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941.
WUHongling WANGWei 《大地构造与成矿学(英文版)》2003,27(1):120-129
This paper discusses some mechanical concepts that have been largely applied to structural geology and tectonics, and addresses the problems and misunderstandings in use of these mechanical terms. The purpose is to stimulate the interests for structural geologists in using the mechanical principles and methods correctly to solve the geodynamic problems. 相似文献
942.
LIUZhifei WANGChengshan AlainTRENTESAUX ZHAOXixi YIHaisheng HUXiumian JINWei 《《地质学报》英文版》2003,77(4):504-513
Sedimentological, cyclic-stratigraphic, paleomagnetic, and clay-mineralogical studies on the early Oligocene Yaxicuo Group in the Hoh Xil Basin, the largest Cenozoic sedimentary basin in the hinterland of the Tibetan Plateau, provide abundant information of paleoclimate changes. A 350-m thick section in the middle-lower Yaxicuo Group was analyzed to reveal the climatic history that occurred in the Hoh Xil region during the early Oligocene interval 31.30-30.35 Ma, dated with the paleomagnetic chronostratigraphy. The results indicate that add and cold climate dominated the Hoh Xil region during the early Oligocene in general, being related to the global cooling and drying events that occurred in the earliest Oligocene. Within this period, relatively warm and wet climate accompanied by strong tectonic activity occurred in the 31.05-30.75 Ma interval; while add and cold climate and relatively inactive tectonics occurred in the 31.30-31.05 and 30.75-30.35 Ma intervals. Furthermore, spectral analyses of high-temporal resolution paleoclimatic records show orbital periods including eccentricity, obliquity, and precession. It is concluded that paleoclimate changes during the early Oligocene in the Hoh Xil region were forced by both tectonic activity and orbital periods. 相似文献
943.
Zuoheng Zhang Jingwen Mao Jianmin Yang Zhiliang Wang Zhaochong Zhang 《Resource Geology》2003,53(2):101-114
Abstract. The Ta'ergou tungsten deposit in Gansu province, northwestern China, is located in the western part of the North Qilian Caledonian orogen, and consists of scheelite skarn bodies and wolframite quartz veins. The tungsten‐bearing skarn developed by the replacement of carbonate layers intercalated in the Precambrian schist and amphibolite whereas wolframite‐quartz ore veins developed along a group of fractures that cut through horizontal skarns. The Ta'ergou tungsten deposit is genetically related to the Caledonian Yeniutan granodiorite intrusion and occurs ca. 500 m wide in the exo‐contact zone 300 ~ 500 m apart from the intrusion. The granodiorite displays a lower grade of differentiation, low content of SiO2 and high contents of mafic components. There are three types of fluid inclusions in the wolframite‐quartz vein systems, i. e. aqueous, CO2‐H2O and CO2‐rich. The homogenization temperature of aqueous inclusion ranges from 140 to 380d?C and their salinities from 6.4 to 17.4 equivalent wt% NaCl. Laser Raman spectroscopy shows that the inclusions contain a relatively high content of CO2. The δ34S values of skarn type sulfides range from +8.1 to +12.7 per mil and those of quartz vein sulfides from +9.3 to +14.9 per mil, similar to sulfides of the granodiorite with from +6.0 to +11.7 per mil. The δ18O values of quartz are between +10.5 and +13.3 per mil and those of wolframite between +3.4 and +5.1 per mil. The δ18O water values of ore forming fluids range from +0.6 to +6.4 per mil and suggest the mixture of magmatic fluids with meteoric water formed the ore‐forming fluids. It has been proved that Precambrian strata in the west sector of North Qilian region are enriched in tungsten. We propose the strata were remelted to be tungsten‐granitoid during subduction. The polymetallic tungsten was gradually accumulated into the roof pendants of the granite intrusion by fractional crystallization and then was deposited by hydrothermal fluids during metasomatism and infilling along fractures. On the other hand, the granite intrusion also acted as “heating machine” to make hydrothermal fluids leach out the metals from Precambrian strata and these metals joined the ore‐forming hydrothermal system. 相似文献
944.
Abstract. Skeletal sphalerite with stellar, cruciform and snowflake-like (or cauliflower-like) shapes included in pyrite is widely found in the Dajing tin-polymetallic deposit. It occurs only in chalcopyrite-pyrite mineralization stage. The compositions of all sphalerites in the chalcopyrite-pyrite stage are characterized by high Cu content (3.9 - 7.0 wt% with a mean of 5.4 wt%), while the skeletal crystal sphalerite has higher zinc and cadmium contents, and lower copper and iron contents, compared with other sphalerites of the same stage. The skeletal crystal sphalerite in pyrite is possibly generated by exsolution. 相似文献
945.
