大别造山带姚冲花岗岩岩石地球化学特征及其地质意义
发布时间：2018-10-05 08:48
【摘要】：姚冲岩体位于秦岭-大别山造山带上,岩体的主要岩性为黑云母花岗岩和花岗斑岩。岩石地球化学分析结果显示,姚冲岩体SiO_2含量为71.28%~77.24%,K_2O含量为3.81%~5.28%,Na_2O含量为3.76%~5.03%,Al_2O_3含量为11.61%~14.6%,具有高钾钙碱性和准铝质-过铝质(A/CNK=0.96~1.03)特征。岩石稀土元素总量较低(11.82×10~(-6)~123.65×10~(-6)),轻稀土元素相对富集,重稀土元素相对亏损,具有Eu负异常,岩体富集Rb、U、Hf和Y,亏损Ba、Nb、Ta和Ti,显示出I型花岗岩的特点。锆石Hf同位素分析结果表明,姚冲岩体的ε_(Hf)(t)值为-30~-22.8,位于地幔演化线之下,t_(DM2)值变化于2.21~2.60Ga之间,指示其源于扬子板块北缘的古老地壳,其组成类似于扬子板块北缘TTG型岩浆岩。结合区域地质背景,姚冲岩体形成于扬子陆块与华北陆块碰撞造山后的陆内伸展环境,对应的地球动力学背景为晚侏罗世—早白垩世地壳从挤压收缩向区域性伸展的构造体制大转换过程。
[Abstract]:The Yaochong rock body is located on the Qinling-Dabie orogenic belt. The main lithology of the rock body is biotite granite and granitic porphyry. The results of petrogeochemical analysis show that the SiO_2 content of the Yaochong rock body is 71.28 and 77.240.The content of K _ 2O is 3.81 and 5.28 and the content of Na _ 2O is 3.760.The content of Al _ 2O _ 2O _ 3 is 11.61 ~ 14.6cm, which is characterized by high potassium calc-alkaline and quasi-aluminum-peraluminous (A/CNK=0.96~1.03). The total amount of rare earth elements in rocks is relatively low (11.82 脳 10 ~ (-6) ~ (123.65) 脳 10 ~ (-6), light rare earth elements are relatively enriched, heavy rare earth elements are relatively depleted, and have negative Eu anomalies. The rock masses are enriched in Rb,U,Hf and Y, and depleted in Ba,Nb,Ta and Ti, show the characteristics of I-type granites. The results of zircon Hf isotopic analysis show that the 蔚 _ (Hf) (t) value of the Yaochong rock body is -30 ~ 22.8, which is located between 2.21~2.60Ga and the mantle evolution line, indicating that it originated from the ancient crust of the northern margin of the Yangtze plate, and its composition is similar to that of the TTG type magmatic rock in the northern margin of the Yangtze plate. Combined with the regional geological background, the Yaochong rock body was formed in the intracontinental extensional environment after the collision orogeny between the Yangtze and North China landmasses. The corresponding geodynamic background is a great transformation process of the tectonic system from the compressional contraction to the regional extension of the crust from late Jurassic to early Cretaceous.
【作者单位】： 中南大学资源与安全工程学院;中南大学有色金属成矿预测教育部重点实验室;中南大学地球科学与信息物理学院;河南省有色金属地质矿产局第七地质大队;河南省有色金属地质勘查总院;
【基金】：中国地质调查局项目《豫南大别山北麓地区钼多金属成矿规律及找矿方法研究》(编号:12120113091200);中国地质调查局项目《湖南省花垣-凤凰铅锌矿整装勘查区关键基础地质研究》(编号:12120114052201) 湖南省国土资源科研项目《湖南浏阳-醴陵官庄金矿整装勘查区找矿勘查关键基础地质研究》(编号:2016-04)
【分类号】：P588.121
本文编号：2252748
[Abstract]:The Yaochong rock body is located on the Qinling-Dabie orogenic belt. The main lithology of the rock body is biotite granite and granitic porphyry. The results of petrogeochemical analysis show that the SiO_2 content of the Yaochong rock body is 71.28 and 77.240.The content of K _ 2O is 3.81 and 5.28 and the content of Na _ 2O is 3.760.The content of Al _ 2O _ 2O _ 3 is 11.61 ~ 14.6cm, which is characterized by high potassium calc-alkaline and quasi-aluminum-peraluminous (A/CNK=0.96~1.03). The total amount of rare earth elements in rocks is relatively low (11.82 脳 10 ~ (-6) ~ (123.65) 脳 10 ~ (-6), light rare earth elements are relatively enriched, heavy rare earth elements are relatively depleted, and have negative Eu anomalies. The rock masses are enriched in Rb,U,Hf and Y, and depleted in Ba,Nb,Ta and Ti, show the characteristics of I-type granites. The results of zircon Hf isotopic analysis show that the 蔚 _ (Hf) (t) value of the Yaochong rock body is -30 ~ 22.8, which is located between 2.21~2.60Ga and the mantle evolution line, indicating that it originated from the ancient crust of the northern margin of the Yangtze plate, and its composition is similar to that of the TTG type magmatic rock in the northern margin of the Yangtze plate. Combined with the regional geological background, the Yaochong rock body was formed in the intracontinental extensional environment after the collision orogeny between the Yangtze and North China landmasses. The corresponding geodynamic background is a great transformation process of the tectonic system from the compressional contraction to the regional extension of the crust from late Jurassic to early Cretaceous.
【作者单位】： 中南大学资源与安全工程学院;中南大学有色金属成矿预测教育部重点实验室;中南大学地球科学与信息物理学院;河南省有色金属地质矿产局第七地质大队;河南省有色金属地质勘查总院;
【基金】：中国地质调查局项目《豫南大别山北麓地区钼多金属成矿规律及找矿方法研究》(编号:12120113091200);中国地质调查局项目《湖南省花垣-凤凰铅锌矿整装勘查区关键基础地质研究》(编号:12120114052201) 湖南省国土资源科研项目《湖南浏阳-醴陵官庄金矿整装勘查区找矿勘查关键基础地质研究》(编号:2016-04)
【分类号】：P588.121
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