New Data on the Mineralogy of Chromite from the Nuggihalli Schist Belt, Western Dharwar Craton, Karnataka, India:Petrogenetic Implications

The occurrence of rhythmic layering of chromite and host serpentinites in the deformed layered igneous complexes has been noticed in the Nuggihalli schist belt (NSB) in the western Dharwar craton, Karnataka, South India. For this study, the chromitite rock samples were collected from Jambur, Tagadur, Bhakatarhalli, Ranganbetta and Byrapur in the NSB. Petrography and ore microscopic studies on chromite show intense cataclasis and alteration to ferritchromite. The ferritchromite compositions are characterized by higher Cr number (Cr/[Cr+Al]> (0.68-0.98) and lower Mg number (Mg/[Mg+Fe]) (0.33-0.82) ratios in ferritchromite compared to that of parent chromite. The formation process for the ferritchromite is thought to be related to the exchange of Mg, Al, Cr, and Fe between the chromite, surrounding silicates (serpentines, chlorites), and fluid during serpentinization.     

华北某地发现皂石矿

皂石是蒙皂石家族的重要成员,工业应用性能优越,资源相对稀少,矿石经济价值较高。作者在华北地台北缘的侏罗纪火山岩地层中发现一种矿石,经检测证实属皂石。     

岩石圈减薄与成矿关系的不均一性

结合实际工作中的体会,提出和讨论了“岩石圈减薄与成矿关系的不均一性”这一有意义的科学问题。岩石圈减薄导致岩石圈中分布不均一的金、钼、钨等成矿元素被消耗带出至地壳中成矿,是中国东部金、钼、钨大规模成矿的基本机制;华北地块岩石圈减薄对金、钼、钨大规模成矿的贡献时限始自构造转折开始时而终至岩浆富集地幔源向亏损地幔源转化期,即可能在163～136Ma至117～80Ma期间;岩石圈在时间和空间上的不均一减薄可能是地壳中不同类型的金、钼、钨等矿床和矿集区时空分布差异性的重要原因。     

塔里木克拉通盆地油气勘探对策

塔里木克拉通盆地包括整个盆地“三隆四坳”^[1]中的塔北隆起、北部坳陷、塔中隆起、巴楚隆起等主要构造单元（见图1）。经多年勘探,目前已探明和发现了众多油气田（藏）：塔北隆起上的轮南、塔河、东河塘等油田,塔中隆起上的塔中4、塔中16油田,巴楚隆起上的和田河气田、巴什托甫油田,北部坳陷中的哈得逊油田等。这些海相成因的油气主要富集在奥陶系碳酸盐岩与石炭系、三叠系、侏罗系砂岩储集层中,来源于寒武系和中上奥陶统两套烃源岩。     

内蒙古呼伦贝尔早中生代花岗岩的年代学和岩石地球化学研究：对岩石成因和地球动力学机制的制约

微细粒钛铁矿的回收制约着我国攀西地区钛资源的高效开发利用。四川某矿业公司的斜板溢流原矿属辉石、橄榄石混合型钛铁矿,且粒度极细,-19 μm产率为79.22％,其中TiO2分布率为87.54％。研究结果表明,预先采用强磁选可有效消除部分超微细粒钛辉石、橄榄石等易浮杂质对浮选分离的不利影响,磁选精矿通过一次粗选五次精选一次精扫选流程,可获得钛精矿产率为21.85％,TiO2品位为47.44％,回收率为62.89％的良好指标,为矿山高效利用钛资源提供了合理的技术方案。     

塔里木盆地西部及邻区板块构造属性与区划

根据蛇绿岩带分持征及配套系的研究，在研究区内划分出了五条蛇绿岩带。以塔里木北缘蛇绿岩带为界将塔里木陆块与哈萨克斯坦板分开；以多期俯冲形成的康西瓦蛇绿岩带将塔里木陆块与高加索－羌塘板块分开。     

白音哈尔金矿床成矿作用

白音哈尔金矿床是华北克拉通北缘多金属成矿带中典型的石英脉一破碎蚀变岩复合型金矿床。通过野外精细地质填图、矿区构造测量、及Au、As、鲰、cu、Pb、zn和Bi等元素地球化学特征分析,认为白音哈尔金矿床是分布受断裂构造控制的与中酸性岩体有关的多期次热液叠加成矿作用形成的石英脉一破碎蚀变岩复合型金矿床;石英脉型矿体中金等成矿物质主要来自中、上元古界温都尔庙群和白乃庙组中的绿片岩一角闪岩相的古老地层,蚀变岩型矿体中的金等成矿物质主要来自华力西晚期的石英闪长岩和斜长花岗岩体。对认识多期次、不同成矿作用叠加的成矿规律具有一定的理论与实践指导意义。     

喜马拉雅运动在新疆中、新生代盆地形成中的作用

分析了中国新疆维吾 自治区境内沉积盖层中的不整合及不同时代形变的区域性分布特征,并评价了喜马拉雅造山运动对新疆现今构造的影响。指出,塔里木盆地（地台）在晚第三纪和喜马拉雅运动期就成为新疆主要的油气生成区。塔里木盆地仅受到了谐振运动的影响,这种谐振运动与四周活动区的构造活动有关（使塔里木克拉通盖层的同沉积构造及岩相带复杂化）,但这种谐振运动在靠近褶带的范围内也未能形成褶皱山。只是新生代晚期的形变作用     

Late Mesozoic extensional tectonics of the Liaodong Peninsula massif:Response of crust to continental lithosphere destruction of the North China Craton

Unlike most Precambrian cratons that have thick sub-continental lithospheric roots,the Archean lithosphere beneath the North China Craton is thin (reduced from 200 km to about 80 km),and has been replaced by a geochemically juvenile lithospheric mantle.This is a unique regional geological event,which has attracted worldwide attention.In the North China Block,Late Mesozoic extensional tectonics is evident by low-angle detachment faults,syntectonic plutons bounded by ductile faults,metamorphic core complexes ...     

Mesozoic contraction deformation in the Yanshan and northern Taihang mountains and its implications to the destruction of the North China Craton

Mesozoic contraction deformation in the Yanshan and Taihang mountains is characterized by basement-involved thrust tectonics,basement-cored buckling anticlines and ductile thrust and nappe tectonics.Most of these deformations are orientated west-east,west-northwest and northeast to north-northeast.The contraction deformations began in the Permian,continued through the Triassic and Jurassic and terminated in the Early Cretaceous,and constitute an important part of the destruction of the North China Craton.It...