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High and Low Temperature Gold Mineralizations in the Fe–Cu–Zn Sulfide Deposits of Corchia Ophiolite, Northern Italian Apennine  [PDF]
Zaccarini Federica,Giorgio Garuti
Minerals , 2013, DOI: 10.3390/min3010082
Abstract: Gold has been found in the Cyprus-type volcanogenic massive sulfide ore (VMS) deposits of Corchia ophiolite (Parma province, Italy) in the Cantiere Donnini, Speranza and Pozzo mining sites. At Cantiere Donnini and Speranza, the mineralization occurs at the contact between pillow lava and sedimentary rocks. The Pozzo mineralization is hosted by a serpentinite. Concentrations of gold up to 3070 ppb have been reported for the Cantiere Donnini and up to 6295 ppb in the Pozzo mine. According to the field relationships, gold composition, mineralogical assemblage and sulfur isotope data, we can conclude that two different types of gold mineralization have been recognized in the Corchia ophiolite: (1) formed at low temperature in submarine environment (Cantiere Donnini and Speranza) and (2) formed at high temperature in the oceanic mantle (Pozzo) by segregation of an immiscible sulfide liquid.
Geological setting and structural styles of Volcanic Massive Sulfide deposits in the northern Apennines (Italy): evidence for sea floor and sub-sea floor hydrothermal activity in unconventional ophiolites of the Mesozoic Tethys
Garuti, Giorgio;Bartoli, Omar;Scacchetti, Maurizio;Zaccarini, Federica;
Boletín de la Sociedad Geológica Mexicana , 2008,
Abstract: this paper is an overview of the geological setting and structural styles of cu-sulfide deposits of the vms-type, associated with tethyan ophiolites (the ligurides) in the northern apennines (italy). the italian deposits represent a rare example of vms associated with both the mantle-peridotite basement and the overlaying volcanic pile, within a single ophiolite sequence. this peculiar feature is due to the particular geodynamic evolution of the mesozoic ligurian ocean that allowed the upper mantle to be exposed on the seafloor for a long period before the outflow of morb-type lava and the deposition of pelagic sediments (cherts, palombini shales and calpionella limestones). middle to upper jurassic uprising of the basaltic magma initially provided the heath source for convective circulation of hydrothermal fluids through the overlaying mantle section, giving rise to sulfide deposition in crosscutting stockwork-veins and seafloor-stratiform ore bodies within the serpentinized mantle peridotite and the serpentinite breccia formed by submarine erosion of the upper mantle. the setting and structure of vms associated with the volcanic pile indicate that hydrothermal activity continued during and after the eruption of pillow basalts at the ocean floor, forming stockwork veins and conformable stratabound ore bodies within the basalt unit. furthermore, hydrothermal activity formed seafloor-stratiform deposits, at the top of the volcanic pile, covered with a thick horizon of cherts containing exhalative deposits of mn.
Electrical Structure of Sea-Floor Hydrothermal Sulfide Deposits

Xi Zhenzhu
, Li Ruixue, Song Gang, Zhou Sheng

地球科学(中国地质大学学报) , 2016, DOI: 10.3799/dqkx.2016.110
Abstract: 深海热液金属硫化物矿位于水深数千米的大洋洋底,其形态、规模及电性参数难为人知,迄今尚未有由实测数据推导其电性结构的研究.依托于“大洋一号”,在大西洋洋中脊、西南印度洋洋中脊实施了多次深海热液金属硫化物矿探测试验,实地采集热液金属硫化物矿瞬变电磁响应数据,并对试验数据进行反演分析.分析表明:大西洋TAG(trans-Atlantic geotraverse)热液区及西南印度洋49°4′E,37°5′S热液区内,深海热液金属硫化物矿形似生长于洋壳内的“蘑菇”,矿体呈透镜状或似层状结构,分布于热液喷口的卤水池内,电阻率约为0.1Ω·m,规模为50~250 m,厚度范围为20~50 m;热液烟囱直径为10~50 m,周围岩石发生热液蚀变,蚀变岩石电阻率在0.2~0.5 Ω·m,以热液通道为中心呈圈层状变化.依据深海热液金属硫化物矿的形态特征及电性参数,矿体的电性结构模型可简化为T型异常体.
The deep sea hydrothermal metallic deposits are located on seafloor at depth about several kilometers, and it is difficult to determine their shape, scale and electrical parameters, and the electrical structure based on field data remains unknown. Using research vessel “DaYang-Ⅰ”, several detection tests were implemented at Atlantic ridge and Southwest Indian ridge, and the electromagnetic response data of deep-sea hydrothermal metallic sulfide deposits have been observed and analyzed. The analysis show that in the Atlantic TAG (trans-Atlantic geotraverse) hydrothermal area and Southwest Indian Ocean 49°4′E, 37°5′S hydrothermal area, deep-sea hydrothermal metallic sulfide deposits are like‘mushroom’ in the oceanic crust, located in the brine pool around the hydrothermal vents with lenticular structure or stratoid structure, the resistivity is about 0.1 Ω·m, the scale changes from 50 to 250 m, and the thickness is from 20 to 50 m. The diameter of hydrothermal channel ranges from 10 to 50 m,and hydrothermal alternation took place within and outside the hydrothermal channel. The resistivity of the alternation rocks is in the range of 0.2 to 0.5 Ω·m, and concentrically changes around the hydrothermal channel. Based on the shape and electrical parameters of hydrothermal metallic sulfide deposits, the ore body can be simplified as a T-shaped target for electrical structure model
REE characteristics of Cu-Ni sulfide deposits in the Hami area, Xinjiang

