苏鲁超高压带北部中生代岩浆侵入活动与同碰撞—碰撞后构造过程:锆石 U-Pb 年代学  

Evolution of syn-to post-collisional magmatism from north Sulu UHP belt,eastern China:zircon U-Pb geochronology.

作　　者：郭敬辉[1] 陈福坤[1] 张晓曼[1] Siebel W 翟明国[1] 

机构地区：[1]中国科学院地质与地球物理研究所岩石圈演化国家重点实验室,北京10029 [2]德国蒂宾根大学地球化学研究所,蒂宾根72074

出　　处：《岩石学报》2005年第4期1281-1301,共21页Acta Petrologica Sinica

基　　金：国家重点基础研究发展规划项目(G1999075502);中国科学院重大创新项目(KZCX1-07)

摘　　要：苏鲁超高压变质带北部威海地区发育大量中生代侵入体。本文报道了新的同位素稀释法和 SHRIMP 锆石 U-Pb 同位素年龄数据,确认该区中生代侵入岩浆活动主要有三期,分别是三叠纪晚期～210Ma,侏罗纪晚期160～140Ma 和白垩纪早期～110Ma。三叠纪晚期主要是橄榄安粗岩系列的侵入体,包括邢家碱性辉长岩(211±5Ma 和213±5Ma),甲子山辉石正长岩(211.9±1.5Ma 和209.0±6.5Ma),槎山正长花岗岩(205.7±1.4Ma),它们的形成可能指示深俯冲大陆的板片断离作用。侏罗纪晚期主要有垛崮山花岗闪长岩体(161±1Ma),文登花岗岩体(160±3Ma)和昆嵛山花岗岩体(142±3Ma)。大量700～800Ma 的继承锆石指示这些花岗岩是俯冲的扬子板块部分熔融的产物,它们可能起因于碰撞加厚地壳的拆沉作用。白垩纪早期的侵入体代表性的有六度寺辉石闪长岩(114.5±0.8Ma),秦薄顶钾长巨斑状花岗岩(114±1Ma),三佛山钾长斑状花岗岩(113±1Ma)和伟德山花岗岩(108±2Ma)。这些高钾钙碱系列侵入体,是中国东部普遍发育的岩石圈减薄过程中强烈的壳幔相互作用的产物。Numerous Mesozoic plutons are exposed within the ultrahigh-pressure （UHP） metamorphic terranes in the Weihai area of the northern SuLu UHP belt. They occur as multi-pulse intrusive complexes or small size stocks of diversity rock types including shoshonitic gabbros and syenites, S-type granites, and Ⅰ-type granites of high K alkaline series. A temporal evolution has be established on the basis of precise zircon U-Pb ages by single grain isotope dilution method and SHRIMP technique and petrochemical investigations. （1） Shoshonitic magmatism commenced 20Ma after UHP metamorphism in the late Triassic. Typical plutons of shoshonitic series represented by Xingjia alkali gabbros （ 211± 5 Ma and 213 ± 5 Ma） , Jiazishan pyroxene syenite （ 211.9 ± 1.5 Ma and 209.0 ± 6.5Ma ） and Chashan syenogranite （205.7± 1.4Ma）. They derived from enriched mantle contaminated by subducted continental crust, and were likely the response to mantle upwelling induced by slab breakoff after continental subduction. （2） Jurassic calc-alkaline intrusions postdated the UHP metamorphism by 60 -80Ma. The Duogushan granodiorite （ 161 ± 1Ma）, the Wendeng monzogranite （ 160 ± 3Ma） and the Kunyushan monzogranite and garnet-bearing leucogranite （ 142 ± 3Ma） are representative plutons. These granites contain most inherited zircons of 700 -800Ma suggesting that they were melting products of the South China Block. They were likely to be originated from crustal melting induced by lower crustal delamination after the Triassic UHP collision. （3） The final magma pulse appeared in early Cretaceous at -110Ma, represented by the Liudusi pyroxene diorite （114.5 ±0.8Ma）, Taiboding Kf-porphyritic granite （ 114 ± 1Ma）, Sanfoshan Kf-porphyritic granite （ 113 ± 1Ma） and Weideshan granite （ 108± 2Ma） and numerous small intrusions. They show characteristics of the high-K calc-alkaline and shoshonitic series. These granites are ascribed to strongly crust-mantle interaction during Cretaceous mantle upwel

关 键 词：花岗岩 碱性岩 碰撞后 苏鲁超高压带 胶东 

分 类 号：P588.348[天文地球—岩石学] P597.3[天文地球—地质学]