CAJ | 학술논문

安徽泾县榔桥花岗闪长岩体为分布于皖南台褶带北缘壳幔同熔型复式岩体。该岩体主侵入期两个花岗闪长岩样品和侵入后期脉岩一个花岗斑岩样品的锆石 U-Pb 年龄分别为135．6±1．8Ma，137．6±2．0Ma，136．4±1．9Ma，显示岩体形成于早白垩世。锆石 Hf同位素分析表明榔桥岩体可能由中元古代地壳物质部分熔融形成，同时混染有少量古元古代地壳物质。根据全岩Zr含量计算出榔桥岩体花岗闪长岩“锆石饱和温度”为749～781℃，脉岩花岗斑岩“锆石饱和温度”为722～745℃，指示岩浆在成岩过程中快速冷却；元素地球化学研究显示，本区岩石在成岩过程中发生斜长石、钾长石以及副矿物磷灰石、钛铁矿的分离结晶作用。锆石Ce（Ⅳ）/Ce（Ⅲ）比值计算表明榔桥岩体成岩过程中的高氧逸度有利于该区域发生Cu-Au矿化，而斜长石的分离结晶使得EuN/EuN*比值降低，为0．2～0．4。榔桥岩体具有富集大离子亲石元素以及Pb，亏损高场强元素（Nb、Ta、Zr，Ti），以及轻重稀土发生明显的分异，轻稀土相对重稀土明显富集的特征，与岛弧岩浆岩类似；大地构造背景判别表明该岩体的形成与古太平洋板块对欧亚大陆的俯冲碰撞作用密切相关。
안휘경현랑교화강섬장암체위분포우환남태습대북연각만동용형복식암체。해암체주침입기량개화강섬장암양품화침입후기맥암일개화강반암양품적고석 U-Pb 년령분별위135．6±1．8Ma，137．6±2．0Ma，136．4±1．9Ma，현시암체형성우조백성세。고석 Hf동위소분석표명랑교암체가능유중원고대지각물질부분용융형성，동시혼염유소량고원고대지각물질。근거전암Zr함량계산출랑교암체화강섬장암“고석포화온도”위749～781℃，맥암화강반암“고석포화온도”위722～745℃，지시암장재성암과정중쾌속냉각；원소지구화학연구현시，본구암석재성암과정중발생사장석、갑장석이급부광물린회석、태철광적분리결정작용。고석Ce（Ⅳ）/Ce（Ⅲ）비치계산표명랑교암체성암과정중적고양일도유리우해구역발생Cu-Au광화，이사장석적분리결정사득EuN/EuN*비치강저，위0．2～0．4。랑교암체구유부집대리자친석원소이급Pb，우손고장강원소（Nb、Ta、Zr，Ti），이급경중희토발생명현적분이，경희토상대중희토명현부집적특정，여도호암장암유사；대지구조배경판별표명해암체적형성여고태평양판괴대구아대륙적부충팽당작용밀절상관。
The Langqiao granodiorite intrusion is a complex pluton with melted crust-mantle materials,located in the northern margin of the fold belt in Jingxian county of South Anhui province.The U-Pb dating results for zircons from two granodiorite samples formed in main forming stage of the Langqiao intrusion and one porphyry granite samples from the vein rock formed at the later forming stage yielded weight average ages of 135. 6±1. 8Ma,137. 6 ±2. 0Ma,136. 4 ±1. 9Ma,respectively,indicating the intrusion formed in the Early Cretaceous.The zircon Hf isotopic analysis suggested that this intrusion was formed by partial melting of Mesoproterozoic crustal materials,contaminated by a small amount of Paleo-proterozoic crutal materials.The “zircon saturation temperature”calculated by whole-rock Zr contents show the magmatic crystallization temperature of Langqiao granodiorite intrusion and porphyry granite from vein rock is 749~781℃,722~745℃,respectively,indicating rapid cooling history of magma;the element geochemical studies show that the intrusion formed accompanied with fractional crystallization of plagioclase, K-feldspar and the accessory minerals,such as apatite,ilmenite.Zircon Ce(Ⅳ)/Ce(Ⅲ)ratios suggest the high oxygen fugacity in the magmatic process is conducive the Cu-Au mineralization,while the fractional crystallization of plagioclase reduced EuN/EuN* to 0. 2~0. 4 .The Langqiao intrusion is enriched in large-ion lithophile elements,Pb,depleted in high field strength elements (Nb,Ta,Zr,Ti),also has obvious differentiation between LREE and HREE,with more enriched LREE than HREE,similar to the arc magmatic rock;tectonic setting discrimination diagrams suggested the formation of Langqiao intrusion was closely related to the subduction and collision of the Paleo-pacific plate towards the Euroasian continent.