICS AND TECTONIC SETTING OF BAOFENGXIAN EARLY YANSHANIAN GRANITES, SOUTHEAST HUNAN[J].Geotectonica et Metallogenia,2006,30(2):206-219.
Authors:JIANG Xigen  BAI Daoyuan  CHEN Jianchao  XIONG Yanwang  MA Tieqiu  WANG Xianhui
Abstract:Three small-scale granitic intrusions occur in Baofengxian area, east south Hunan province, they are composed of biotite monzogranites and show a 40 Ar/ 39 Ar plateau age of (156.8±1.8) Ma. The intrusions demonstrate I_ Sr value of 0.71296~0.71347, ε_ Nd (t) value of-7.3~-7.2 and t_ 2DM age of 1.54 Ga, which indicate that they were derived from Mesoproterozoic continental crust, and were intermingled with mantle source. The rocks are metaluminous (A/CNK=0.98~1.08, with an average of 1.02), and are rich in K_2O (5.34% on the average) and SiO_2 (74.51%), and show lower contents of TiO_2 (0.18% on the average), MgO (0.18%) and CaO ( 0.98% ), and characteristics similar to those of high-K calc-alkaline granitoids. The trace elements geochemistry was characterized by evidently negative anomaly of Ba, Sr, P, Ti, positive anomaly of U, Ta, La, Ce, Nd, Sm, Y and abundant amount of REE (total REE: 339.14μg/g on the average). Geochemical characteristics and regional tectonic evolution background indicate that the rocks were formed in a post-orogenic extension environment.
Keywords:Baofengxian  granite  biotite ~(40)Ar/~(39)Ar dating  geochemical characteristics  post-orogenic environment  southeast Hunan
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