【作者】 续海金；

【导师】 马昌前；

【作者基本信息】 中国地质大学 ， 岩石学， 2005， 博士

【摘要】 大别造山带不仅是世界上最大的超高压变质岩区，而且也是陆—陆碰撞造山作用结束之后岩浆活动最为强烈的地区。大量年代学研究表明，大别造山带大规模的岩浆活动主要发生在120—140Ma。本文以大别造山带核部晚中生代侵入岩为主要对象，瞄准“中国东部中生代大规模岩浆作用与深部过程”等大陆动力学的关键科学问题开展研究。通过对大别山核部晚中生代侵入岩的侵位序列、形成时代和成因的研究，探讨大别造山带晚中生代地质演化和大陆动力学过程，获得如下重要认识： 1．野外地质研究。(1) 大别山核部晚中生代岩浆侵位次序由早到晚为，镁铁质—超镁铁质岩块→片麻状石英二长闪长岩→斑状或眼球状二长花岗岩(主体)→细粒二长花岗岩→酸性岩脉(碱长花岗(斑)岩：钾长伟晶岩→石英正长(斑)岩)→中—基性岩脉。(2) 镁铁质—超镁铁质岩块与片麻状石英二长闪长岩和斑状或眼球状二长花岗岩，在空间上紧密共生，片麻状石英二长闪长岩和斑状或眼球状二长花岗岩呈“网格状”侵入或包裹镁铁质—超镁铁质岩块。(3) 走向为NE的正断层错断晚期酸性和基性岩脉，表明岩浆活动结束之后，大别山核部又发生了一次NW-SE向的脆性伸展的构造事件。(4) 石鼓尖片麻状石英二长闪长岩的片麻理走向为NNE向，与全区NE向和NNE向的走滑型韧性剪切带一致，而天堂寨等斑状或眼球状二长花岗岩局部有弱的片麻理，说明在石鼓尖岩体侵位之后和天堂寨等斑状或眼球状二长花岗岩体侵位之前或同时，存在一次NE向的韧性剪切走滑的构造事件，可能受郯庐断裂大规模平移走滑的影响。2．岩相学特征。由早到晚，从岩体到岩脉，岩相学特征具有明显的变化规律。(1) 岩体，石鼓尖片麻状石英二长闪长岩，片麻状构造，主要矿物组成为斜长石(30～35％)、钾长石(20～25％)、角闪石(20～25％)和石英(10～15％)；天堂寨等斑状或眼球状二长花岗岩，似斑状或眼球状结构，主要矿物组成为斜长石(35～40％)、钾长石(25～30％)和石英(20～30％)；吴家山和薄刀峰细粒二长花岗岩，细粒结构，主要矿物组成为斜长石(35～40％)、钾长石(～30％)和石英(25～30％)。岩石中石英和钾长石的含量升高，反映岩体的侵位深度变浅，与大别造山带全区晚中生代花岗岩类的变化特征相吻合。(2) 岩脉，酸性岩脉为碱长花岗岩和碱长花岗斑岩；中性岩脉主要为闪长岩和闪长玢岩；基性主要为煌斑岩类和辉长岩，其次是辉绿岩和辉绿玢岩。反映由壳源向幔源的演化过程和地壳强烈伸展的构造体制，因为碱长花岗(斑)岩和煌斑岩是伸展减薄的构造体制的标志；(3) 从岩体到岩脉，反映地壳伸展减薄的演化过程，以及岩浆侵位依次变浅更多还原

【Abstract】 The Dabie orogenic belt and the Su-lu region in central china are known to contain the largest distribution of ultrahigh pressure metamorphic rocks in the world, but also known to appear the strongest magmatism after ending of curst-crust collision. Abundant geochronology data show that the large-scale postcollisional magmatism is from 120 to 140 Ma in age. The main objects of this study are the late Mesozoic (Cretaceous) magmatic intrusions in the central of Dabie orogenic belt, aiming at the key scientific questions of the continental dynamics such as the relationship between the Mesozoic large-scale magmatism and the deep processes in East China. The purposes of this paper are: (1) to present intrusive sequences through field relationships, (2) to present new age information for magmatic intrusions using single zircon SHRIMP U-Pb dating, (3) to use geochemical and Sr-Nd isotope tracers associating with precise age data to constraint petrogenetic processes of these late Mesozoic rocks, and (4) to discuss geological evolution and continental dynamics processes for the Dabie collisional orogen in late Mesozoic.1. Field relationships. (1) The late Mesozoic magmatic intrusion sequences in the central of the Dabie orogenic belt from early to late are from mafic-ultramafic rocks, to gneissic quartz monzodiorite, which is found to be the earliest granodiorite in late Mesozoic by now, to porphyritic or augen monzogranites, which are the main body of the late Mesozoic huge magmatism in the Dabie orogenic belt, to fine monzogranites, to acidic (felsic) dykes including from K-feldspar pegmatite to alkali feldspar granite or granite-porphyry, and to dark dykes. The dark dykes are neutral dykes and basic dykes not to be distinguished in the field. (2) Mafic-ultramafic rocks are intimate intergrowth with gneissic quartz monzodiorite and porphyritic or augen monzogranites in the space. (3) The NE strike normal fault cut off acidic and basic dykes that implicate where there takes place a NW-SE brittle extensional tectonics after magmatism ending in the Dabie orogen. (4) The gneissic strike of Shigujian gneissic quartz monzodiorite is NE and NNE, which is consistent with ductile shear belt that parallel Tan-Lu fault. Tiantangzhai etc porphyritic or augen monzogranite have a local weekly gneissosity. It’s obvious that there exist a tectonic event after emplacement of Shigujian pluton and before or at更多还原