Discovery and implications of the high-pressure pelitic granulite from the Jiaobei massif

The high pressure pelitic granulite with peak assemblage of garnet kyanite ternary feldspar muscovite rutile was discovered in Qixia area in the Precambrian Jiaobei massif, where high pressure basic granulites are widely distributed. The metamorphic peak conditions for the pelitic granulite were calculated as T=800-840℃ and P=1.0-1.25 GPa on the basis of P-T pseudosection. The post peak P-T path is characterized first by an isothermal decompression (ITD) pattern and then by an isobaric cooling (IBC) pattern, indicating a geodynamic process related to thinning of thickened continental crust.     

现代藏族艺术中的更敦群培和安多强巴——艺术创作方法比较研究

更敦群培和安多强巴是二十世纪西藏重要的写实艺术家,他们的绘画作品和艺术主张给当时的西藏艺术带来新的面貌。文章通过对近年来出版的文献、同时代摄影作品资料以及更敦群培和安多强巴教育经历、艺术活动和各个时期重要绘画作品的深入研究,分析了各自的艺术特点及形成的原因。     

SHRIMP U-Pb zircon geochronology of granulites at Rimana （Southern Tibet） in the central segment of Himalayan Orogen

TheCenozoicHimalayanorogenisimportantinun-derstandingcontinentaldynamicprocesses.Lowercrustal,high-grademetamorphicrockshaverecentlybeendiscov-eredinNamcheBarwaandParmir,i.e.therespectivere-gionsofeasternandwesternsyntaxisoftheorogen[1—4].Eclogitesthatunderwentgranulite-faciesmetamorphismhaverecentlybeenreportedintheCadaareatotheeastofMountEverestinthecentralsegmentoftheHimalayanorogen[5].WiththehelpofthegeologicalsurveyofDing-gyeCountyandChentangSheets(scale1︰250000),high-pressuremafic…     

Confirmation of ultrahigh-temperature metapelitic granulite in the Altay orogen and its geological significance

Through petrography, mineral compositions and P-T estimate results, an ultrahigh-temperature(UHT) metapelitic granulite has recently been identified from near Kalasu in the east of Altay city, with an assemblage gt-opx-silcd-sp-bt-pl-qtz. The orthopyroxene has a high-Al feature, and its Al2O3 content is as high as 8.7 wt%, indicating a UHT metamorphic condition. Its peak metamorphic condition is estimated as: P = *0.80 GPa, T = *960 °C. Metamorphic textural relations and P-T estimate results show a post-peak near-isobaric cooling anticlockwise P-T path. Zircon U-Pb age results(271 ± 5 Ma) support that the UHT metamorphic event in the region occurred in the Permian. The identification of the UHT metapelitic granulite from near Kalasu confirms the existence of the Permian UHT metamorphism in the Altay orogen, implying that the Permian extensional tectonic setting of a high-heat flow in the southern part of the Altay orogen may be closely associated with the Permian Tarim mantle plume activity.     

Sm-Nd age dating of high-pressure granulites and amphibolite from Sanggan area, North China craton

The high pressure (HP) metamorphic age has been dated to HP rocks from the Sanggan area, North China craton. We have got garnet+whole rock isochron ages of (1 842±38) Ma for HP granulite, and (1 856 ± 26) Ma for HP amphibolite. The Sm-Nd whole rock isochron of HP granulites give out an age of (1 870±150) Ma with Nd depleted mantle model age of (2 402—2 482) Ma. Considering the Nd isotope homogenization during the peak metamorphism of the HP granulite, Sm-Nd closure temperature and the retention of Nd isotopic memory in garnets partially broken down during decompression, all these isochron ages are thought to be HP metamorphic age. Furthermore, we proposed that the HP metamorphism took place at the end of Paleoproterozoic during the large-scale collision and assembly of the North China craton.     

