造山带隆起剥蚀过程与沉积记录

大别山造山带是中生代碰撞造山作用的产物，其隆起过程中形成了合肥盆地。本文对合肥盆地侏罗系碎屑岩进行了成分分析，发现砾岩中有两类榴辉岩，一类为高压变质榴辉岩，另一类为超高压变质榴辉岩。对砂岩中碎屑白云母的成分分析表明，指示高压变质作用的多硅白云母在较低层位已大量出现。重建的碎屑物注入顺序为：非超高压变质岩一高压变质岩一超高压变质岩。结合变质岩石学研究和地球物理观测资料重建的大别山造山带内部结构，可进一步重建大别山的剥蚀历史：大别山造山带最先（三尖铺组沉积初期）受到剥蚀的是非超高压变质的片岩、片麻岩及大理岩，高压变质岩折返到地表受到剥蚀不晚于中侏罗世初期（三尖铺组沉积早期），而超高压变质岩折返到地表经受剥蚀的时问稍早于中侏罗世中期（凤凰台组沉积初期）。天山是典型的陆内造山带，其隆起是新生代以来印度板块与欧亚板块碰撞的一种远程效应。本文对天山发育的花岗岩磷灰石裂变径迹分析，并对南侧的塔里木盆地北部古近系及新近系沉积岩进行了碎屑岩物源分析，在新的磁性地层学格架中讨论了天山的隆起剥蚀历史。砾石组分的突然变化发生在75-35Ma，26-17Ma和12-8Ma间，从中天山物源区逐渐变为南天山物源区，12Ma后变为以南天山为主要物源区。砂岩及重矿物组分变化表明，物源在124Ma、26（-24）Ma及15（-12）Ma时发生过变化。磷灰石裂变径迹则进一步揭示了天山的3阶段差异性隆起历史：天山的早期隆起发生在124-80Ma间，从中天山和南天山的交界处开始并向南扩展；第二次隆起发生在大约100-60Ma间，从中天山开始向南扩展；第三次隆起从大约50Ma开始，并向北南两侧扩展，至大约30Ma时扩展到北天山，约20Ma时扩展至南天山；其后，南天山在15（-12）Ma时发生了独立的隆起事件。本文的两个研究实例表明，盆地的充填符合计算机数据结构的堆栈过程，但造山带的隆起剥蚀却会出现明显的差异性。不能简单地说造山带的剥蚀和盆地的充填具镜像对称关系，这有可能导致错误的认识，一定要具体事例具体分析。

山西省保德—兴县铝土矿成矿区带划分及含矿岩系特征

山西省保德—兴县铝土矿区位于华北陆块吕梁山中段西缘,山西断隆吕梁—太行块隆西侧,鄂尔多斯台坳河东拗陷东缘中北部,鄂尔多斯盆地和吕梁造山隆起带的结合部位,为河东铝土矿集区的重要组成部分,是有利的铝土矿成矿区域。依据山西省中生代构造单元及铝土矿成矿区带划分方案,矿区分别位于鄂尔多斯东缘保德—临县南北向块凹构造单元及河东赋矿带中部河曲—保德—兴县—临县成矿区带内。受古地形及多期构造运动的影响,铝土矿普遍含铁较高,粘土岩层多直接覆盖于奥陶系不整合面之上,耐火粘土矿多缺失,山西式铁矿也不发育,见有铁矾土。

The thermal history and uplift process of the Ouxidaban pluton in the South Tianshan orogen:Evidence from Ar-Ar and(U-Th)/He

The uplift and exhumation process in the Tianshan orogen since the late Paleozoic were likely related to the preservation of ore deposits. This study involved reconstructing the whole tectonic thermal history of the Ouxidaban pluton in central South Tianshan Mountains based on hornblende/plagioclase Ar-Ar and zircon/apatite （U-Th）/He methods. The thermal history and uplift process of central South Tianshan Mountains since the late Paleozoic were analyzed according to the results of previous works and cooling/exhumation rate features. The hornblende yields a plateau age of 382.6_＋3.6 Ma, and the plagio- clase yields a weighted mean age of 265.8_＋4.9 Ma. The Ouxidaban pluton yields weighted mean zircon （U-Th）/He age of 185.8±4.3 Ma and apatite （U-Th）/He age of 31.1±2.9 Ma, respectively. Five stages of tectonic thermal history of South Tianshan Mountains since the late Paleozoic could be discriminated by the cooling curve and modeling simulation： （1） from the latest Silurian to Late Devonian, the average cooling rate of the Ouxidaban pluton was 7.84℃/Ma; （2） from the Late De- vonian to the latest Middle Permian, the average cooling rate was about 2.07℃/Ma; （3） from the latest Middle Permian to the middle Eocene, the cooling rate decreased to about 0.68℃/Ma, suggesting that the tectonic activity was gentle at this time; （4） a sudden increase of the cooling rate （5.00℃/Ma） and the exhumation rate （0.17 mrn/a）, and crustal exhumation of -1.83 km indicated that the Ouxidaban pluton would suffer a rapid uplift event during the Eocene （-46-35 Ma）; （5） since the middle Eocene, the rapid uplift was sustained, and the average cooling rate since then has been 1.14℃/Ma with an exhumation rate of about 0.04 mm/a and an exhumation thickness of 1.33 km. The strong uplift since the Cenozoic would be related to a far-field effect from the Indian and Eurasian plates＇ collision. However, it was hysteretic that the remote effect was observed in the Tianshan orogenic belt.