Relationship Between Himalayan Tectono-Magnetic Movement and Mineralization in Lanping Basin, Yunnan Province

RELATIONSHIP BETWEEN HIMALAYAN TECTONO-MAGNETIC MOVEMENT AND MINERALIZATION IN LANPING BASIN, YUNNAN PROVINCE     

GEOPHYSICS

正20141944Bao Hanyong(Research Institute of Exploration and Development,Jianghan Oilfield,SINOPEC,Wuhan 430223,China);Guo Zhanfeng Tectonic-Thermal Evolution of the Subei Basin since the Late Cretaceous(Geological Journal of China Universities,ISSN1006-7493,CN32-1440/P,19(4),     

Diversity, Distribution Pattern and Conservation Status of the Plants Used in Liver Diseases/Ailments in Indian Himalayan Region

Introduction The Indian Himalayan Region (IHR) is known for its unique, natural, representative biodiversity (Samant et al. 1998a). This biodiversity is being utilized by the inhabitants of the IHR in various forms, i.e., medicine, food (wild edibles), fuel, fodder, timber, making agricultural tools, fiber, religious and various other purposes (Samant and Dhar 1997, Samant et al. 1998b). In the remote areas of the IHR where primary health centers are located far from the villages, the in…     

Petrology of high-pressure granulites from the eastern Himalayan syntaxis

The eastern Himalayan syntaxis, situated at the eastern terminus of the Himalayas, is the least-known segment of the Himalayas. Recent research in this area has revealed that the syntaxis consists of the Gangdise, the Yarlung Zangbo, and the Himalayan units, each of which is bounded by faults. The Himalayan unit, the northernmost exposed part of the Indian plate, mainly contains amphibolite facies rocks, marked by the assemblages staurolite+kyanite+plagioclase+biotite+muscovite±sillimanite and garnet+amphibole+plagioclase, in the south; to the north, low- to medium-pressure granulite grade pelitic gneisses and marbles are present and are characterized by the assemblages garnet+sillimanite+K-feldspar+plagioclase or antiperthite+biotite+quartz±spinel±cordierite±orthopyroxene in gneisses, and anorthite+diopside±wollastonite and plagioclase+diopside+quartz+phlogopite+calcite in marbles. Within this unit, the Namula thrust system is a series of moderately north-dipping structures that displaced the granulite facies rocks southwards over the amphibolite facies rocks. High-pressure granulites occur as relics within these granulite facies rocks and contain garnet–kyanite granulite and garnet clinopyroxenite. The peak assemblage of the garnet–kyanite granulite includes garnet (core part)+kyanite+ternary feldspar+quartz+rutile. Sillimanite+garnet (rim part)+K-feldspar+ oligoclase+ilmenite+biotite and spinel+albite+biotite or spinel+cordierite±orthopyroxene, which are coronas around sillimanite and garnet, are retrograde products of this peak assemblage. Another peak assemblage includes very-high-Ca garnet (CaO 32–34 wt%, Alm₁₀±Grs_>80) and diopside (CaO 22–24 wt%), scapolite, meionite, quartz, and accessory Al-bearing titanite (Al₂O₃ 4–4.5 wt%). The diopside has kink bands. Partial or complete breakdown of Ca-rich garnet during post-peak metamorphism produced pseudomorphs and coronas consisting of fine-grained symplectic intergrowths of hedenbergite and anorthite. Thermobarometric estimates in combination with reaction textures, mineral compositions, and recent experimental studies indicate that these peak assemblages were formed at P=c. 1.7–1.8 GPa, T =c. 890 °C, and the retrograde assemblages experienced near-isothermal decompression to P=0.5±0.1 GPa, T =850±50 °C. The whole-rock compositions indicate that marble and pelite are plausible candidates for the protoliths. These facts suggest the following (1) sedimentary rocks were transported to upper-mantle depths and equilibrated at those conditions to form these high-pressure granulites, which were then emplaced into the crust quickly. During the rapid exhumation of these rocks, the earlier high-pressure assemblages were overprinted by the later low- to medium-pressure assemblages, that is, the high-pressure granulite belt formed in the syntaxis. (2) The Namula thrust system is an important tectonic boundary in the syntaxis, or even in the Higher Himalaya more generally.     