SHRIMP U-Pb dating and Hf isotopic analyses of zircons from the mafic dyke swarms in central Qiangtang area, Northern Tibet

In the ＂Central Uplift＂ of Qiangtang, Northern Tibet, a large scale of mafic dyke swarms extended in E-W direction. Zircon SHRIMP U-Pb dating on two representative samples of diabase dyke yield weighted mean ages of 284 ± 3 Ma and 302 ± 4 Ma, respectively, suggesting they emplaced in the Late Carboniferous to Early Permian. Zircon ^176Hf/^177Hf ratios range from 0.282852 to 0.283041, with ,εHf（t） values of ＋12.1 to ＋12.2 and Hf modal （TDM） ages of ～440-460 Ma. These data indicate that these mafic dykes were mainly derived from the depleted mantle. In addition, geochemical data suggest that these mafic dyke swarms are of intra-plate origin. Therefore, the mafic dyke swarms represent products during the extensional process associated with the opening of the Paleo-Tethys Ocean in the area.     

西藏南部雅鲁藏布江缝合带的沉积－构造演化

西藏南部雅鲁藏布江缝合带从晚侏罗世至今可能经历了新特提斯洋的两期俯冲作用,早期俯冲从晚侏罗世至早白垩世,以桑日群和恰布林组为代表,雅鲁藏布江古蛇绿岩在此期形成;而晚期俯冲从中白垩世至始新世,以混杂岩、雅鲁藏布江蛇绿岩和日喀则为代表,拉孜－浪卡子断裂可能代表了印度大陆与亚洲大陆碰撞的实际地表位置,由此提出包括新特提斯洋两期俯冲作用在内的五个阶段的雅鲁藏布江缝合带沉积－构造演化过程。     

羌塘晚三叠世-早白垩世裂陷盆地基底构造

探讨羌塘盆地基底构造,为油气远景评价提供依据.通过对十多年来积累的地质、地球物理资料和物性资料的研究,在羌塘盆地识别出2个基底界面,一是前寒武系结晶基底顶面的密度(重力异常)界面,二是上三叠统顶部的磁性(航磁异常)界面.根据最新的航磁异常资料,对晓三叠世-早白垩世被动大陆边缘裂陷-拗陷盆地的基底构造单元进行分析,划分出2个Ⅰ级构造单元,4个Ⅱ级构造单元,23个Ⅲ级构造单元.在此基础上识别出3个裂陷槽、2个隆起带,圈定出3个相对应的生烃凹陷,2个发育礁、滩相碳酸盐岩储集层的隆起带,圈定了3个油气运移集聚的远景区.     

西藏农牧区社会保障制度路径选择

文章通过构建非缴费型农牧区养老保险模式、构建覆盖所有农牧民的健康保障制度、告别扶贫计划,建立农牧区救助机制三条路径,采取收入补充型保障水平的定位、普遍保障型给付条件的确定、财政补贴型和城镇——农村转移补贴型结合的筹资方式、均一给付型给付机制的确定、构建新型农牧区合作医疗制度、建立农牧区医疗救助制度、建立农牧区低保制度的法律规范、界定新的高原贫困线及救助标准、坚持灾民救助行动、提升五保供养层次建立城镇农牧民工的过渡性社会保险等对策,提出了构建新世纪西藏农牧区正式的多层次的保障体系的具体思路。     

松辽盆地梨树断陷基底结构特征

梨树断陷是松辽盆地南部印支—燕山运动时期形成,在北东—北北东向和北西-北北西向基底断裂的基础上发育起来的断陷盆地。通过对1∶50 000高精度重磁资料处理,结合钻井揭露认为,基底岩性主要为变质岩,局部有碳酸盐岩出露,大体上有海西期、印支—早燕山期2期火成岩侵入体,推测索伦-林西缝合带由此经过。该区基底结构特征和基底断裂,奠定了晚侏罗世之前盆地的构造形态,并且影响着后期盆地的地层格架和充填样式。     

阿底峡在西藏传法历史考

文章从历史学角度,把迎请阿底峡来藏的经过、阿底峡来藏后著书立说、厘清藏传佛教修习次第、以其著名的＂道次第＂理论影响藏传佛教各教派等的脉络置于当时复杂的社会历史中进行考察,分析了阿底峡来藏传法的社会背景,从不同角度评述和分析了阿底峡在西藏开展的弘法活动及其对藏传佛教产生的影响,并对作为历史人物的阿底峡及其独特理论予以评价。     

