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1.
The present paper investigates the stream sediment geochemistry, behavior of gold and associated elements, delineates Au-anomalous sites and defines related sources in the Wadi Umm Rilan area. Fifty three major and trace elements were analyzed using ICP-MS and treated applying various statistical and mapping techniques. The results showed a significant difference of mean and median Au and most chemical elements in the three portions of the area, and higher values were recorded in the western portion. Furthermore, Au-anomalous sites appeared in upper and lower parts of the Wadi Umm Rilan, along the tributaries of metavolcanic unit and near granitoid contacts. This indicates the main source of Au mineralization is related to emplacement of granitoid plutons and accompanying hydrothermal solutions. There are significant indications for the presence of more than one mineralization event forming a probable single major episode of mineralization in the area, involving Au, Pb and U mineralizations. Geology, geomorphologic aspects and weathering processes could control stream sediment geochemistry, anomalies of Au and associated elements, elemental association and their dispersion patterns. Therefore, the area is fruitful and regarded as a promising target for Au exploration, using Ag, As, Sb, Cd, Cs, and Tl as pathfinder elements.  相似文献   

2.
青海省巴硬格莉沟地区花岗岩的地质特征及其成矿意义   总被引：1，自引：1，他引：1  
青海省中部巴硬格莉沟地区的成矿作用受北西向的哇洪山—温泉构造岩浆岩带控制。区内广泛出露的印支燕山期花岗岩以及在断裂带附近矿化异常的地质特征表明 :印支—燕山期构造岩浆活动是巴硬格莉沟地区Cu、Pb、Zn、Ag等多金属矿成矿的主导因素 ,在哇洪山—温泉构造岩浆岩带 ,NS向、EW向的复合构造控制了本区内矿体和矿脉的展布。对区内花岗岩的地球化学特征研究表明 ,巴硬格莉沟地区中酸性岩类属于改造型的花岗岩类 ,花岗岩的K -Ar同位素年龄为印支期 ,且与矿石的Pb同位素年龄相近 ,说明巴硬格莉沟成矿时期与成岩年龄接近 ;并且推测成矿元素与花岗岩应来自同一源区。局部破碎变质带内花岗岩类中Cu、Pb、Zn成矿元素含量的相关性说明多金属成矿元素来自同一围岩 ,总体显示成矿不但严格受构造控制 ,而且成矿后期改造对它的叠加作用也十分显著。巴硬格莉沟地区加里东期以后的构造岩浆活动主要聚集了以碱质中酸性岩为主的花岗岩类 ,致使Cu、Pb、Zn、Ag为主的成矿元素分异并且重新富集。在北西向碱质酸性岩石系列附近遗留了规模大且同方向展布的断裂系列 ,在不同的构造部位多处出现成矿异常分别显示该区可能存在隐伏矿体。  相似文献   

3.
黑色岩系型矿床是矿床学研究的一个重要对象,其成因由于成矿作用复杂而存在争议。为深入理解这种复杂性并为解决争议提供参考信息,通过深入剖析国内外这类矿床的典型实例,述评了矿床成因研究的现状与进展,并进一步提出了值得加强研究的方向。全球黑色岩系矿床分布广泛,矿床形成过程中受多种地质作用影响,并可主要归纳为3种：海水、热水与生物有机成矿作用。其中,海水和热水为成矿提供元素及有利的成矿条件(如还原的沉积环境)。相比而言,生物有机质的成矿作用则主要体现在对海水和/或热水提供的元素进行富集,并在合适条件下成矿。可见,这3种成矿作用的多元复合作用使得成矿过程极其复杂,这是导致很多矿床成因至今未完全确定的一个重要原因。今后可从两方面开展深化研究：一是揭示多期复杂成矿演化过程;二是剖析生物有机成矿作用。这些认识对沉积岩型矿床的研究同样具有普遍参考意义。  相似文献   

