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The uplift of the Tibetan Plateau significantly affected the global climate system. However, the timing of its uplift and the formation of its vast expanse are poorly understood. The occurrence of two types of leucogranites (the two-mica leucogranites and garnet-bearing leucogranites) identified in the Ailaoshan-Red River (ASRR) shear zone suggests an extension event in the southeastern Tibetan Plateau. The age of these leucogranites could be used to constrain the timing of uplift and southeastward expansion of the plateau. Petrography, geochronology and geochemistry investigations, including Sr–Nd isotope analysis, were conducted on the two-mica leucogranites and garnet-bearing leucogranites from the ASRR shear zone. LA-ICP-MS zircon U–Pb dating indicates that these rocks were emplaced at ~27 ​Ma, implying that the Tibetan Plateau had already achieved maximum uplift prior to the late Oligocene. It subsequently started to expand southeastward as a result of crustal flow. Compared to classic metapelite-derived leucogranites from Himalaya, the two-mica leucogranites show high K2O/Na2O (1.31–1.92), low Rb/Sr, CaO, lower 87Sr/86Sr ratios (0.7089–0.7164) and higher εNd(t) (−8.83 to −3.10). This whole-rock geochemical characteristics likely indicates a mixing source origin, composed predominantly of amphibolite with subordinated metapelite, which is also evidenced by 87Sr/86Sr vs. εNd(t) diagram. However, The garnet-bearing leucogranites with high SiO2 contents (72.25–74.12 ​wt.%) have high initial 87Sr/86Sr ratios (0.7332–0.7535) and low εNd(t) (−16.36 to −18.98), indicating that they are derived from the source comprised of metapelite and results of fluexed muscovite melting under lower crustal level, which is also evidenced by the Rb–Sr–Ba systematics. These leucogranites formed from partial melting of the thickened lower crust, which resulted in the formation of granitic melt that weakened the crust. The weakened crust aided the left-lateral strike-slip movement of the ASRR shear zone, triggering the escape of the Indochina terrane in the southeastern Tibetan Plateau during the late Oligocene. Keywords: Leucogranites, Crustal flow, Southeastward expansion, Ailaoshan-red river shear zone, Tibetan plateau

A coastline is the boundary zone between land and sea, an active zone of human social production activities and an area where the ecology is fragile and easy to change. The traditional method to analyze temporal and spatial changes in the coastline is to extract the coastline through remote sensing, LiDAR, and field sampling and analyze the temporal and spatial changes with statistical data. The coastline extracted by these methods has high spatial and temporal resolution, but it requires remote sensing images and data obtained by other sensors, so it is impossible to extract coastlines from before the emergence of remote sensing technology. This paper improves the coastline generation algorithm. Firstly, a triangulated irregular network is used to generate the preliminary rough coastline, and then, each line segment is optimized with Python language according to the influence range of the place names to further approach the real coastline. The accuracy of the coastline extracted by this method can reach 80% within 500 m, which is of great significance in the mapping and analysis of small- and medium-scale coastlines. This paper analyzes the changes in the coastline of Hainan Island before the founding of China (pre-founding) and in modern times and analyzes the impact of coastal development on coastline change. Through the analysis, it is found that, from before the founding of the People’s Republic of China to the present, the natural coastline of Hainan Island has become shorter, the artificial coastline has become longer, and the coastline generally presents a trend of advancing toward the ocean. This method realizes coastline construction under the condition of missing remote sensing images and puts forward a new way to study historical coastline changes.

The Early Cretaceous Houyaoyu granite porphyries are located in the south margin of the North China Craton. Field observations, petrography, geochronology, major and trace elemental and Sr-Nd isotopic compositions are reported to elucidate the genesis of the Houyaoyu granite porphyries. SIMS zircon U-Pb analyses for the Houyaoyu granite porphyries yield two concordant ages of 133.2±2.3 (2σ) and 131±1.1 (2σ) Ma, respectively. Major and trace elemental compositions indicate that these porphyries are high-K I-type granites with high contents of SiO2, K2O, Rb, U, Pb, low Nb, Ta, Ti, and P. Initial 87Sr/86Sr ratios range from 0.708 3 to 0.709 7, and eNd(t) values range from -9.13 to -12.3, with corresponding two-stage depleted-mantle Nd model ages (T2DM) varying from 1.57 to 1.91 Ga. This suggests that the Houyaoyu granite porphyries were predominantly derived from ancient lower continental crust, with minor involvement of mantle-derived components. On the basis of the tectonic evolution of the Qinling Orogen and geochemical characteristics of the Houyaoyu granite porphyries, it is proposed that they were formed in an extensional tectonic setting related to lithospheric destruction of the North China Craton, and produced Mo and Pb-Zn mineralization in East Qinling Orogen.

