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Yang Z.-J.,Sun Yat Sen University | Yang Z.-J.,Guangdong Provincial Key Laboratory of Mineral Resource Exploration and Geological Processes | Liang R.,Sun Yat Sen University | Zeng X.-Q.,Sun Yat Sen University | And 4 more authors.
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2012

The natural polycrystalline diamonds from the Mengyin kimberlite pipes can be classified as the euhedral faceted polycrystalline diamonds and anhedral rounded polycrystalline diamonds. The results of micro-FTIR spectra characterization of the polycrystalline diamonds show that the concentration of nitrogen is low, varying from 16.69 to 72.81 microgram per gram and is different among different diamond grains or position in polycrystalline diamonds. The euhedral faceted polycrystalline diamonds are I aAB type and have higher concentration of A-center defects than B-center defects. Most of the anhedral rounded polycrystalline diamonds are I aAB type and have higher content of B-center defects. A minority of the anhedral rounded polycrystalline diamonds have C-center, A-center and B-center defects simultaneously. The polycrystalline diamonds probably originated from the relatively deeper mantle and were not formed in diamond nucleation stage, but in the diamond growth period or some special conditions after the diamond grains were formed already. Furthermore, the euhedral faceted polycrystalline diamonds were formed slightly later and the anhedral rounded polycrystalline diamonds were formed obviously earlier than the diamond single crystals from the Mengyin kimberlite pipes. Source


Zeng X.-Q.,Sun Yat Sen University | Zheng Y.-L.,Sun Yat Sen University | Yang Z.-J.,Sun Yat Sen University | Yang Z.-J.,Guangdong Provincial Key Laboratory of Mineral Resource Exploration and Geological Processes | And 2 more authors.
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2013

The FTIR and Raman spectra of 10 diamonds from Yuanshui, Hunan province show that the alluvial diamonds from this area are mostly IaAB type, with a significant character that the A-center is enriched relatively; the nitrogen concentration in the diamonds is between 38.20 and 840.67 μg·g-1, which has a tremendous distinction in different crystal. The residence time of the diamonds in the mantle are between 0.043 and 3.315 Ga, which is also has a great difference in different diamond grains. The remotest residence time (3.315 Ga) of one diamond is older than the most aged rock (3.285 Ga) in Xiang-E-Qian-Gui contiguous zone. A remarkable environment change had took place during the process of diamonds formation. The formation depth of dodecahedral diamonds is deeper than that of the octahedral ones. Source


Yang L.,Sun Yat Sen University | Yang L.,Guangdong Provincial Key Laboratory of Mineral Resource Exploration and Geological Processes | Hou W.,Sun Yat Sen University | Hou W.,Guangdong Provincial Key Laboratory of Mineral Resource Exploration and Geological Processes | And 3 more authors.
Computers and Geosciences | Year: 2016

Most current multiple-point statistics (MPS) algorithms are based on a sequential simulation procedure, during which grid values are updated according to the local data events. Because the realization is updated only once during the sequential process, errors that occur while updating data events cannot be corrected. Error accumulation during simulations decreases the realization quality. Aimed at improving simulation quality, this study presents an MPS algorithm based on global optimization, called GOSIM. An objective function is defined for representing the dissimilarity between a realization and the TI in GOSIM, which is minimized by a multi-scale EM-like iterative method that contains an E-step and M-step in each iteration. The E-step searches for TI patterns that are most similar to the realization and match the conditioning data. A modified PatchMatch algorithm is used to accelerate the search process in E-step. M-step updates the realization based on the most similar patterns found in E-step and matches the global statistics of TI. During categorical data simulation, k-means clustering is used for transforming the obtained continuous realization into a categorical realization. The qualitative and quantitative comparison results of GOSIM, MS-CCSIM and SNESIM suggest that GOSIM has a better pattern reproduction ability for both unconditional and conditional simulations. A sensitivity analysis illustrates that pattern size significantly impacts the time costs and simulation quality. In conditional simulations, the weights of conditioning data should be as small as possible to maintain a good simulation quality. The study shows that big iteration numbers at coarser scales increase simulation quality and small iteration numbers at finer scales significantly save simulation time. © 2016 Elsevier Ltd. Source


Lu W.-C.,Sun Yat Sen University | Lu W.-C.,Guangdong Provincial Key Laboratory of Mineral Resource Exploration and Geological Processes | Yang Z.-J.,Sun Yat Sen University | Yang Z.-J.,Guangdong Provincial Key Laboratory of Mineral Resource Exploration and Geological Processes | And 10 more authors.
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2013

The XRD, FTIR and Raman spectrum were employed to study the characters of quartz from three types of rock samples, which are mineralized rock sample, near ore body rock sample and far away from ore body rock sample in Heliao lead-zinc polymetallic ore district. The research shows that the quartz in the mineralized rock and far away from ore body rock is pure, while the quartz in near ore body rock contains a small amount of impurities. But such small amounts of impurities did not cause apparent change in the quartz lattice parameters. From far away from ore body rock→near ore body rock→mineralized rock, the crystallinity and order degree of quartz are higher and higher. And the quartz in the mineralized rock has a trend to change into low symmetry quartz. It's a unique to mineralized rock that the quartz's absorption peak at 1 050 cm-1 was split into two strongest ones. It can be used as the signs of whether exists mineralization. The cause for the quartz microstructure changes may be related to the activities of late mineralized hydrothermal fluids. Late hydrothermal influence was very weak to the quartz far away from ore body rock. And through the impact of the multi-stage hydrothermal effect, the quartz in mineralized rock may be purified by recrystallization and structural adjustment. However the quartz in near ore body rock didn't have enough hydrothermal influence, so it's not pure. Genealogy research technology is a useful technique for in-depth exploration of study area mineralization process and metallogenic regularity. Source


Hou W.,Sun Yat Sen University | Hou W.,Guangdong Provincial Key Laboratory of Mineral Resource Exploration and Geological Processes | Yang L.,Sun Yat Sen University | Yang L.,Guangdong Provincial Key Laboratory of Mineral Resource Exploration and Geological Processes | And 9 more authors.
Computers and Geosciences | Year: 2016

Urban underground spaces (UUS), especially those containing natural resources that have not yet been utilized, have been recognized as important for future sustainable development in large cities. One of the key steps in city planning is to estimate the quality of urban underground space resources, since they are major determinants of suitable land use. Yet geological constraints are rarely taken into consideration in urban planning, nor are the uncertainties in the quality of the available assessments. Based on Fuzzy Set theory and the analytic hierarchy process, a 3D stepwise process for the quality assessment of geotechnical properties of natural resources in UUS is presented. The process includes an index system for construction factors; area partitioning; the extraction of geological attributes; the creation of a relative membership grade matrix; the evaluation of subject and destination layers; and indeterminacy analysis. A 3D geological model of the study area was introduced into the process that extracted geological attributes as constraints. This 3D geological model was coupled with borehole data for Foshan City, Guangdong province, South China, and the indeterminacies caused by the cell size and the geological strata constraints were analyzed. The results of the case study show that (1) a relatively correct result can be obtained if the cell size is near to the average sampling distance of the boreholes; (2) the constraints of the 3D geological model have a major role in establishing the UUS quality level and distribution, especially at the boundaries of the geological bodies; and (3) the assessment result is impacted by an interaction between the cell resolution and the geological model used. © 2016 Elsevier Ltd. Source

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