4.
包志伟  李创举  祁进平 《岩石学报》2009,25(11):2951-2956
东秦岭栾川地区是著名的钼钨和铅锌多金属矿田.矿田内铅锌银矿床的成因及其与晚中生代构造岩浆活动关系一直存在诸多争论,其症结之一就是缺少可靠的同位素定年数据.铅锌银矿床赋存于中-晚元古代浅变质碳酸盐建造,野外地质观察发现碳酸盐-硫化物脉体及细粒黄铁矿呈细脉或浸染状沿辉长岩裂隙分布.辉长岩中锆石为无色透明柱状晶体,阴极发光图像显示清晰的震荡韵律环带,SHRIMP U-Pb年龄为147.5±1.7 Ma,MSWD=1.5.根据铅锌矿脉与辉长岩穿插关系,断定成矿作用晚于辉长岩结晶年龄,即不早于147.5±1.7 Ma.  相似文献   

5.
This study provides geochemical, mineralogical, and isotope data for rocks and ores from Lower Proterozoic black shale formations of the Kodar–Udokan structural and formational zone, which host the Khadatkanda gold—uranium deposit. The results indicate that the uranium and gold mineralizations were formed at different times in relation to different geodynamic settings. The gold mineralization is associated with the inception of the Syulban fault and has a juvenile source. The later Th–U mineralization originated during tectonic rejuvenation of the Syulban fault zone, while the sources of radioactive elements were presumably the underlying sediments of the Kodar Group, which are widespread throughout the area of the Baikal mountain region (BMR). Based on the above results, the Au–U mineralization in the study area can be recognized as unconformity-type deposits, analogous to the well-known deposits of Australia and Canada. In this connection, the Baikal mountain region has a good potential for the discovery of Au—U deposits.  相似文献   

6.
Geochemical exploration by stream sediment sampling using bulk leach extractable gold (BLEG) technique and applying concentration-number (C-N) fractal model, factor analysis (FA), and geochemical mineralization probability index (GMPI) resulted in the recognition of new Au occurrences around the Sukari gold mine in the central Eastern Desert of Egypt. The geochemical data of 128 stream sediment samples collected from the study area was used for delineating the geochemical anomalies and characterizing the dispersion trains of ore and associated elements (Au, Ag, As, Sb, Cu, Pb, Zn, Mo). Statistical analysis of the geochemical data applying the C-N fractal modeling enabled us to identify significant anomaly and background populations of the investigated elements and to construct reliable geochemical anomaly maps. Factor analysis using centered log-ratios (CLR), to address the problem of closed compositional data, revealed significant element associations for mineralization (Au, As, Mo, Zn, Ba), country rock compositions (Rb, Li, Be, Sn, Bi for granite, and Co, Cr, Ni for mafic rocks), and element mobility (e.g. Sb, Zr, and Ag). Weak and moderate Au anomalies that cannot be detected by factor score maps can be delineated clearly by using the C-N fractal method and GMPI distribution map. Our study revealed that Ag, As, and Sb are the main pathfinder elements for gold mineralization in arid to semiarid regions exemplified by the Sukari gold district. Silver can be used as a “direct” pathfinder, whereas As and Sb are “indirect” pathfinders for Au in such regions. The spatial distribution of Au and Ag anomalies indicate that gold mineralization in the Sukari district is structurally controlled. However, the spatial distribution of Cu, Pb, Zn, and Mo is controlled by mineralogical and lithological factors and is not related to any significant base metal deposits.  相似文献   

7.
Emerald deposits of Colombia are confined to lower Cretaceous shales of the Eastern Cordillera. The tectonic pattern of the deposits is related to deep reverse and large regional fault systems. Hydrofracturing is the main factor controlling emerald mineralization. It permitted to the hydrothermal solutions to permeate through fractures but also along stratification planes forming in this case stratabound mineralizations. Emerald occurs in calcite veins, veinlets, pockets and brecciated zones associated mainly with pyrite, quartz, parisite, codazzite and fluorite. Emerald mineralization belongs to an epigenetic hydrothermal process. The alternance of arenite-shale formations in the Cretaceous probably played an important role in the accumulation of solutions and in the propagation of the hydrothermal channels. The origin of emerald involves chemical elements mobilized by the fluids in the Cr-V-Fe-Al-Si-bearing black shales. The source of beryllium remains a problem and is discussed in the paper.  相似文献   

8.
湖南西北部黑色岩系中的贵金属矿化及找矿   总被引：2，自引：0，他引：2  
鲍振襄 《黄金地质》1995,1(3):28-33
湖南西北部下寒武统木昌组黑色岩系中蕴藏着丰富的镍钼钒多金属矿床及其伴生的贵金属矿化。可划分为两类岩性组合序列，分析赋存着镍钼－金银矿化和钒－银矿化。有机成矿作用对该类矿床（化）的形成起了主导作用，本区具有良好的成矿前景和找矿潜力。  相似文献   