Origin and tectonic significance of a Mesozoic multi-layer over-thrust system within the Yangtze Block (South China) 总被引:21,自引:0,他引:21
Dan-Ping Yan Mei-Fu Zhou Hong-Lin Song Xin-Wen Wang John Malpas 《Tectonophysics》2003,361(3-4):239-254
In the Yangtze Block (South China), a well-developed Mesozoic thrust system extends through the Xuefeng and Wuling mountains in the southeast to the Sichuan basin in the northwest. The system comprises both thin- and thick-skinned thrust units separated by a boundary detachment fault, the Dayin fault. To the northwest, the thin-skinned belt is characterized by either chevron anticlines and box synclines to the northwest or chevron synclines to the southeast. The former structural style displays narrow exposures for the cores of anticlines and wider exposures for the cores of synclines. Thrust detachments occur along Silurian (Fs) and Lower Cambrian (Fc) strata and are dominantly associated with the anticlines. To the southeast, this style of deformation passes gradually into one characterized by chevron synclines with associated principal detachment faults along Silurian (Fs), Cambrian (Fc) and Lower Sinian (Fz) strata. There are, however, numerous secondary back thrusts. Therefore, the thin-skinned belt is like the Valley and Ridge Province of the North American Applachian Mountains. The thick-skinned belt structurally overlies the thin-skinned belt and is characterized by a number of klippen including the Xuefeng and Wuling nappes. It is thus comparable to the Blue Ridge Province of Appalachia.The structural pattern of this thrust system in South China can be explained by a model involving detachment faulting along various stratigraphic layers at different stages of its evolution. The system was developed through a northwest stepwise progression of deformation with the earliest delamination along Lower Sinian strata (Fz). Analyses of balanced geological cross-sections yield about 18.1–21% (total 88 km) shortening for the thin-skinned unit and at least this amount of shortening for the thick-skinned unit. The compressional deformation from southeast to northwest during Late Jurassic to Cretaceous time occurred after the westward progressive collision of the Yangtze Block with the North China Block and suggests that the orogenic event was intracontinental in nature. 相似文献
946.
Cretaceous deformation history of the middle Tan-Lu fault zone in Shandong Province, eastern China 总被引:13,自引:0,他引:13
Based on field analysis of fault-slip data from different rock units of the Cretaceous basins along the middle part of the Tan-Lu fault zone (Shandong Province, eastern China), we document polyphase tectonic stress fields and address the changes in sense of motion of the Tan-Lu fault zone during the Cretaceous. The Cretaceous deformation history of the Tan-Lu fault zone can be divided into four main stages. The first stage, during the earliest Cretaceous, was dominated by N-S extension responsible for the formation of the Jiaolai basin. We interpret this extension to be related to dextral strike-slip pull-apart opening guided by the Tan-Lu fault zone. The second stage, during the middle Early Cretaceous, was overwhelmingly rift-dominated and characterized by widespread silicic to intermediate volcanism, normal faulting and basin subsidence. It was at this stage that the Tan-Lu-parallel Yi-Shu Rift was initiated by E-W to WNW-ESE extension. The tectonic regime then changed during the late Early Cretaceous to NW-SE-oriented transpression, causing inversion of the Early Cretaceous rift basin and sinistral slip along the Tan-Lu fault zone. During the Late Cretaceous, dextral activation of the Tan-Lu fault zone resulted in pull-apart opening of the Zhucheng basin, which was subsequently deformed by NE-SW compression. This deformation chronology of the Tan-Lu fault zone and the associated Cretaceous basins allow us to constrain the regional kinematic models as related to subduction along the eastern margin of Asia, or related to collision in the Tibet region. 相似文献
947.
WangShicheng YeShuisheng ZhouDongdai 《中国地质大学学报(英文版)》2003,14(3):207-214
Metallogenic prognosis of synthetic information uses the geological body and the miaeral resource body as a statistical unit to interpret synthetically the information of geology, geophysics, geo-chemistry and remote sensing from the evolution of geology and puts all the information into one entire system by drawing up digitalized interpretation maps of the synthetic information. On such basis, differ-ent grades and types of mineral resource prospecting models and predictive models of synthetic informa-tion can be established. Hence, a new integrated prediction system will be formed of metallogenic prog-nosis (qualitative prediction), mineral resources statistic prediction (determining targets) and mlaeral resources prediction (determining resources amount). 相似文献
948.
During the whole 20th century in China, especially the latest 50 years, we have gotten much geological information about geological mapping, geophysics, geochemistry, mineral exploration,remote sensing, environmental geology, hydrogeology, engineering geology and oceanic geology etc. by our geologists and explorers. All the information has been accmnulated and can be used as a dcision-making foundation for the future plan of geological survey. The spatial database of geological survey ex-tents has been established by using computer technology. The database contained all kinds of exploration sections and collected about 160 000 records in this database. This paper introduces the data construc-tion ,contents and applying systemof this database, and trys to let people know what kinds of geological survey were finished, when the exploration were carried out, and how and where you can get this infor-mation. 相似文献
949.
ChenJianguo ChenZhijun WangQuanming FangYiping 《中国地质大学学报(英文版)》2003,14(3):250-256
The spatial database management system of China geological survey extent is a social service system. Its aim is to help the government and the whole social public to expediently use the spatial database, such as querying, indexing, mapping and product outputting. The management system has been developed based on MAPGIS6. x SDK and Visual C , considering the spatial database contents and structure and the requirements of users. This paper introduces the software structure, the data flow chart and some key techniques of software development. 相似文献
950.