CAJ | 학술논문

新街岩体位于昌宁-孟连带北段,主要岩性为二长花岗岩.LA-ICP-MS锆石U-Pb定年结果表明,新街岩体侵位于约82Ma.岩体SiO2含量为74.28%~75.17%,富钾(K2O/Na2O=1.44~1.73)和较低钙CaO(0.37%~0.41%),铝饱和指数(A/CNK)为1.121~1.156,富集Rb、Th、K、LREE等元素,相对亏损Nb、Ta、Ti、Zr、Hf等高场强元素.这些特征表明,新街岩体属于强过铝质S型花岗岩.新街岩体负且变化范围大的锆石εHf(t)值(-16.9~-0.5)和古老的Hf同位素地壳模式年龄(1.19~2.28Ga),表明其主要来源于古老地壳物质的重熔,并有不同程度的幔源物质加入.由于喜马拉雅新特提斯洋封闭发生在65Ma左右,新街岩体很可能是在喜马拉雅新特提斯洋洋壳俯冲的地球动力学背景下形成的.
신가암체위우창저-맹련대북단,주요암성위이장화강암.LA-ICP-MS고석U-Pb정년결과표명,신가암체침위우약82Ma.암체SiO2함량위74.28%~75.17%,부갑(K2O/Na2O=1.44~1.73)화교저개CaO(0.37%~0.41%),려포화지수(A/CNK)위1.121~1.156,부집Rb、Th、K、LREE등원소,상대우손Nb、Ta、Ti、Zr、Hf등고장강원소.저사특정표명,신가암체속우강과려질S형화강암.신가암체부차변화범위대적고석εHf(t)치(-16.9~-0.5)화고로적Hf동위소지각모식년령(1.19~2.28Ga),표명기주요래원우고로지각물질적중용,병유불동정도적만원물질가입.유우희마랍아신특제사양봉폐발생재65Ma좌우,신가암체흔가능시재희마랍아신특제사양양각부충적지구동역학배경하형성적.
The Xinjie granite body is located in the north of the Changning-Menglian suture zone. The rock type is mainly monzo-granite. LA-ICP-MS zircon U-Pb dating indicates that the Xinjie granite body was emplaced at about 82Ma of Late Cretaceous. The major element chemical data of the Xinjie granites show that SiO2 values vary from 74.28%to 75.17%, with high K2O (K2O/Na2O=1.44~1.73), low CaO (0.37%~0.41%) content, and A/CNK 1.10~1.22. The Xinjie granite body displays obvious enrichment of Rb, Th, K and LREE, and relatively negative anomalies of HFSE such as Nb, Ta, Ti, Zr and Hf. It is suggested that the Xinjie intrusion be-longs to peraluminous S-type granite. The negativeεHf(t) values are distributed in a wide range (-16.9~-0.5), which, together with ancient Hf-isotope crust model age (1.19~2.28Ga), indicates that the intrusion mainly originated from re-melted ancient crust materi-als with the addition of varying degrees of mantle materials. The partial melting was related to the subduction of Neo-Tethyan plate.