Worldwide phosphogenesis during the early Cambrian occurred coevally with localized Rare Earth Element plus Y (REY)-rich phosphorite in Zhijin, South China. Although characteristics of the Zhijin phosphorite have been well constrained, the major factors controlling REY enrichment remain unknown. To address this, the research studied the REY occurrence forms and enrichment mechanisms. Accordingly, carbonate C and O isotopes, micropetrographic, and in situ geochemical analyses of Zhijin phosphorites were conducted. Results show that the phosphates are composed of closely-packed nano to μm-scale apatites, which were spherulitic and short cylindrical, comprising mainly fluorapatites and minor francolites. Element mapping verifies that REYs were hosted in apatites by isomorphous substitution, with minor REY being adsorbed by clay minerals. Further, REY was incorporated into apatite crystals during the early diagenesis according to LaN/SmN vs. LaN/YbN plots. Apatites show Medium REE (MREE)-rich post-Archean Australian shale-normalized distribution patterns, attributed to selective adsorption of MREE by Fe-/Mn oxides/hydroxides or organic matters. Plots of Nd and Ceanom manifest lower sedimentation rates of REY, providing adequate time for REY absorption in the seawater. Excluding secular variations of REEs in the ocean chemistry, we suggest that constrained paleogeography provided a suitable space for REEs entering apatite crystals during early diagenesis. This is possibly the primary cause for the vast REE reserves of Zhijin phosphorite deposit. In addition, redox conditions, temperature, biological activities, and weathering played non-critical roles in REY enrichment in apatites. Our findings can inform on multi-factor constraints of REY-rich marine phosphorites in the early Cambrian and provide a further understanding of REY enrichment in worldwide sedimentary marine phosphorites.

While remote sensing methods have long been used for coastal and desert sand dune studies, few methods have been developed for the automated measurement of dune migration in large dune fields. To overcome a major limitation of an existing method named “pairs of source and target points (PSTP)”, this paper proposes a toe line tracking (TLT) method for the automated measurement of dune migration rate and direction using multi-temporal digital elevation models (DEM) derived from light detection and ranging (LiDAR) data. Based on a few simple parameters, the TLT method automatically extracts the base level of a dune field and toe lines of individual dunes. The toe line polygons derived from two DEMs are processed using logical operators and other spatial analysis methods implemented in the Python programming language in a geographic information system. By generating thousands of random sampling points along source toe lines, dune migration distances and directions are calculated and saved with the sampling point feature class. The application of the TLT method was demonstrated using multi-temporal LiDAR-derived DEMs for a 9 km by 2.4 km area in the White Sands Dune Field in New Mexico (USA). Dune migration distances and directions for three periods (24 January 2009–26 September 2009, 26 September 2009–6 June 2010, and 24 January 2009–6 January 2010) were calculated. Sensitivity analyses were carried out using different window sizes and toe heights. The results suggest that both PSTP and TLT produce similar sand dune migration rates and directions, but TLT is a more generic method that works for dunes with or without slipfaces that reach the angle of repose.

The Pulang porphyry copper deposit (PCD), one of the main potential areas for copper resource exploration in China, exhibits typical porphyry alteration zoning. However, further investigation of the indicative significance of alteration minerals, additional insight into metallogenic characteristics, and prospecting guidelines continue to be challenging. In this study, ASTER and WorldView-3 data were used to map hydrothermal alteration minerals by employing band ratios, principal component analysis, and spectrum-area techniques; and subsequently, the indication significance of alteration minerals was studied in-depth. The following new insights into the metallogenic structure and spatial distribution of alteration zoning in Pulang PCD were obtained and verified. (1) A new NE trending normal fault, passing through the northeast of Pulang PCD, was discovered. (2) Two mineralization alteration centers, exhibiting alteration zoning characteristics of potassic-silicified, phyllic, and propylitic zones from the inside to the outside, were observed on both sides of the fault. (3) At the junction of the redivided potassic-silicification and phyllic zones, favorable prospecting potential areas were delineated. This study shows that the spectral/multi-sensor satellite data are valuable and cost-effective tools for the preliminary stages of porphyry copper exploration in inaccessible and remote areas around the world.

