CAJ | 학술논문

分布于湖南东北部的石蛤蟆岩体侵位于新元古代地层中。由微细粒斑状黑云母花岗闪长岩和细粒斑状黑云母二长花岗岩等两期侵入体组成。通过锆石SHRIM PU--Pb法测得岩体侵位年龄为157土2Ma（2d），MSWD=0．98，成岩时代为晚侏罗世。SiO2=68．26％～68．53％，K2O／Na2O=1．37～1．59，岩石属镁质、准铝质-微过铝质、高钾钙碱性-钾玄岩系列；岩石明显富集大离子亲石元素，亏损高场强元素，Rb／Sr较低（0．40～0．56）；乏REE较高（171．48～183．81），Eu为弱负异常（δEu=0．86～0．93），（La／Yb）N=27．11～45．87；具较高的eNd值（-5．11）和高T2DM（1．63Ga）。综合研究表明，石蛤蟆花岗岩为混合源高钾钙碱性花岗岩类（KCG），其花岗岩浆有大量幔源物质加入。讨论认为岩体形成于构造体制转换下的地球动力学背景，是造山晚期张弛作用下的产物。
분포우호남동북부적석합마암체침위우신원고대지층중。유미세립반상흑운모화강섬장암화세립반상흑운모이장화강암등량기침입체조성。통과고석SHRIM PU--Pb법측득암체침위년령위157토2Ma（2d），MSWD=0．98，성암시대위만주라세。SiO2=68．26％～68．53％，K2O／Na2O=1．37～1．59，암석속미질、준려질-미과려질、고갑개감성-갑현암계렬；암석명현부집대리자친석원소，우손고장강원소，Rb／Sr교저（0．40～0．56）；핍REE교고（171．48～183．81），Eu위약부이상（δEu=0．86～0．93），（La／Yb）N=27．11～45．87；구교고적eNd치（-5．11）화고T2DM（1．63Ga）。종합연구표명，석합마화강암위혼합원고갑개감성화강암류（KCG），기화강암장유대량만원물질가입。토론인위암체형성우구조체제전환하적지구동역학배경，시조산만기장이작용하적산물。
Distributed in northeastern Hunan province and intruded in Neoproterozoic strata, Shihama granite pluton is mainly composed of micro-fine-grained porphyritic biotite granodiorites of early stage and fine- grained porphyritic biotite monzonitic granites of late stage. SHRIMP zircon dating of the granites gives an age of 157±2 Ma which belongs to Late Jurassic. The granites belong to magnesian, metaluminous-weak- ly peraluminous, high-K calc-alkaline-shoshonite series, with SIO2=68.26% -68.53M and K2O/Na2O= 1.37 - 1.59. The rocks show enriched large-ion lithophile elements, depleted high field-strength ele- ments, low values of Rb/Sr（0.40-0.56）, high values of ∑REE （171.48-183.81）, with δEu=0.86-- 0. 93, （La/Yb）N=27. 11-45.87, εNd=5.11, T2DM=1. 63 Ga. Studies indicate that the Shihama gran- ites belong to high-K calc-alkaline granites （KCG） originated form the crust-mantled mixed source ivolving large amount of mantle source materials. It is believed that the granite pluton is the result of tectonic ex- tension during the late period of orogenetic movement and is formed in the geodynamic background related to the transition of tectonic regime.