9.
华北大陆边缘造山过程与成矿研究的重要进展和问题   总被引：62，自引：37，他引：25  
陈衍景  翟明国  蒋少涌 《岩石学报》2009,25(11):2695-2726
本文简要总结了国家973计划项目"华北大陆边缘造山过程与成矿"前4年取得的重要进展,包括提出了镁铁质岩石容矿的热液铜镍一贵金属矿床、浅成作用的概念,将热液成矿系统分为岩浆热液、变质热液和浅成热液三大系列;基于一批造山型银、铅锌、铜、钼等矿床的发现或识别,将造山金矿的概念和成矿分带模式拓展为造山型矿床;确定华北克拉通南缘和北缘均发生了印支期成矿事件,尤其是浆控高温热液型钼矿床;发现大陆内部浆控高温热液成矿系统以富CO_2、富钾、富氟为特征,不同于岛弧区同类矿床;挤压造山带的卡林型-类卡林型金矿成矿系统也以含CO_2-H_2O包裹体而区别于弧后盆岭省的同类成矿系统;发现中央造山带和中亚造山带在成矿类型、优势矿种等方面差异显著,缘于它们分别经历了弱增生-强碰撞和强增生-弱碰撞的造山作用;确定华北陆块及其陆缘造山带东部在燕山期大规模成矿,自西向东成矿年龄梯级变新,优势成矿类型和矿种不同,缘于太平洋板块作用叠合于造山带自身的演化;发现碰撞前的热液成矿系统均或多或少地遭受改造,甚至活化、再就位成另类矿床;在秦岭造山带新发现了1.9Ga和1.75Ga浆控热液钼矿床以及430Ma的造山型银金钼矿床,在兴蒙造山带新发现了泥盆纪造山型铜金矿床,据此预测了前中生代矿床的找矿潜力;提出矿床是地球动力学研究的探针,厘定秦岭-大别-苏鲁造山带在120Ma之后的隆升剥蚀幅度总体小于10km,平均每年0.04mm,快速隆升剥蚀只能发生在130Ma之前;初步厘定古亚洲洋沿索伦-延吉缝合带自西向东闭合于260～250Ma,古特提斯洋北支最终闭合于220Ma;揭示华北克拉通对于Kenor、Columbia、Rodinia、Gondwana和Pangea超大陆事件均有响应,发现了拉马甘迪(Lomagundi)事件的碳同位素正向漂移现象,确定孔兹岩系主要形成于2.3Ga以后.提出急需加强研究的重要科学问题是大陆碰撞造山事件的起止时限和标志,前中生代成矿系统的识别和预测,燕山期大规模成矿的区域规律性和差异性,构造域叠合-转化过程的细节和机理.  相似文献   

10.
The Wittichen Co–Ag–Bi–U mining area (Schwarzwald ore district, SW Germany) hosts several unconformity-related vein-type mineralizations within Variscan leucogranite and Permian to Triassic redbeds. The multistage mineralization formed at the intersection of two fault systems in the last 250 Ma. A Permo-Triassic ore stage I with minor U–Bi–quartz–fluorite mineralization is followed by a Jurassic to Cretaceous ore stage II with the main Ag and Co mineralization consisting of several generations of gangue minerals that host the sub-stages of U–Bi, Bi–Ag, Ni–As–Bi and Co–As–Bi. Important ore minerals are native elements, Co and Ni arsenides, and pitchblende; sulphides are absent. The Miocene ore stage III comprises barite with the Cu–Bi sulfosalts emplectite, wittichenite and aikinite, and the sulphides anilite and djurleite besides native Bi, chalcopyrite, sphalerite, galena and tennantite. The mineral-forming fluid system changed from low salinity (<5 wt.% NaCl) at high temperature (around 300°C) in Permian to highly saline (around 25 wt.% NaCl + CaCl2) at lower temperatures (50–150°C) in Triassic to Cretaceous times. Thermodynamic calculations and comparison with similar mineralizations worldwide show that the Mesozoic ore-forming fluid was alkaline with redox conditions above the hematite–magnetite buffer. We suggest that the precipitation mechanism for native elements, pitchblende and arsenides is a decrease in pH during fluid mixing processes. REE patterns in fluorite and the occurrence of Bi in all stages suggest a granitic source of some ore-forming elements, whereas, e.g. Ag, Co and Ni probably have been leached from the redbeds. The greater importance of Cu and isotope data indicates that the Miocene ore stage III is more influenced by fluids from the overlying redbeds and limestones than the earlier mineralization stages.  相似文献   