WANG YuWang,WANG JingBin,WANG Lijuan,FANG TongHuiBeijing Institute of Geology for Mineral Resources,Beijing,ChinaKey Laboratory of Mineral Resources Research,Institute of Geology,Geophysics,Chinese Academy of Sciences,Beijing,China,

岩石学报 , 2004,
Abstract: On the base of study on the REE geochemistry of ore minerals and host rocks of typical deposits from Huangshan Cu-Ni metallogenic belt, Xinjiang, it was discovered that the host mafic-ultramafic rocks of the Cu-Ni sulfide deposits occurred in orogen are characterized by water-richment. Some REE pattern of sulfides shows particular " triplex curve" model, which suggests that due to coexistence of multiple liquid phase ( fluid and melt) , the sulfide melt possibly contained a lot of hydrothermal fluid and increasingly derived to gas and liquid-rich ore-forming fluid after the master metallogenic epoch (magmatic segregation stage). REE characteristics of the deposits in this area are quite different from thos of the Cu-Ni deposit occurred in cratonic margin, and the reason of hydrothermal fluid joining in mineralization might be owing to water-rich of ore-bearing rockbody that related to delamination and melting of water-rich oceanic crust in post-collision stage.
Application of concentration-volume fractal method in induced polarization and resistivity data interpretation for Cu-Mo porphyry deposits exploration, case study: Nowchun Cu-Mo deposit, SE Iran
L. Daneshvar Saein, I. Rasa, N. Rashidnejad Omran, P. Moarefvand,P. Afzal
Nonlinear Processes in Geophysics (NPG) , 2012,
Abstract: The aim of this study is the utilization of the concentration-volume (C-V) fractal method based on geoelectrical data including induced polarization (IP) and resistivity (RS) in targeting areas hosting different sulfidic mineralization zones in Nowchun Cu-Mo porphyry deposit, SE Iran. The C-V fractal model employed in this research in order to separate high and moderate sulfidic zones from low sulfidic zone and barren wall rocks in the deposit is corresponding to chargeability and resistivity. Results obtained from the C-V method indicate that there is a positive correlation between subsurface mineralization and sulfide mineralized zones; additionally, use of the C-V method based on geophysical data is recognized as an accurate approach for delineation of various mineralization zones in the depth for optimization of mineral exploration operation, particularly in porphyry deposits.
Electrical Resistivity Imaging (ERI) of Slope Deposits and Structures in Some Parts of Eastern Dahomey Basin  [PDF]
P.R. Ikhane,K.O. Omosanya,A.A. Akinmosin,A.B. Odugbesan
Journal of Applied Sciences , 2012,
Abstract: Outcrop analog are important tools for better understanding of large scale seismic features such as slope deposits and structures. Sedimentary exposures at Ijebu Omu, Itele and Ijebu Ife, all within the eastern part of Dahomey basin, Southwest Nigeria were imaged using Electrical geophysical method with the aim of reconstructing the geological history of the area and providing a basis for understanding larger scale structures. The Electrical Resistivity Imaging was done using a Wenner array configuration with a -spacing of multiples of 5 m; the result was iterated using RES2DINV. Both smooth and robust inversion of the apparent resistivity data was carried out. From the geologic models, dimension of structures were determined and three dimensional evolutionary diagrams were drawn. Six (6) geo-electric facies were identified from the three locations; they include clay, resistive clay, sand, sandstone, compacted sandstone and conglomerate with average resistivity value of ~16.27 Ωm, ~58 Ωm, ~392 Ωm, ~1264 Ωm, ~2196 Ωm and ~4633 Ωm, respectively. The meandered sandy bodied channels identified at Ijebu Omu have aspect ratios of ~4.00, ~1.37, ~2.59 and ~3.13, respectively, those at Itele ~5.9 and ~7.30 and the one at Ijebu-Ife ~3.19; meanwhile ~5 m, ~8 m and ~8.5 m thick clastic dykes were seen at Itele. Due to their high aspect ratios, the sinuosity of the channels in the study area is very high, thus the conclusion that they are meandering. The clastic dykes at Itele were formed as a result of overburden pressure and undercompaction typical of soft sediment deformation or syn-sedimentary deformation.
Application of Orthogonal Functions Fitting to the Exploration of Massive Sulfide Deposits in Ashele,Xinjiang

