Mantle Branch Structure in the South-Central Segment of the Da Hinggan Mts.,Inner Mongolia and Its Ore-controlling Role

Mantle branch structure is the third tectonic unit of multiple evolution of a mantle branch. It is not only the main mechanism of intercontinental orogeny, but also an important ore-forming and ore-control structure. Studies on geotectonic evolution, regional geological characteristics and oreforming and ore-control structures have shown that since the Mesozoic the Da Hinggan Mts. region has entered a typical intercontinental orogenic stage, and it is closely related to mantle branch activities. The south-central segment of the Da Hinggan Mts. is a typical mantle branch structure and possesses obvious magmatic-metamorphic complexes in the core, detachment slip beds in the periphery and overlapped fault depression basins. Moreover, all of these are the principal factors leading to ore formation and ore control in the region. This paper also further explores the mechanism of mineralization in the south-central segment of the Da Hinggan, summaries the rules of mineralization, puts forward the models of mineralization and points out future ore-exploring orientation.

Ar-Ar Dating on the Metallogenesis of the Dongchuang Gold Deposit in the Xiaoqinling Area

The Dongchuang gold deposit in the Xiaoqinling area is an orogenic-type lodegold deposit. It is one of the few superlarge (>100 t Au) deposits in China. Although it has beenargued that it was formed in the Mesozoic, related isotopic age data have not been reported inprevious studies. Based on detailed geological study, the authors have carried out isotopic datingon various metallogenic generations. The ore-forming process of the Dongchuang gold deposit consistsof four stages: coarse-grained pyrite-bearing quartz veins (stage I), fine-grained pyrite-quartzveinlets (stage II), multi-sulfides (stage III) and carbonate-quartz veinlets (stage IV). Ar-Ardating on mineral separates of stages I, II and III yields plateau ages of 142.9 +- 2.9 Ma, 132.2 +-2.6 Ma and 128.3 +- 6.2 Ma, respectively. Sericite separates from stage II assemblage also yield anAr-Ar isochron age of 132.6 +- 2.7 Ma, similar to the Ar-Ar plateau age. These results suggest thatthe Dongchuang gold deposit was mainly formed during 143-128 Ma, coinciding with the authors'geological observations and previous hypothesis. This ore formation is coeval with theregional-tectonic transition from collisional compression to extension, strongly showing that thedecompression-geothermal increase regime during compression-to-extension transition is the mostconducive geodynamic environment to orogenic-type gold mineralization.

3-D Geological Modeling-Concept,Methods and Key Techniques

3-D geological modeling plays an increasingly important role in Petroleum Geology, Mining Geology and Engineering Geology. The complexity of geological conditions requires different modeling methods in different situations. This paper summarizes the general concept of geological modeling; compares the characteristics of borehole-based modeling, cross-section based modeling and multi- source interactive modeling; analyses key techniques in 3-D geological modeling; and highlights the main difficulties and directions of future studies.

TECTONIC ORE-CONTROLLING IN THE MIDDLE-SOUTHERN SEGMENT OF DA HINGGAN LING, NORTHEAST CHINA

Studies on geotectonic evolution, regionally geological characteristics and ore-forming and ore-controlling structures have shown that since the Mesozoic the Da Hinggan Ling region has entered the typical intercontinental orogenic stage, which appears to be closely related to mantle plume activities. Da Hinggan Ling is a typical mantle branch structure and possesses obvious magmatic-metamorphic complexes in the core, detachment slip beds in the periphery and overlapped fault depression basins. Moreover, all these are the principal factors leading to ore formation and ore controlling in the region. This paper also further explores the mechanism of mineralization in the middle-southern segment of Da Hinggan Ling, summaries the rules of mineralization, puts forward the models of mineralization and points out the ore-search orientations in the future time.

Q value of anelastic S-wave attenuation in Yunnan region

The study of seismic attenuation property is a major subject in seismology. Seismic waves recorded by seismic stations （seismographs） contain source effect, seismic wave propagation effect, site response of seismic stations and instrumental response. The path effect of seismic wave propagation, site response of seismic stations and instrumental response must be taken out in the study of source property with seismic data. The path effect of seismic wave propagation （seismic attenuation） involves an important influential factor, the anelastic attenuation of medium, which is measured with quality factor Q, apart from geometric attenuation with the distance. As a basic physical parameter of the Earth medium, Q value is essential for quantitative study of earthquakes and source property （e.g. determination of source parameters）, which is widely used in earthquake source physics and engineering seismology.

Quantitative assessment and analysis on the dynamic change of ecological capital in arid areas

生态的资本是生物资源的直接价值和生态系统的生态的服务功能价值的求和。在 RS ， GPS 和 GIS 的支持下面，在这篇论文，估计生态的资本的 基于RS 的量的测量模型每由包括 Landsat TM 数据使用生态的参数统一区域基于生态的资本的价值上的传统的生态学理论和研究被开发， CBERS 卫星数据，气象学的数据， MODIS 卫星数据，陆地封面数据和测量地的数据。在在 1990， 1995 和 2003 的 Changji Hui 自治的府的生态的资本的空间与时间的分发上的案例研究被执行，并且在府的生态的资本的动态变化被测量并且与 GDP 相比。在学习区域的生态的资本的空间分发的地图被制定，并且生态的资本的空间分发的特征被分析。结果证明在在 1990， 1995 和 2003 的府的生态的资本的价值是 1.473 68 吗？？