Zircon U-Pb dating of basement gneisses in the super-large Bayan Obo REE-Fe-Nb deposit,Inner Mongolia

Zircon U-Pb ages have been determined for basement gneisses in the Bayan Obo REE-Fe-Nb deposit. On the U-Pb concordia diagram data of three samples yield upper intercept ages of 1948-1917 Ma. Thus, these basement gneisses are of Paleoproterozoic. Rock association of these basement gneisses includes tonalite, syenite and paragneiss, not belonging to a sedimentary package. It is more appropriate to consider this association as a basement complex rather than a stratigraphic "Group".     

新疆若羌县中坡山地区褶皱基底叠加褶皱构造解析

新疆北山西段中坡山地区褶皱基底中元古界白湖群中普遍存在新月形、蘑菇形及线形紧闭褶皱,构造解析表明它们是由叠加褶皱形成的复杂露头干涉形式.区内第一期褶皱为NNW向、轴面东倾的同斜-平卧褶皱;第二期褶皱为NEE向紧闭直立-倒转背形向斜、向形背斜、背形背斜及向形向斜.该区叠加褶皱的形成与中元古代初始裂谷闭合及华力西晚期克拉通裂谷闭合密切相关.     

APP改性沥青油毡在地下防水中的应用

结合某综合楼的地下室防水工程实践,介绍了APP改性沥青防水卷材的材料性能、施工工艺及施工保护措施的相关要求.     

Classification and Assessment of Freeze-Thaw Erosion in Tibet, China

Based on the analysis of existing relevant research result, a theoretical basis for the defining freeze-thawerosion zones of Qinghai-Tibet Plateau was been put forward, and a equation for calculating the altitude of the lower bound of the freeze-thaw erosion zones of Qinghai-Tibet Plateau was been established in this paper. Moreover, the freeze-thaw erosion zones in Tibet was been identified by using Geographical Information System (GIS) software. Next, based on thecomprehensive analysis of impact factors of freeze-thaw erosion, this paper chooses annul temperature range, slop and vegetation as three indexes, works out the criteria for relative classification of freeze-thaw erosion, and realizes the relative classification of the freeze-thaw erosion in Tibet under the support of GIS software. Then, a synthetic assessment of freeze-thaw erosion in Tibet was been done according to the relative classification result.     

Age of Anzishan granulites in the Mianxian-Lueyang suture zone of Qingling orogen: With a discussion of the timing of final assembly of Yangtze and North China craton blocks

Many granulite blocks have been recently discovered in the Anzishan area, Mianxian County, Shaanxi Province, in the central segment of the Mianxian-Lueyang suture zone. Sm-Nd isochron and 40Ar/39Ar ages of mineral samples of granulites from this area are reported in the note. The granulite mineral samples give a Sm-Nd isochron age of t=(206 ( 55) Ma (2(), with INd = 0.51302(7(2() and MSWD = 1.6, and a biotite 40Ar/39Ar plateau age of (199.7(1.7) Ma (2(). The formation and uplift of the granulites were related to subduction of the Yangtze block beneath the South Qinling microcontinent and their collision and the final amalgamation of the Yangtze and Sino-Korean craton blocks in the Indosinian, and their age is consistent with or close to those of the Dabie ultrahigh-pressure and high-pressure metamorphic rocks, so have great tectonic significance.     

Diatom-based reconstruction of Holocene environmental changes in Angren Lake, Southern Tibet

Based on the diatom analysis the climatic sequence between 11 000 and 6 000 aBP in Angren, southern Tibet is established, i.e. cold period (11 095-9 970 aBP)→temperate period (9 970-9 870 aBP)→Anathermal (9 870-9 770 aBP)→cool-dry period (9 770-8 740 aBP) →super-megathermal (8 740-8 590 aBP)→Megathermal (8 590-5 970 aBP). And the opinion that the reaction of diatom to temperature change is more sensitive than to other ecological factors has been pointed out and certified.