The Narusongduo Pb-Zn deposit is located at the northern boundary of the Luobadui-Milashan fault zone (LMF) in central Tibet and is spatially associated with the Linzizong volcanic succession (LVS). Our study indicates that the regional structural setting was formed by two-stage tectonic events. The first stage, spanning from the late Mesozoic to early Paleocene, is characterized by significant N-S crustal shortening associated with the Cordilleran-type orogeny along the Gangdese arc. The region's Paleozoic-Mesozoic metasedimentary rocks were penetratively strained. Locally deformation was largely partitioned along the LMF. During the second stage (ca. 66–55 Ma), the area was affected by extensive multi-stage Linzizong volcanism, including caldera formation, as well as a coaxial N-S propagative deformation with a distinctive lower shortening rate. We recognized two types of mineralization, both were formed during the second stage. The first type of mineralization (orebody III) is governed by fractures within the extensively deformed Paleozoic carbonate rocks at the LMF's footwall. The overlying LVS, however, includes discrete but numerous mineralized sections. The terminal splays of the ore shoots typify the products of hydraulic fracturing. We propose that the propagative compressive deformation drained fluid reservoirs at depth to higher levels via the "Fault valve" effect. Episodic fluid influxes and mineral deposition formed the time-integrated mineralization. The second type of mineralization (orebody I) is hosted in the LVS in a number of breccia pipes and dykes that were controlled by the structural weaknesses generated by the intersection of the radial and ring fractures. Mineralization occurs as veinlets in the matrix and clasts inside the breccias, which are characterized by multi-stage brittle cracking, fluid injection and mineral precipitation. It is interpreted that the multi-stage magmatism (ca. 66–55 Ma) triggered repeated hydrothermal activities and incremental mineralization within the ore-bearing breccia bodies.
The Tibetan Plateau geographically contains internal and external drainage areas based on the distributions of river flows and catchments.The internal and external drainage areas display similar highelevations, while their topographic reliefs are not comparable; the former shows a large low-relief surface, whereas the latter is characterized by relatively high relief.The eastern Lhasa terrane is a key tectonic component of the Tibetan Plateau.It is characterized by high topography and relief, but the thermal history of its basement remains relatively poorly constrained.In this study we report new apatite fission track data from the eastern part of the central Lhasa terrane to constrain the thermo-tectonic evolution of the external drainage area in the southern Tibetan Plateau.Twenty-one new AFT ages and associated thermal history models reveal that the basement underlying the external drainage area in southern Tibet experienced three main phases of rapid cooling in the Cenozoic.The Paleocene-early Eocene ($60-48 Ma) cooling was likely induced by crustal shortening and associated rock exhumation, due to accelerated northward subduction of the NeoTethys oceanic lithosphere.A subsequent cooling pulse lasted from the late Eocene to early Oligocene ($40-28 Ma), possibly due to the thickening and consequential erosion of the Lhasa lithosphere resulted from the continuous northward indentation of the India plate into Eurasia.The most recent rapid cooling event occurred in the middle Miocene-early Pliocene ($16-4 Ma), likely induced by accelerated incision of the Lhasa River and local thrust faulting.Our AFT ages and published low-temperature thermochronological data reveal that the external drainage area experienced younger cooling events compared with the internal drainage area, and that the associated differentiated topographic evolution initiated at ca. 30 Ma.The contributing factors for the formation of the high-relief topography mainly contain active surface uplift, fault activity, and the enhanced incision of the Yarlung River.
The content of the dispersed elements is very low in the nature. They are existence with dispersed state. They are seldom to form independent minerals and deposits. Therefore,it has important theoretical and practical significance to research the associated dispersed elements in deposits. This work researched the typical lead-zinc deposits in the eastern edge of Kangdian Axis (Tianbaoshan,Daliangzi and Huize).Used on the observation of the common microscope and the means of electron microprobe analysis and ICP-MS analysis,we analyzed the occurrence status and enrichment law of dispersed elements of Cd,Ge and Ga,summed up the distribution rule of dispersed elements of Cd,Ge and Ga. From west to east,that is,from Tianbaoshan to Daliangzi to Huize,the content of the dispersed elements of Cd,Ge and Ga have alternation law of enrich Cd and Ga to enrich Cd to enrich Ge.
