Provenance analysis of Cenozoic conglomerates: Insights from Lower Cretaceous radiolarians in chert clasts from the Xigaze area,southern Tibet

Conglomerates, exposed on either side of the Yarlung Tsangpo suture zone (YTSZ) in southern Tibet, have attracted wide attention in elucidating uplift and erosion histories of the Himalayan-Tibetan orogen. However, the provenance of these conglomerates remains controversial. Although radiolarian-bearing chert clasts within these conglomerates have received little focus, identification of the radiolarian assemblages they contain could shed light on the provenance of these sedimentary units. We present the first report of Upper Jurassic to Lower Cretaceous (upper Kimmeridgian–lower Barremian) radiolarian assemblages recovered from chert clasts within the Liuqu and Gangrinboche conglomerates in the Xigaze area. To extract radiolarian fossils from independent clasts in the conglomerates, a detailed and efficient experimental process is illustrated. The assemblages are well correlated to those in the YTSZ and Tethyan Himalaya, showing typical Tethyan characteristics. The lithology of chert clasts and ages of constituent radiolarian faunas suggest that the chert clasts in Liuqu and Gangrinboche conglomerates were derived from the Bainang terrane. This interpretation implies that Early Cretaceous accretionary complexes in the YTSZ had been exposed and eroded before deposited as clasts in the Cenozoic Liuqu and Gangrinboche conglomerates.     

中国西藏发现类三角蚌类祖先闯入非海相领域的证据（英文）北大核心CSCD

新发现的双壳类化石命名为Baxoitrigonia baxoiensis gen. et sp. nov.,产地为藏东八宿林卡家东,化石产于景星动物群之下的拉贡塘组下段,同层位有菊石和其他海相双壳类,时代为晚侏罗世Tithonian期;化石的外部特征很接近于三角蛤类Iotrigonia属,但前闭肌痕特征又相似于类三角蚌类,被认为是三角蛤类闯入非海相领域后演变成类三角蚌类的产物。此发现提供了生物和地层两方面的直接证据,证明非海相类三角蚌类(Trigonioidoidea超科)起源于海相三角蛤类(Trigoniida目),而不是起源于珠蚌类(Unionida目)。海相三角蛤类闯入边缘隔绝的洛隆-八宿地区并演变为非海相类三角蚌类,是一次典型的边域成种事件。     

西藏草原5种主要有毒植物营养成分

采用国家标准法对西藏天然草原茎直黄芪(Astragalus strictus)、甘肃棘豆(Oxytropis kansuensis)、毛瓣棘豆(Oxytropis sericopetala)、瑞香狼毒(Stellera chamaejasme)和藏橐吾(Ligularia rumicifolia)5种主要有毒植物不同物候期常规营养成分和矿质元素含量进行测定。结果显示,在5种植物中,粗蛋白平均含量以茎直黄芪最高,其次为甘肃棘豆,且两者粗蛋白含量均超过19%;茎直黄芪中花期粗蛋白含量最高,花前期最低,花期和花果期差异不显著(P0.05);而甘肃棘豆中粗蛋白含量以花前期最高,花果期最低,花前期和花期差异不显著。粗纤维平均含量由高到低依次为毛瓣棘豆、藏橐吾、茎直黄芪、甘肃棘豆和瑞香狼毒,且均以花果期最高,花前期最低。5种植物Mg、Fe、Cu、Mn和Zn含量均以花前期最高,花期次之,花果期最低;但Se含量花果期相对较高。由此得出,茎直黄芪和甘肃棘豆营养较为丰富,具有潜在饲用价值,毛瓣棘豆、瑞香狼毒和藏橐吾营养价值偏低。     

川藏铁路某隧道不明气体成因机制研究

为解决复杂地质条件地区隧道工程建设中出现的不明气体问题,以川藏铁路某隧道出现不明气体为切入点,结合工程地质学、地球化学等学科交叉的研究方法与思路,对该不明气体的成因机制及演化特征进行研究,探索一种研究不明气体的新思路。基于现场采样测试与全天候监测,总结分析该不明气体成分特征及其演化规律,得出该不明气体为混合成因气体;同时,从不明气体的工程地质条件入手,着眼于区域油气资源和煤系地层的分布及区域地质构造、岩石裂隙发育情况,排除不明气体由其他地区运移而来的可能;在此基础上,进行岩石室内试验,通过对不明气体赋存环境进行地球化学分析,分别论证气体的有机成因及无机成因,得出该不明气体是原地产生的,经历了有机成因和无机成因2个阶段且储量有限,对工程后期影响不大,为隧道后期顺利施工提供了指导。     

From the “Good Tradition” to Religion on Some Basic Aspects of Religious Conversion in Early Medieval Tibet and the Comparative Central Eurasian Context

What Western academic literature described as ethnic or cultural Tibet in fact implies something composite and processually constructed: Tibet then often appears as a typical example for explanations of collective identity (and ethnicity). Such approaches increasingly are applied in present-day anthropology and historical studies, highlighting the historical conditions and the politically, socially and ideationally constructed features of identity. In Tibet, identity-building was strongly related to the spread of Buddhism. The new religion was introduced in the time of the Tibetan Empire (seventh to ninth century), but it was only its later spread (from the eleventh century) that led to the effective, all-embracing establishment of Buddhism in the Highlands. It was interlinked with regionally different forms of political manifestations—the founding of Buddhist kingdoms at the periphery and the emergence of monastic hegemonies in the central regions. These developments correlated with processes of conversion, which in its narrative model is described as an act of conquest, taming and civilizing the physical universe and which in theory actually never ends. Apart from considering current anthropological discussions of the phenomenon of religious conversion, this paper will include a comparative view of the history of Christianization in early medieval Europe (especially in Western Europe—the Frankish kingdom and the barbarian zones North of the Rhine and the Danube, fifth to tenth century). Inter alia this also raises questions about the initial social forces and interests promoting the new religion's adoption, and to what extent formal similarities with the Tibetan case are ascertainable in Europe.     