ZHANG Yu-cai,ZHAO Chang-long,

地球学报 , 1995,
Abstract: The large copper-rich deposit in exploring in Ashele,Xinjiang,is a typical vulcanogenic massivesulfide deposit.Thick, large and lenticular orebodics exhibit the stratabound character,and there isappreciable difference in density between orebodies and country rocks.Ground geophysical methods,mainly the gravity method,have been proved to be the most effective methods for the reconnaissanceof hidden massive sulfide deposits,But the Ashele ore district is characterized by complex geologicalstructures. As the gravity effects due to gravitational bodies at different depths and with different den-sities overlaps each other,the gravity anomalies produced by orebodies,particularly by the deep-scatedones, are usually masked.In order to solve the knotty problem,the proper orthogonal functions fitted to the Bougueranomaly can be selected in the ore district,so as to separate the local gravity anomalies due to the orehorizons from the measured anomalies.On that basis,we outlined successfully a tectono-metallogenicbelt,unveiled the structures in the ore district,delineated eleven local gravity anomalies,and chartedthe interested area in ore prospecting.The average densities of the rocks and the ores from table lshows that the minimum density of the ores is higher than the maximum one of the country rocks inthe ore district.Therefore, it may be considered that"wherever there are ores in a area,there isbound to be manifestation of gravity anomaly there",and the gravity data processing by means of themethod can be used in ore prospecting dircctly in such ore districts as Asheic.
Geochronology studies of the Early Paleozoic Honghai massive sulfide deposits and its geological significance in Kalatage area, eastern Tianshan Mountain.

MAO QiGui,FANG TongHui,WANG JingBin,WANG ShuLai,WANG Ning,

岩石学报 , 2010,
Abstract: The Honghai massive sulfide Cu-Zn deposit found in the Kalatage volcanic and volcanic-clastics belt in the eastern Tianshan Mountains. The drill cores studies indicate this volcanic and volcanic-clastics buildings are composed by two group of stratums: (1) overlain layers made up of intermediate and felsic volcanic rocks, volcanic breccias, tuff and interlayer tuff sandstone; (2) host-layers mainly composed of massive Cu-Zn sulfide Cu-Zn ore-body, basics, intermediate and felsic volcanic breccias, tuff breccias, tuff and sedimentary tuff. The sample for zircon U-Pb dating was collected at the button of overlain layers, and the sample for K-Ar dating was collected in the intensively altered mineralization zone. Zircon U-Pb dating get the crystallization age is 416.3±5.9Ma for the felsic volcanic rocks, which limit mineralization age. The K-Ar age is 424±7Ma for the sericitized rocks, which recorded the latest mineralization stage. The geochronology studies indicates the Honghai Cu-Zn deposit is an Early Paleozoic deposits, constrict the age of the lower volcanics in the Kalatage area,and also extend the prospecting potential space of the Kalatage and the eastern Tianshan Mountain areas.

SHEN Jian-zhong,ZHANG Xiao-min,

地球学报 , 1993,
Abstract: The driving heat source has been the unsolved problem encontered in the genetic models of sedimentary-exhalative base matal massive sulfide, the discovery and identification of high-heat-producing granite underlying Sedex deposit provide a new way to clarify this problem. HHP granite exists in the same geologic environment as Sedex deposit and has very high contents in radiogenic U, Th and K, which may drive the hydrothermal convective circulation system in its overlying sediments for the formation of Sedex deposit.

HAN Fa,Richard WHutchinson,

地球学报 , 1991,
Abstract: Broad and multi-faceted studies during the past 20 years have shown that all sedimentary exhalative deposits are formed on the seafloor by chemical precipitation from discharged metal-bearing hydrothermal fluids. The fluids are generated within the sub-area floor rock column by reaction between convectively circulated sea water and the rocks themselves. Differing rock columns in various tectonostratigraphic environments give rise to differing fluids and varieties of deposits. However, because of their common genetic process, all sedimentary exhalative deposits share a set of common identifying primary geologic characteristics, and it is of great significance for comparative investigating the origin of certain other deposits.The purpose of this paper is to briefly review the main geological and geochemical characteristics of the Dachang tin-polymetallic deposits, the genetic processes how they are formed, the deformation-metamorphism after ore-formation and its resulting geological characteristics. And then, it is to consider the relationship between the Dachang tin-polymetallic deposits and some strata-bound deposits including massive base metal sulfide deposits, greenstone belt gold lodes and stratiform tin deposits. The facts indicate that many of the geological and geochemical characteristics of the Dachang tin-polymetallic deposits are similar to those of the massive base metal sulfide deposits. These similarities suggest that many of the genetic and me-tamorphic processes involved in massive sulfide formation may have also contributed to formation of the Dachang deposits. So, Dachang deposits belong to the stratabound and stratiform tin deposits of tin-rich type of massive sulfide deposits.The specific tectono-stratigraphic environment formed Dachang tin-rich exhalative deposits is also discussed. The preliminary studies indicate that the following three conditions are necessary for the formation of these deposits (1) A convectively circulated hot brine system has been initiated by rifting; (2) Some involvement of older continental crust pre-enriched in tin in submarine exhalative system is obviously happened 5 (3) At least two or three successive tectono-magmatic stages are involved in the evolutionary metal-logenesis of the Dachang tin deposits.
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