Study of annual mass balance(2011–2013) of Rikha Samba Glacier,Hidden Valley,Mustang, Nepal

Although Himalayan glaciers are of particular interest in terms of future water supplies, regional climate changes, and sea-level rises, little is known about them due to lack of reliable and consistent data. There is a need for monitoring these glaciers to bridge this knowledge gap and to provide field measurements necessary to calibrate and validate the results from different remote sensing operations. Therefore, glaciological observations have been carried out by the Cryosphere Monitoring Project(CMP) since September 2011 on Rikha Samba Glacier in Hidden valley, Mustang district in western Nepal in order to study its annual mass balance. This paper presents the first results of that study. There are 10 glaciers in Hidden Valley, named G1, G2, G3, up to G10. Of these, G5 is the Rikha Samba Glacier, which has the largest area(5.37 km2) in this valley and the highest and lowest altitudes(6,476 and 5,392 m a.s.l., respectively). The glacier mass balance discussed in this paper was calculated using the glaciological method and the equilibrium line altitude(ELA). The glacier showed a negative annual point mass balance along the longitudinal profile of its lower part from September 10, 2011 to October 3, 2012. Stake measurements from October 4, 2012 to September 30, 2013 indicated a negative areal average of annual mass balance-0.088±0.019 m w.e. for the whole glacier. Based on these observations, the ELA of the Rikha Samba Glacier is estimated at 5,800 m a.s.l. in 2013. This negative balance may be due to rising air temperatures in the region, which have been incrementally rising since 1980 accompanied by little or no significant increase in precipitation in that period. The negative mass balance confirms the general shrinking trend of the glacier.     

塔里木盆地两种重要的圈闭型式及其与喜山期油气关系

在塔里木盆地众多的圈闭类型中，中生界披覆背斜圈闭和以下古生界为主的断块潜山（或潜山）圈闭是最重要的两种高产圈闭型式，此两种圈闭均主要形成于中生代，它们所富集的油气均主要是喜山期以来生成的油气。披覆背斜圈闭封闭样多为单封闭层整合型，而断块潜山（或潜山）圈闭封闭样成式为不整合型（其中许多尚属多封闭层圈闭），故从理论上看，中生界披覆背斜圈闭封闭和储聚油气能力要优于古生界断块潜山（或潜山）圈闭，塔北勘探实     

The P–T–t evolution of the exhumed Himalayan metamorphic core in the Likhu Khola region,East Central Nepal

The recent identification of multiple strike‐parallel discontinuities within the exhumed Himalayan metamorphic core has helped revise the understanding of convergence accommodation processes within the former mid‐crust exposed in the Himalaya. Whilst the significance of these discontinuities to the overall development of the mountain belt is still being investigated, their identification and characterization has become important for potential correlations across regions, and for constraining the kinematic framework of the mid‐crust. The result of new phase equilibria modelling, trace element analysis and high‐precision Lu–Hf garnet dating of the metapelites from the Likhu Khola region in east central Nepal, combined with the previously published monazite petrochronology data confirms the presence of one of such cryptic thrust‐sense tectonometamorphic discontinuities within the lower portion of the exhumed metamorphic core and provides new constraints on the P–T estimates for that region. The location of the discontinuity is marked by an abrupt change in the nature of P–T–t paths of the rocks across it. The rocks in the footwall are characterized by a prograde burial P–T path with peak metamorphic conditions of ~660°C and ~9.5 kbar likely in the mid‐to‐late Miocene, which are overlain by the hanging wall rocks, that preserve retrograde P–T paths with P–T conditions of >700°C and ~7 kbar in the early Miocene. The occurrence of this thrust‐sense structure that separates rock units with unique metamorphic histories is compatible with orogenic models that identify a spatial and temporal transition from early midcrustal deformation and metamorphism in the deeper hinterland to later deformation and metamorphism towards the shallower foreland of the orogen. Moreover, these observations are comparable with those made across other discontinuities at similar structural levels along the Himalaya, confirming their importance as important orogen‐scale structures.     