基于中、高分辨率遥感数据的铜多金属矿化信息提取与找矿预测——以西藏别若则错地区为例

基于中、高分辨率遥感数据,对西藏别若则错地区开展了蚀变信息提取与找矿预测。首先利用ASTER中等分辨率遥感数据,快速获取成矿地质背景信息及遥感蚀变信息,优选找矿有利区。其次利用World View-2高分辨率遥感数据开展找矿有利区的岩性构造解译,重点解译中酸性侵入岩体、火山机构、断裂、地层岩性等控矿要素。最后在野外查证成果基础上,圈定了3处找矿靶区,取得了良好的应用效果。     

西藏玛那国地区遥感找矿预测

西藏玛那国地区处于班公湖—怒江成矿带西段,成矿层位为上白垩统竟柱山组砂岩。利用World View-2高分辨率遥感数据在玛那国地区开展1∶1万岩性—构造解译,重点进行了成矿层位的追索解译,结合Aster数据提取的遥感蚀变异常信息,野外查证发现玛那国地区存在铜、铁两种矿化。综合分析玛那国地区的矿化特征、成矿地质条件和控矿因素,建立了找矿标志,圈定铜银矿、铁金矿的找矿有利地段,为玛那国地区进一步的找矿工作提供了线索。     

西藏天然林资源保护工程现状及发展对策研究

1　天然林保护工程实施以来取得了明显的阶段性成果西藏是我国重要国有天然林区之一 ,现有有林地面积 75 1万hm2 ,约占国有林区天然林面积的 2 7 8% ,活立木蓄积量为 2 0 84亿m3 ,约占国有林区天然林蓄积量的 72 %。昌都地区的江达、贡觉、芒康 3县是我国长江流域的重要区域 ,     

西藏大冈底斯北部金属矿床成矿系列研究

依据近年西藏自治区矿产资源大调查的资料与西藏自治区矿产资源潜力评价研究获得的系统、详细的矿产资源资料,编写论述了西藏大冈底斯北部(包括班公湖-怒江成矿带、北冈底斯成矿带、中冈底斯成矿带三个成矿带)的矿产地质特征及成矿分布规律与成矿系列。班公湖-怒江成矿带包括燕山早期(洋盆形成时期,如东巧铬矿)及燕山中晚期(陆内俯冲挤压时期,如屋索拉金矿)岩浆作用有关矿床成矿系列和那曲-洛隆盆地与喜马拉雅期流体作用有关(如纳多弄铅矿)矿床成矿系列;北冈底斯成矿带矿床主要分布在申扎—嘉黎一线的北部地区(亦称冈底斯北矿带),包括玉古拉镍矿(燕山早期,岩浆岩型)、舍索铜矿(燕山中晚期,矽卡岩型为主)、尤卡朗-昂张铅矿(燕山中晚期,热液型为主)、俄龙呷砷矿(燕山晚期—喜马拉雅早期,流体-改造型为主)四个地区不同类型矿床成矿系列;中冈底斯成矿带包括近东西向两个成矿亚带,北边为革吉-雄巴-文部成矿亚带燕山中晚期(如尕尔铜金矿)及狮泉河-申扎弧-盆系演化期岩浆热液成矿作用的矿床成矿系列,南边为朗久-塔诺错-纳木错成矿亚带喜马拉雅中晚期(如甲岗钨钼铋矿)岩浆热液成矿作用的矿床成矿系列。     

藏南努日铜-钨-钼矿床晚白垩世石英闪长岩U-Pb定年及其地球化学特征

藏南努日矿床位于冈底斯成矿带南缘,前人获得的辉钼矿Re-Os同位素年龄为23 Ma,与明则和程巴矿床成矿时代一致,但矿区内至今未发现与矿化有关的成矿斑岩体。本文报道了努日矿区新发现的与矿化关系密切的石英闪长岩的地球化学特征,获得石英闪长岩的LA-ICP-MS锆石U-Pb年龄为93.42±0.76 Ma,与同一成矿带内桑布加拉和克鲁铜金矿成矿时代一致(90~93 Ma),表明矿区可能存在两期成矿事件。石英闪长玢岩的主量微量元素SiO_2含量为57.19%~58.23%,A1_2O_3含量为15.78%~16.03%,MgO含量为4.74%~5.32%,Mg~#指数为65.2~67.3;富集大离子亲石元素(Rb、Sr、Ba、U等)及轻稀土元素,亏损高场强元素,显示出埃达克岩特征。研究表明石英闪长玢岩形成于洋壳俯冲阶段的弧岩浆岩,洋壳熔融形成的母岩浆侵入近地表形成早期铜多金属矽卡岩矿化。晚白垩世成矿事件的发现进一步佐证了研究区存在两期矿化叠加事件,拓展了研究区找矿方向。