In the Eopaleozoic,Pan Xi region lied on the south of the Yang Zi plate,on the passive margin close to the north of the SN Kun Ming-Zhao Jue continental shelf faulted depression line.The field belt standed on the favorable structure magma hydrothermal fluid active triangle structural knot which was formed of XiaoJiang fault,PuGe-NingNan fault and HuiLi-NingNan-JinYang fault.YinChangGou-QiLuoGou bed located at the west of the QiLuoGou plunging anticline close to the rachis,the horizon is carbonatite of the lamp shadow group upper segment of Sinian Period,it'soverlying formation is Camb.cambrian Qun Zhu Si group argillaceous sandstone.Main controlled massive fault of the lease is NNW and the tension fault of the peri north and south.
Located in the Namling Country of Tibet,the Pusangguo copper polymetallic deposit is a skarn-hydrothermal vein type deposit and lies in the eastern part of the Gangdise belt.The ore mineral compositions and the modes of occurrence of Co-Ni were systematically studied in this paper.The ores are made up of some complex medium-low temperature hydrothermal minerals,such as chalcopyrite,pyrite,galena,marmatite,pyrrhotite and covellite.The modes of occurrence of Co-Ni revealed by means of microscope and scanning electron microprobe indicate that Co-Ni are mainly present as cobaltite(Co 17.87%,Ni 12.66%);and are also scattered in ferrous sulfides,such as chalcopyrite(Co 0.04%,Ni 0.08%),pyrite(Co 0.40%,Ni 0.20%),sphalerite(Co 0.14%,Ni 0.06%),and pyrrhotite(Co 0.79%,Ni 0.18%),in which Co-Ni exist in the form of isomorphous replacement of Fe.The results indicate that there exists a new type of mineralization in the Gangdise belt,and this discovery supplies important information for further exploration.
Abstract The southeastern (SE) Tibetan Plateau (Yunnan) is characterized by low‐relief uplands that were deeply incised by large rivers. The thermal history of basement rocks in this region remains poorly investigated, while this data is needed to elucidate the complex relationship between tectonics and climate in shaping the surface. To better understand its thermo‐tectonic evolution, we carried out apatite fission track thermochronology on 31 samples collected from a large area that covers different tectonic units, including a vertical profile in the middle Mekong River valley; additional zircon LA‐ICP‐MS U‐Pb dating was performed on four basement rocks. Our results confirm that a large portion of Mesozoic crystalline rocks constitute the basement of the SE Tibetan Plateau. Inverse thermal history modeling of fission track data reveal extensive late Oligocene to Miocene rapid basement cooling and exhumation episodes from both inside and outside the active zones (i.e., ductile shear zone and river valley). These thermal events were coincident with the activities of large‐scale strike‐slip faults that dominate the structural framework. Combined with the published data, we propose that widespread crustal shortening and thickening took place in the SE Tibetan Plateau during the Oligocene‐Miocene in the context of a compressive tectonic regime. Low‐temperature thermochronological data reveal that both tectonic forcing and climate‐driven erosion have played important roles in exhuming the basement rocks in the region. It is also deduced that the present‐day relatively low‐elevation landscape of the Yunnan area resulted from complex interaction between regional tectonic activity and surficial erosion since the late Oligocene.
Based on related fundamental data,this paper analyzed the characteristics of nonferrous metal mineral resources of Sichuan province ;Combining to the reality of the nonferrous metals industry in Sichuan and the actuality of the nonferrous metals industry in China,the paper put forward some countermeasures about sustainable utilization of nonferrous metals mineral resources in Sichuan.It is pointed out that nonferrous metals mineral resources of Sichuan have the following main characteristics: Firstly,they almost comprise all kinds of nonferrous metals;Secondly,their reserves are comparatively abundance;Thirdly,their grades are both fine and inferior;Fourthly,the space distribution of their deposits is relatively centralized;Fifthly,their deposits are few large scale ones and many small scale ones,and the average scale of their deposits is relatively small;Sixthly,their tenors are both rich and poor,and their deposits are little rich ones and many poor ones;Seventhly,associate and commensal useful components are abundant in them.It is put forward that countermeasures,which are about sustainable utilization of nonferrous metals mineral resources in Sichuan,are following: Firstly,economizing resources,laying equal stress on the resources exploiture and the resources protection;Secondly,bringing forth new ideas in science and technology,activating bad resources;Thirdly,comprehensively and circularly utilizing resources,raising the extraction ratio of mineral resources;Fourthly,putting geologic examination in advance,searching nonferrous metals mineral resources which are lack and high grade or in deep and periphery of old mines;Fifthly,paying equal attention to the resources exploiture and the entironment protection,developing the green mineral industry;Sixthly,adjusting taxes and fees,lightening the mine enterprise burden,strengthening the mine enterprise functions for ore prospecting and environments constucting,and so on.
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