Diversity, Distribution and Prioritization of Fodder Species for Conservation in Kullu District, Northwestern Himalaya, India

In the Indian Himalayan Region predominantly rural in character, livestock is one of the main sources of livelihood and integral part of the economy. Livestock mostly rely on fodder from wild. The diversity, distribution, utilization pattern, nativity, endemism, rarity, seasonality of availability, nutritive values, perceived economic values and pressure use index of livestock have not been studied. The present study attempts to enumerate 150 species of fodder representing trees (51 spp.), shrubs (54 spp.) and herbs (45 spp.). Poaceae (19 spp.) and Fabaceae (13 spp.) amongst families and Salix (6 spp.), Ficus, Clematis, and Desmodium (5 spp., each) amongst genera are rich in species. Maximum species were found in the 1801 ~ 2600 m zone, and the remaining two zones showed relatively low diversity. Out of the 150 species, 109 are used in summer, 5 winter and 36 throughout year. During rainy season, mostly grasses are used as fodder. Only 83 species are native to the Himalayan region, one species, Strobilanthus atropuroureus is endemic and 35 species are near endemic. The nutritive values of the fodder species were reviewed, and economic values and status of the species were also assessed. The pressure use index of the species was calculated on the basis of cumulative values of the utilization pattern, altitudinal distribution, availability, status, nativity and endemism. Amongst the species, Grewia oppositifoilia, Morus serrata, Indigofera heterantha, Quercus leucotrichphora, Ulmus villosa, U. wallichiana and Aesculus indica showed highest PUI indicating high preference and pressure. Season wise prioritization of the species for different altitudinal zones has been done. Appropriate strategy and action plan have been suggested for the conservation and management of fodder species.     

西藏南部晚始新世打拉埃达克质花岗岩及其构造动力学意义

打拉二云母花岗岩岩体位于雅拉香波穹隆的东南,侵入到中生代以前的变质岩系(眼球状花岗质片麻岩和石榴黑云母片麻岩)和特提斯沉积岩(页岩和砂岩)中,主要由石英、斜长石、钾长石、黑云母和白云母组成,形成于～44.3Ma。打拉二云母花岗岩地球化学特征表明:打拉花岗岩具有高Al_2O_3(16.0%～17.0%)、Na_2O/K_2O(1.2)以及A/CNK比值(1.05),表明打拉花岗岩为富钠过铝质花岗岩;轻稀土(LREE)富集,重稀土(HREE)相对亏损,HREE中的Ho到Lu元素有变平的特征((Ho/Lu)_N=1.11～1.46);具有微弱或无Eu异常,Eu/Eu~*=0.87～0.95;较高的初始Sr同位素比值(~(87)Sr/~(86)Sr(i)=0.71754～0.71785)和较低的初始Nd比值(ε_(Nd)(i)=-9.15～-12.4)。打拉花岗岩具有高Sr含量(为355×10~(-6)～416×10~(-6))和Sr/Y的比值(59.1～71.5)、高La/Yb比值、低Y及HREE亏损的特征,与埃达克质花岗岩类似。上述特征表明打拉花岗岩是在较高压力条件下,以角闪岩为主的深部岩石部分熔融的结果。     

藏东雅鲁藏布江大拐弯蛇绿岩变基性岩类岩石地球化学再研究

在1:25万区域地质填图和专题研究的基础上,再次对喜马拉雅东构造结地区雅鲁藏布江蛇绿混杂带中变基性岩的常量元素、微量元素和Sr-Nd-Pb同位素地球化学特征进行了深入研究,进一步阐明了SSZ型蛇绿岩的成因。变基性岩类可分为具有玻安岩类、IAT和OIB特征的3类。玻安岩类为LREE呈略亏损—平坦型,稀土元素总量低,∑REE为7.56×10-6～20.89×10-6,富相容元素Cr、Ni和常量成分MgO、Al2O3,形成于弧前环境。IAT类为本带的主要类型,在蜘蛛图上有一定的Nb、Ta亏损,REE为大致平坦型,稀土元素总量低,∑REE为37.84×10-6～55.75×10-6。OIB类为LREE较富集型,稀土元素总量高,∑REE为102.09×10-6～240.95×10-6,与IAT和MORB相比,具较高的La、Nb、P、Ti含量,而相容元素Cr、Ni等含量较低。Sr、Nd、Pb同位素组成反映PREMA(或BSE)和EMI提供了源区,暗示未分异的原始地幔和下地壳参与形成了原始岩浆。推测新特提斯洋盆演化经历了较早的地幔柱、洋岛阶段,形成了MORB-OIB组合;较晚期为洋内弧阶段,形成了SSZ型蛇绿岩和IAT组合。