Identifying alteration minerals of porphyry Cu deposits by using multispectral remote sensing data is a significant approach for ore prospecting. However, obtaining refined alteration information related to a porphyry Cu system is still challenging, especially in an area with complex geological background. In this study, the effectiveness of spectroscopic techniques for mapping alteration minerals associated with the Pulang porphyry copper deposit, SW China, which is located in high altitude and with tough terrain, were discussed by using ASTER and WorldView-3 data. The method of Principal Component Analysis (PCA) + Spectrum-Area (S-A) was developed to enhance the remote sensing information extraction of the alteration zones with quartz, sericite, chlorite and epidote. The results suggested that the extraction accuracy of porphyry alteration minerals based on WorldView-3 data with the method of PCA + S-A is significantly improved comparing with that of ASTER data. Using the method, we identified a new alteration zone caused by sericite anomalies in the Pulang deposit, which was afterward confirmed by field investigation. Hence, the PCA + S-A method based on WorldView-3 data is an effective approach for mapping alteration zones and ore prospecting in the porphyry copper system.

The recently discovered Guanfang large W deposit, in Yunnan Province, southwest China, is located in the Diandongnan thrust-nappe fold belt in the western part of the Cathaysia Block. The orebodies occur at the contacts between the Suozuodi granite and Middle Cambrian marbles. LA-ICP-MS zircon U Pb dating of the ore-bearing Suozuodi granite yields a crystallization age of 91.6 ± 1.0 Ma (MSWD = 0.56). An isochron age of 91.6 ± 1.3 Ma (MSWD = 0.24) was obtained by Re Os dationg of five molybdenite samples separated from sulfide-bearing ores. Scheelite at the Guanfang deposit is characterized by broad rangs of Pb isotopic ratios ( 207Pb/204Pb = 15.568 to 15.735, 206Pb/204Pb = 17.912 to 18.390, 208Pb/204Pb = 38.491 to 38.730) and high initial 87 Sr/86 Sr ratios (Isr = 0.7118 to 0.7140), which consistent with the isotopic characteristics of the Suozuodi granite. Pb and Sr isotopic results indicate that the ore-forming materials were derived from a crustal source, without addition of mantle materials. The Guanfang tungsten deposit was formed in a syn -collision tectonic setting during the late stage of the Yanshanian tectonism.

Remote sensing has been widely used to interpret hydrothermal alteration zones and it can support the geological field mapping, which is very useful for mineral exploration in inaccessible regions. However, the alteration information in covered terrains is usually not strong enough to be detected using traditional remote sensing methods, so how to efficiently detect subtle alteration information remains a challenging task. In this study, the multifractal theory-based Spectrum-Area (S-A) method is used for the processing of remote sensing data and the new method of “Principal Component Analysis (PCA) + S-A” is proposed as a tool to interpret hydrothermal alteration beneath covered areas. In order to test the efficiency of this method, the “PCA + S-A” method was compared with the traditionally used PCA method based on Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data. The Wuliang Mountain in the Yunnan Province of SW China, a rugged terrain with high altitudes and dense vegetation coverage, was selected as a case study to detect information on chlorite, epidote, biotite, and muscovite alteration, respectively. The following field survey and petrographic studies reveal that: (1) the average detection accuracy of the “PCA + S-A” method is 90.80%, 9.34% higher than that of the PCA method; (2) in the covered areas where the traditional PCA method cannot detect any subtle hydrothermal alteration, the “PCA + S-A” method can be successfully applied; and (3) in those areas where the fractional vegetation cover (FVC) is greater than 0.8, the detection of subtle hydrothermal alteration using the proposed method is inefficient, which requires further studies.

