摘要
摘要：桂东南南渡正长岩的LA—ICP—MS锆石u—Pb年代学测试表明，该正长岩形成年龄为162±1Ma，和赣南全南及桂东南地区其他燕山早期正长岩形成年龄一致。该正长岩SiO2=61．78％～63．39％，具有高碱（K：O＋Na：O=11．18％～12．30％）、高K，O含量（6．47％一9．06％）和K，O／Na。O值（1．37～2．80）特征，系钾玄质系列岩石。该正长岩富集轻稀土元素（LREE）和大离子亲石元素（LILE）、Eu负异常（gEu=0．48～0．74）、sr和P-Ti负异常明显、无明显Nb—Ta异常、st/d（t）=＋0．32～＋0．84，被归为大陆板内钾玄质岩石，代表了燕山早期160Ma左右华南内部一次重要的伸展一裂谷事件。
The Nandu syenite shows SiO2= 62. 7% ～ 64. 2%,K2O + Na2O = 11. 2% Wang Y.1994.The Kuiqi peralkaline granitic complex(SE China):Petrology and geochemistry.Journal of Petrology,35(4):983-1015.
12. 3%,K2O = 6. 47% ～ 9. 06% with high K2O / Na2O of 1. 37 ～ 2. 80. It can be defined as shoshonitic series rocks. These rocks are characterized by enrichment of LREE and LILE,with slight Eu negative anomalies( δEu = 0. 48 ～ 0. 74),and significant Sr and P-Ti negative anomalies but insignificant Nb-Ta negative anomalies. Their εNd( t) values range from+ 0. 32 to + 0. 84. Such signatures show an affinity to intraplate shoshonitic rocks. LA-ICP-MS zircon U-Pb dating of the Nandu syenite yields an age of 162 ± 1 Ma with MSWD = 0. 1( n = 23),which is interpreted as the crystallization age. Such an age is consistent with those in southeast Guangxi and south Jiangxi provinces. Our new data,together with the available data,indicate a middle Jurassic intraplate extensional tectonic regime in South China.
出处
《大地构造与成矿学》
EI
CAS
CSCD
北大核心
2013年第2期284-293,共10页
Geotectonica et Metallogenia
基金
国家自然科学基金(批准号:40902062,408256009)
中国科学院重大项目(编号:KZCX1-YW-15-1)
湖南省教育厅青年项目(编号:12B039)联合资助