11.
The upper part of the Adediya Formation (Cambro-Ordivician) exposed in southwestern Sinai represents a very interesting succession. It contains mineralizations which are exceptionally rich in radioactive and rare earth elements as well as heavy metals. Field and several laboratory studies were carried out on this part of the Adediya Formation exposed in four stratigraphic sections distributed in a geographically wide area in southwestern Sinai.The radioactive mineralizations exist in sandstones, ironstone bodies and, to a much lesser extent, siltstones. Each of these rock types has a relatively wide range of textural characteristics. The recorded mineral assemblage consists of a large number of essential and accessory minerals some of which are radioactive and REE-bearing.The obtained field and laboratory data were implemented to determine the sedimentary history of the host rocks and the genesis of the mineral species which constitute the mineralizations. This included the identification of the types and effects of the various diagenetic processes and hydrothermal activity which led to the genesis of the recorded mineralizations. Also, the relative roles played by these post-depositional processes in determining the mineral, chemical and radioactive characteristics of the mineralizations and host rocks were assessed. These roles resulted in redistribution of the various elements especially the radioactive and rare earth elements as well as heavy metals during the epigenetic phase particularly by the action of supergene processes. A genetic model for the studied mineralizations is proposed.  相似文献   

12.
Increasing the prediction rate in the identification of mineralization zones using the stream sediment geochemical data is an essential issue in the regional exploration stage. The various univariate (such as fractal and probability plot (PP) methods) and multivariate methods (such as principal component analysis (PCA)) have been performed for interpreting the geochemical data and detecting the mineralization areas. In this study, a new geochemical criterion named geochemical anomaly intensity index (GAII) was proposed for geochemical anomaly mapping. This approach was developed based on the PCA method and the catchment basin coefficient (CBC). The GAII as a weighted geochemical index is calculated using the mineralization principal component (MPC) scores and CBC. GAII can be mapped and utilized for geochemical anomaly mapping and detecting the mineralization areas. Besides, GAII can identify paragenesis elements better than the current methods. In this research, GAII was successfully used to generate geochemical anomaly maps on shear zone gold mineralization in the southwest of Saqqez, NW Iran. The geochemical data have been divided into three groups based on catchment basins and the host rock type. Then the MPCs and paragenesis elements of Au mineralization have been obtained individually using PCA. Three mineralization paragenesis groups consisting of (Au, Sn), (Au, W), and (Au, As, Sb and Ba) have been recognized for different catchment basins of the southwest of Saqqez district using PCA. GAII was calculated and mapped based on the CBC(Au, Sn), CBC(Au, W), CBC(Au, As, Sb, Ba), and their MPC scores. GAII accurately detected the Au mineralization zones and improved the geochemical anomaly map in this area compared to the PP method, concentration-area fractal model, and U-spatial statistics method. The results demonstrated that GAII was successfully used for (a) identifying the mineralization paragenesis elements, (b) intensifying the geochemical anomaly, and (c) increasing the prediction rate of mineralization zones. The shear zone gold mineralization areas in the southwest of Saqqez district were effectively detected using this new data analysis approach. GAII has provided better results than the current PP method, concentration-area fractal model, and U-spatial statistics method.  相似文献   