Metamorphic rocks have scientific significance for parsing the evolutionary process of an orogenic belt. The Wuliangshan area is a very complex region of metamorphism, where it is nearly impossible to conduct conventional geological investigation because of the extremely rugged topography and difficult travel conditions. Previous research on the area’s metamorphic rocks is limited. There are two metamorphic belts, the Yunling-Jinghong and Wuliangshan metamorphic belts, identified by means of traditional field survey. To better identify the metamorphic rocks of the Wuliangshan area, this study adopted the principal component analysis (PCA) and spectrum-area (S-A) methods, using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data, to extract the anomalies of diagnostic metamorphic minerals in metamorphic rocks, such as actinolite, chlorite, epidote, biotite, muscovite, hornblende, andalusite, staurolite, cordierite, and sillimanite. The methods are based on the principle that the metamorphic degree is reflected by the diagnostic metamorphic minerals. Profile investigation and petrographic analysis show that the identification accuracy of the diagnostic metamorphic minerals reached 85.65%. Seven concentrations of metamorphic rocks were delineated based on the extracted metamorphic mineral anomalies. Compared with previous study results, this study showed that there are metamorphic rocks in defined Regions 1, 2, 3, 4 and 6, which are consistent with existing data; whereas in Regions 5 and 7, there is new information regarding the existence of metamorphic rocks, which may offer new clues about the formation of this area through additional studies. The results of this study not only reveal detailed information for geological survey of the Wuliangshan area but also provide useful methods for future surveys.

For high concrete face rockfill dam (CFRD) based on deep overburden layers, the interaction between dam body and foundation results in the dynamic response and permanent deformation during the earthquake. Using the 3D non-linear dynamic FEM and “Dam-Reservoir” dynamic coupling system, the dynamic response of high concrete face rockfill dam was analyzed with emphasis on the distribution characters of dynamic displacement, absolute acceleration and dynamic stress. Besides, the seismic liquefaction and seismic settlement of the overburden layers was also discussed. It is shown that the seismic subsidence rate is small and the earthquake liquefaction does not happen under the earthquake with intensity of VII degree.

Water temperature affects not only the water quality and ecological balance of the reservoir, but the temperature and stress field distribution of the high arch dam during water storage and operation management. During low water storage and initial operation, the concrete in reservoirs over 100 m deep in particular can easily crack or expand because of low temperature reservoir water. This paper studies the water temperature distribution law of the reservoir during initial storage by establishing a three-dimensional fluid dynamics model. Based on this, this paper explores the three-dimensional temperature field and stress field of the dam body during the storage period, the causes of cracking, and stress distribution in key parts of the arch dam.

In recent years, researchers identify the complete softening curve of concrete materials by employing inverse analysis method. The inverse analysis method based on fracture experiments of concrete is numerical simulations by using discrete approach of non-linear fracture mechanics. First, a softening curve is assumed and the load–displacement curve obtained by the numerical simulation is compared to the one determined experimentally by fracture experiment of concrete. By updating the assumed softening curve, the numerical results optimally fit the measured ones. When the best fit of the numerical and the experimental results is obtained, the assumed softening curve is viewed as the one for characterization of the material behavior. Load-crack mouth opening displacement curve (PCMOD curve) is an important measured curve which characterizes fracture property of concrete in fracture experiment. For each group of fracture experiment specimens, there are three companion specimens tested in the group. The emphasis of this paper is as follows: Developed a processing program for the original test data which length is up to 30000~300000 lines for each specimen. The program can filter test data scattered far from the P-CMOD curve and remove the effect of fluctuation in the measurement of fracture experiment. A new test data processing method for fracture experiment of concrete was proposed based on crack propagation process of concrete materials. Thus a representative P-CMOD curve which characterizes the fracture property of the companion specimens for each concrete specimen group is achieved by averaging the above-mentioned test results of three companion specimens. Since the number of data points used in optimal fitting of inverse analysis have an effect on the computer running time observably, the minimum number of data points adequately representing P-CMOD curve is desirable. The minimum of data points were extracted from the averaged data for the companion specimens by an optimization procedure. This paper employed the proposed method to analyze the original test data of different sizes of wedge-splitting ∗ Corresponding author, e-mail: zhaozhifang7@126.com © Springer Science+Business Media B.V. 2009 Y. Yuan, J.Z. Cui and H. Mang (eds.), Computational Structural Engineering, 1239–1247. specimens made of dam concrete. The representative P-CMOD curves were obtained for companion specimens of different fracture specimen groups. The obtained representative P-CMOD curves were prepared for an inverse analysis to find the softening curves of dam concrete and were employed to investigate the fracture property of dam concrete.