| 湘中印支期关帝庙岩体地球化学特征及成因 |
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| 引用本文： | 柏道远,钟响,贾朋远,熊雄,黄文义.湘中印支期关帝庙岩体地球化学特征及成因[J].沉积与特提斯地质,2014(4):92-104. |
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| 作者姓名： | 柏道远 钟响 贾朋远 熊雄 黄文义 |
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| 作者单位： | 湖南省地质调查院,湖南长沙410016 |
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| 基金项目： | 中国地质调查局“湖南1：25万武冈市和永州市幅区调修测”项目（1212011120793）、“中国地质构造区划综合研究与区域地质志修编”项目（1212010811032）联合资助 |
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| 摘 要： | 关帝庙岩体位于湘中盆地,据年龄资料可分为中三叠世末和晚三叠世中期两个形成时期。中三叠世花岗岩中发育闪长质暗色微粒包体,自早至晚依次为细中粒角闪石黑云母花岗闪长岩、细中粒斑状角闪石黑云母二长花岗岩、细-细中粒(斑状)黑云母二长花岗岩。晚三叠世花岗岩自早至晚依次为细中粒-粗中粒斑状二云母二长花岗岩、细粒二云母二长花岗岩。岩石高硅、富铝、高钾,(Na2O+K2O)含量为6.80%~8.87%,平均7.74%;K2O/Na2O比值在1.35~2.66之间,平均为1.58;ASI值为0.99~1.40。总体属镁质、高钾钙碱性系列过铝质花岗岩类。中三叠世花岗岩Ba、Nb、Sr、P、Ti表现为明显亏损,Rb、(Th+U+K)、(La+Ce)、Nd、(Zr+Hf+Sm)、(Y+Yb+Lu)等则相对富集。中、晚三叠世花岗岩ΣREE含量为121.60~197.56μg/g,平均为158.70μg/g;δEu值0.28~0.68,平均为0.53;(La/Yb)N值为5.94~17.53,平均13.80。中三叠世花岗岩ISr值为0.71302~0.71758,εSr(t)值为121~186,εNd(t)值为-9.95~-8.74,t2DM为1.72~1.82Ga。C/MF-A/MF图解显示源岩主要为碎屑岩、少量基性岩和泥质岩。地质地球化学特征表明,印支期关帝庙花岗岩属S型花岗岩,形成于碰撞-后碰撞构造环境。
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| 关 键 词： | 地球化学特征 S型花岗岩 中三叠世 晚三叠世 印支运动 关帝庙岩体 湘中 |
| 收稿时间： | 2014/2/13 0:00:00 |
| 修稿时间： | 2014/2/17 0:00:00 |
Geochemistry and petrogenesis of the Indosinian Guandimiao granitic pluton in central Hunan |
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| BAI Dao-yuan,ZHONG Xiang,JIA Peng-yuan,XIONG Xiong,HUANG Wen-yi.Geochemistry and petrogenesis of the Indosinian Guandimiao granitic pluton in central Hunan[J].Sedimentary Geology and Tethyan Geology,2014(4):92-104. |
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| Authors: | BAI Dao-yuan ZHONG Xiang JIA Peng-yuan XIONG Xiong HUANG Wen-yi |
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| Institution: | (Hunan Institute of Geological Survey, Changsha 410016, Hunan, China) |
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| Abstract: | The Indosinian Guandimiao granitic pluton in central Hunan is composed of two generations： the latest Middle Triassic and middle Late Triassic granites. The Middle Triassic granites comprise meladioritic micrinites, and consist, in a progressively younger order, of fine- to medium-grained hornblende-biotite granodiorite, fine- to medium-grained porphyritic hornblende-biotite adamellite, and fine- to finely medium-grained （porphyritic） biotite adamellite. The Late Triassic granites consist, in a progressively younger order, of finely medium-grained to coarsely medium-grained porphyritic two-mica adamellite and fine-grained two-mica adamellite. Geochemically, these granites are characterized by high Si, enriched A1, high K, moderate alkali contents, SiO2 contents ranging from 69.50% to 74.53% with an average of 71.68%. The Late Triassic granites have Al2O3 contents from 13. 39% to 16.31% with an average of 14.62% ; K20 contents from 4.15% to 6.45% with an average of 4.71% total alkali （ Na2O ＋ K2O） contents from 6.80% to 8.87% with an average of 7.74% ; K2O/Na2O ratios from 1. 35 to 2.66 with an average of 1.58 ; ASI values from 0.99 to 1.40, indicating the magnesian high-K eale-alkaline peraluminous granites. The Middle Triassic granites are remarkedly depleted in Ba, Nb, Sr, P and Ti, and relatively enriched in Rb, Th ＋ U ＋ K, La ＋ Ce, Nd, Zr ＋ Hf ＋ Sm and Y ＋ Yb ＋ Lu. The EREE contents for the Middle and Late Triassic granites vary from 121.60 to 197.56p, g/g with an average of 158.70μg/g; δEu values from 0.28 to 0.68 with an average of 0.53, and （La/Yb） N values from 5.94 to 17.53 with an average of 13.80. The above-mentioned geological and geochemical signatures show that the Indosinian Guandimiao granites belong to the S-type granites generated in the collision-postcollision tectonic settings. |
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| Keywords: | geochemistry S-type granite Middle Triassic Late Triassic Indosinian orogeny Guandimiao granitic pluton central Hunan |
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