13.
Changes in biomass, growth form and shoot net primary production in an eelgrass, Zostera marina L., bed were monitored along transects at three tidal heights in Netarts Bay, Oregon, from May 1979 through June 1981. During the growing season, April through October, the mean plastochrone interval was 16.5 d along the low intertidal transect and 11.6 d along the high intertidal transect. The mean export interval was 13.3 d along the low intertidal transect and 11.6 d along the high intertidal transect. The life span of a leaf averaged 48 d along the low intertidal transect and 36 d along the high intertidal transect. Shoot density was positively correlated with mean leaf area index (LAI) until the LAI reached 3.8 to 5.5, above which LAI was negatively correlated with density. The maximum Zostera biomass ranged from 143 (high intertidal transect) to 463 (low intertidal transect) g dry wt m?2. Maximum values of shoot net production ranged from 4.7 (high intertidal transect) to 13.6 (low intertidal transect) g dry wt m?2d?1. Zostera shoot net production was related to light and to the physical damage to the shoots associated with a rapid accumulation of Enteromorpha biomass in the bay. In addition, patterns of biomass accumulation were related to the duration of water coverage, as determined by both tidal height and local impoundments of water. At all transects, biomass sloughed was equal to at least 50% of the shoot net primary production in that area during that time period; sloughed leaves accounted for 25 to 97% of these losses. An estimate of the total annual net primary production of aboveground Zostera in the bed was 17,500 kg, dry wt (SE=3,080 kg dry wt), which was equivalent to a mean annual rate of 383 g C m?2 (SE=67 g C m?2)  相似文献   

14.

The new geochemical data obtained of cupriferous sandstones of the Orenburg area of the Ural region show that the Permian host stratum could have served as the source of rare-earth elements and other microelements for the ore-forming fluids. They confirm the possibility of using a convection model to explain the genesis of the copper ores studied. This model indicates the likely multistage development of mineralization to significant depths, like in the Manto deposits in Chili. Consequently, the Permian cupriferous sandstones of the southwestern area of the Ural region can be considered a very promising source of raw material for the development of copper industry in the area.

  相似文献   

15.
本文将康滇地轴中南段元古宙主要铀矿化类型划分为四个主要类型七个亚类。初步总结了元古宙铀成矿的基本特征 ,提出铀矿化 (96 0 - 6 0 0 Ma)是晋宁 -澄江运动的产物 ,与该区同层位中铜矿化改造富集时期一致 ;并讨论了康滇地轴中南段不整合面型铀矿床成矿条件评价问题 ,提出中、上元古界不整合面附近成矿远景  相似文献   

16.
《China Geology》2021,4(2):245-255
The Central Africa Fold Belt (CAFB) is a collision belt endowed with gold deposits in Eastern Cameroon area mined for about 50 years. However, favorable areas for gold exploration are poorly known. This paper presents (1) the kinematics of the brittle deformation in the Kékem area in the SW portion of the Central Cameroon Shear Zone and (2) constraints gold mineralization events with respect to the collisional evolution of the CAFB. The authors interpret that the conjugate ENE to E and NNW to NW trending lineament corresponds to the synthetic (R) and the antithetic (R’) shears, which accompanied the dextral slip along the NE to ENE striking shear. The latter coincides with the last 570–552 Ma D3 dextral simple shear-dominated transpression, which is parallel to the Bétaré Oya shear zone hosting gold deposits. Gold mineralizations, which mainly occurred during the last dextral shearing, are disseminated within quartz veins associated to Riedel’s previous structures reactivated due to late collisional activities of the CAFB as brittle deformation. Gold mineralizations occurred mainly during the 570–552 Ma D3 event. The reactivation, which might be due to dextral simple shear during mylonitzation, plausibly remobilized the early gold deposits hosted in syn-compressional rocks and/or possibly focused deep-sourced fluid mixed with those released by dehydration. Therefore, the Central Cameroon Shear Zone where Kékem is located, and which shows similar petrographical and structural features to those controling Batouri gold district, is a target area for gold exploration in Cameroon.  相似文献   

17.
华北地块北缘中段分布着许多大中型铅锌银矿床,依据其成因特征可划分为四种类型:沉积喷气型矿床、叠加改造型矿床、与大红峪期碱性火山活动有关的浅成低温热液矿床、与中生代火山-斑岩活动有关的热液矿床。成矿作用具多期多成因的特点:古元古代火山沉积作用不仅可能形成了区内最早的VMS型矿床,而且成为区内最重要的矿源层;中元古代早期形成了本区最古老的浅成热液银多金属矿床;中元古代中期形成了又一期VMS型矿床;而中生代是本区铅锌银最重要的成矿期,成矿显然受基底的制约。  相似文献   

