排序方式： 共有48条查询结果，搜索用时 15 毫秒
1.
Orogenic and Anorogenic Granitoids in the Altay Mountains of Xinjiang and Their Discrimination Criteria 总被引：1，自引：0，他引：1
On the basis of field geological studies of the granotoids in the region, mineralogical, petrological, geochemical(including stable isotope geochemical) and isotopic geochronological investigations were carried out on selected representative granitic bodies of various types. The authors have concluded that, apart from the bodies of the orogenic granitoid series, there also exist intrusions of the anorogenic granitoid series in the region. The intrusives of the two series were formed not only in different ages and tectonic environments, but also were derived from different sources of materials. Moreover, they are associated with different mineralizations, belonging to different minerologenetic series(Cheng et al., 1983). They show distinctly a series of discriminative criteria. The problems under discussion in the present paper are of important theoretical and practical significance in the studies of granites of the orogenic belt, particularly the studies of the genesis and related metallogeny of the granites of the region. 相似文献
2.
北秦岭官坡地区高压—超高压榴辉岩岩相学及变质作用研究 总被引：19，自引：2，他引：19
北秦岭官坡地区的榴辉岩及含柯石英榴辉岩产在帮岭岩群的北侧，主要由绿辉石和石榴石组成，部分石榴石和绿辉石中含柯石英包体。此外还含有退变质的多硅白云母、角闪石、黝帘石和纳长石等矿物，根据变质矿物之间的替代关系及共生组合规律，榴辉岩退变质作用可划分为四个阶段，各阶段代表性矿物组合依次为：柯石英＋绿辉石＋石榴石；石英＋绿辉石＋石榴石；多硅白云母＋绿辉石＋石榴石＋石英；角闪石＋斜长石＋白云母＋黑云母。这四个 相似文献
3.
Expeditions to Muztagata (in the eastern Pamirs) during the summer seasons of 2002 and 2003 collected precipitation samples
and measured their oxygen isotopes. The δ
18O in precipitation displays a wide range, varying from −17.40‰ to +1.33‰ in June-September 2002 and from −22.31‰ to +4.59‰
in May-August 2003. The δ
18O in precipitation correlates with the initial temperature of precipitation during the observing periods. The positive correlation
between δ
18O and temperature suggests that δ
18O can be used as an indicator of temperature in this region. The δ
18O values in fresh-snow samples collected from two snow events at different elevations on the Muztagata Glacier show a strong
“altitude effect”, with a ratio of nearly −0.40% per 100 m from 5500 m to 7450 m. 相似文献
4.
Expeditions during the summers of 2002 and 2003 implemented continuous monitoring of near-surface (2 m height) atmospheric
CO2 and H2O concentrations at the 4500 m elevation on Muztagata. The resultant data sets reveal a slight decrease of CO2 concentrations (of about 5 μmol·mol-1) and changes in the diurnal variations from the end of June to the middle August. The daily maximum CO2 concentrations occur between 02:30-05:30 AM (local time) and the minimum levels occur between 12:00-15:30 PM. The atmospheric
CO2 concentrations in the summer of 2002 were around 5 μmol·mol-1 lower than those during the same period of 2003, whereas the diurnal amplitude was higher. In contrast, we found that the
daily mean atmospheric H2O content in 2003 was much lower than that in 2002 and there exists a striking negative correlation between CO2 and H2O concentrations. We therefore suggest that the near-surface atmospheric CO2 concentration is affected not only by photosynthesis and respiration, but also by the air H2O content in the glaciated region around Muztagata. 相似文献
5.
YAO Tandong GUO Xuejun Lonnie Thompson DUAN Keqin WANG Ninglian PU Jianchen XU Baiqing YANG Xiaoxin SUN Weizhen 《中国科学D辑(英文版)》2006,49(1)
The 213 m ice core from the Puruogangri Ice Field on the Tibetan Plateau facilitates the study of the regional temperature changes with its δ18O record of the past 100 years. Here we combine information from this core with that from the Dasuopu ice core (from the southern Tibetan Plateau), the Guliya ice core (from the northwestern Plateau) and the Dunde ice core (from the northeastern Plateau) to learn about the regional differences in temperature change across the Tibetan Plateau. The δ18O changes vary with region on the Plateau, the variations being especially large between South and North and between East and West. Moreover, these four ice cores present increasing δ18O trends, indicating warming on the Tibetan Plateau over the past 100 years. A comparative study of Northern Hemisphere (NH) temperature changes, the δ18O-reflected temperature changes on the Plateau, and available meteorological records show consistent trends in overall warming during the past 100 years. 相似文献
6.
δ~(18)O record and temperature change over the past 100 years in ice cores on the Tibetan Plateau 总被引：6，自引：0，他引：6
Lonnie Thompson 《中国科学D辑(英文版)》2006,(1)
1 IntroductionMeteorological stations on the Tibetan Plateau are few in number and uneven in distribution, with a majority concentrated in the east and south. No stations exist so far within the large expanse in the middle or west of the Plateau. Moreover… 相似文献
7.
Natural Hazards - This article aims to provide a quantitative study of immediate food supplies based on a three-stage analysis. Firstly, a numerical autoregressive integrative moving average... 相似文献
8.
9.
低纬地区平流层准零风层时空分布特征分析 总被引：1，自引：0，他引：1
利用ERA-Interim逐日再分析资料,使用EOF（Empirical Orthogonal Function）等统计方法,分析了中国低纬地区平流层准零风层（Quasi-Zero Wind Layer,QZWL）的时空分布特征,旨在为平流层飞艇寻找合适的运行区域及时段。低纬地区QZWL主要受到热带平流层大气环流季节性变化和平流层准两年振荡（Quasi-BiennialOscillation,QBO）的影响。在二者共同作用下,低纬地区QZWL高概率带可分为南北两支:“北支”出现在10月至次年4月间,QBO东风位相时期,“北支”中心纬度基本维持在20°N附近,西风位相时期,“北支”中心纬度随高度降低南移明显;“南支”仅出现在QBO西风位相期间,5~11月在5°N附近,其余时段与“北支”合并,可以认为是“北支”向南延伸。通过对比海口站和南沙站Weibull概率密度函数与风速资料的拟合结果,表明Weibull分布可以很好拟合不同QBO位相下平流层逐月风速频率分布,根据Weibull分布计算特定的累积概率风速值,可以作为选取适宜平流层飞艇运行的低风速风场的判据。海口站30~50 hPa高度11月至次年4月、南沙站50~70 hPa高度QBO西风位相时期全年均较为适合平流层飞艇运行。 相似文献
10.
东秦岭造山带核部杂岩，在高温高压环境下曾出现大量流体，由溶解作用产生的流体在变形分解带内运移，形成古水热循环系统，该水热系统使岩石中如铀等大离子富集成矿，水岩相互作用造成秦岭杂岩中稀土元素四重分布效应． 相似文献