【摘要】 蚌埠隆起位于华北克拉通南部,胶辽吉造山带的南端,主要由凤阳群和五河杂岩构成。五河杂岩的研究主要集中于年代学以及地球化学领域,其变质P-T条件和地层剖面等研究相对较弱。本文试图从变质岩石学、构造地质学和锆石年代学角度构建朱顶—石门山一线的地壳剖面。通过大量的P-T条件评价,确定了朱顶单元、庄子里单元和石门山单元之间的区别和界限,其中朱顶单元温压结果为低压麻粒岩相:T=720℃~840℃,P=0.90~1.33 GPa;庄子里单元温压结果同为低压麻粒岩相,但温度和压力均低于前者:T=700℃~820℃,P=0.50~0.90GPa;石门山单元因岩性限制,仅用白云母Ti温度计拟合计算,结果为低压角闪岩相:T=610℃~700℃,P=0.30~0.50 GPa。锆石U-Pb定年获得的变质年龄为2 413±22Ma,与前人研究结果基本一致。此外,庄子里地区岩体和磨盘山岩体的锆石U-Pb年龄晚于2.5~2.4 Ga,因此应属于后期侵入岩,计算剖面厚度时要考虑岩体厚度的影响。研究区的岩层产状在45°~60°之间,按照两个极端值计算(不考虑岩体厚度)时获得地壳总厚度为16 km,结合3条糜棱岩带的存在,其应属于中-上地壳的物质组成部分。朱顶—石门山一线的地壳剖面,自南向北,以白石山和磨盘山岩体为界,依次为上地壳、中-上地壳和下地壳,温压条件自南向北呈递增趋势。更多还原

【Abstract】 Bengbu uplift located at the south of north craton and existed in south part of Jiao-Liao-Ji orogenic zone,it consist of Fengyang unit and Wuhe unit.Previous studies of Wuhe diamictite mainly direct to chronology and geochemistry,so it metamorphism P-T conditions and stratum profile has rarely attention.The contribution try to build Zhuding-Shimenshan lithosphere profile base on the study of metamorphic petrology,tectonic geology and zircon U-Pb chronology.Conducted large amount of P-T condition calculation we had been confirmed the ambit and the difference among Zhuding unit,Zhungzili unit and Shimenshan unit.The results of Zhuding unit is LGR and its P-T conditions are as follows:T = 720 ℃ ~ 840 ℃,P = 0.90 ~ 1.33 GPa.Zhuangzili unit’s results similar to former:T = 700 ℃ ~ 820 ℃,P = 0.50 ~ 0.90 GPa.The last unit limited by the lithology we just did the P-T conditions calculation with Ti-in-muscovite geothermometer,and the data shows it might be AM facies:T = 610 ℃ ~ 700 ℃,P = 0.30 ~0.50 GPa.Furthermore,we had attained the zircon U-Pb average age of ZK1013H19 is 2 413±22 Ma,and it in accord with predecessors studies.Moreover,because of the zircon U-Pb of Mopanshan and Nvshan plutons are later than 2.5 ~ 2.4 Ga,they are intrusive rock,so we should take it into consideration when we calculated.And,the attitude of stratum is between45° and 60°,using two of the extreme stratum to calculate,the thickness of lithosphere is about16 km.And,taking account of three mylonite belts,we reckon Zhuding-Shimenshan belts belong to mid-upper crust.Summarized the P-T conditions,tectonic geology and zircon U-Pb chronology,the paper built the thinlithosphere profile preliminary.All the results suggest that from south to north are Zhuding unit,Zhuangzili unit and Shimenshan unit,the ambit is Baishishan and Shimoshan pluton respectively.And the P-T conditions show an increasing trend from south to north in Zhuding-Shimenshan belt.更多还原