18.
Uranium and thorium isotopic composition of kasolite [Pb(UO2)SiO4-(H2O)] from Jabal Sayid area was determined by thermal ionization mass spectrometry. Secondary electron imaging, back-scattered electron imaging, and energy dispersive spectral scans were used to investigate the mineralogical characteristics of this uranyl mineral phase. Distinct crystal faces and crystal growth of kasolite from the study area confirm mineral precipitation near the surface from the circulating groundwater. The obtained data were used to interpret the mechanism of uranium mobility in Jabal Sayid weathering profile and to construct a tentative model to explain the isotopic evolution of uranium and thorium. This model indicates that (1) uranium was leached at depth, (2) uranyl mineralization was precipitated along fractures and cavities in the host rocks during humid conditions and pluvial periods, (3) preferential leaching of 234U from uranyl mineralization by recoil processes was continuous indicative of a weakly circulating groundwater, and (4) 234U-deficiency resulted in isotopic signatures characterized by low 234U/238U and high 230Th/234U ratios. The modification pattern of these activity ratios suggests that uranyl mineralization of Jabal Sayid, most probably, has been precipitated during the same Late Quaternary pluvial periods responsible for the formation of the corresponding mineralizations in the Eastern Desert of Egypt.  相似文献   

19.
Eastern Iran has great potential for the discovery of different types of mineralization. The study area encompasses Tertiary magmatism in the northern Lut block located in northern Khur, South Khorasan, eastern Iran and is mostly covered by volcanic rocks, which are intruded by porphyritic subvolcanic intrusions in some places. Application of the spectral angle mapper (SAM) technique to Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images detected sericitic, argillic, and propylitic alterations, silicification, and secondary iron oxides. The alteration is linear and associated within vein-type mineralization. Twelve prospective areas are selected for detailed exploration and based on our processing results, in addition to NW-SE faults, which are associated with Cu mineralization indications, NE-SW faults are also shown to be important. Based on the presence of subvolcanic rocks and numerous Cu ± Pb-Zn vein-type mineralizations, extensive alteration, high anomaly of Cu and Zn (up to 100 ppm), the age (43.6 to 31.4 Ma) and the initial 87Sr/86Sr ratio (0.7047 to 0.7065) of the igneous rocks, and the metallogenic epoch of the Lut block (middle Eocene-lower Oligocene) for the formation of porphyry Cu and epithermal deposits, the studied area shows great potential for porphyry copper deposits.  相似文献   

20.
The El Kef area, Tunisia, is host of the official stratotype of the K/P boundary and of a complex metallic and non-metallic mineralization at Djebel Sekarna, encompassing syn(dia)genetic shale- and carbonate-hosted Zn–P and epigenetic Pb–Zn–Ba ore mineralizations. Micropaleontological, geological, mineralogical, and chemical studies (major and minor elements, C- and O-isotopes) of Upper Santonian to Lower Eocene calcareous-siliciclastic sediments resulted in a subdivision of this mineralization into eight mineralizing stages. Stages 1 and 2 (late Cretaceous–early Paleogene) are representative of syn(diagenetic) shale- and carbonate-hosted sulfidic and siliceous (Fe)–Zn–P mineralization deposited in shallow marine to slightly brackish sediments. Stages 3–5 (early Eocene respectively—pre- and post-Nummulites involutus-exilis zones) are representatives of epigenetic sulfidic and sulfatic (Fe)–Zn–Pb–Ba mineralizations at temperatures as high as 170/200°C and stages 6 and 7 (early Eocene respectively—post-Alveolina oblonga zone) cover the non-sulfidic Zn–(Pb) mineralization at temperatures as high as 60°C which is transitional from hypogene into supergene mineralization (“epithermal calamine deposits”). Stage 8 represents alteration of the pre-existing mineral assemblages in course of the Holocene weathering. The Cretaceous through Paleogene aquatic system is characterized by a poisoning of the sea with base metals, mainly Zn, and the atmosphere was chocked with clouds of fine-grained volcanic ejecta. Both processes contributed to the build-up of Zn–(Pb) deposits and vast, but uneconomic bentonitic clay deposits around the K/P boundary. Ore mineralization in the El Kef area is a multiple-phase process which reached its climax during the early Eocene as indicated by the large foram zones. These inorganic concentration processes resulting in the formation of mineral deposits had obviously also a negative effect on the long-term course of regional Earth’s biological history during the late Cretaceous–early Eocene period with lethal consequences for some species. The joint studies of inorganic and organic data reveal that such extraordinary metallogenetic processes close to the K/P boundary in its stratotype area in Tunisia were “strictly terrestrial”.  相似文献   

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