Central European Journal of Geosciences最新文献

{"title":"Mathiasite-loveringite and priderite in mantle xenoliths from the Alto Paranaíba Igneous Province, Brazil: genesis and constraints on mantle metasomatism","authors":"V. Almeida, V. Janasi, D. P. Svisero, F. Nannini","doi":"10.2478/s13533-012-0197-5","DOIUrl":"https://doi.org/10.2478/s13533-012-0197-5","url":null,"abstract":"Alkali-bearing Ti oxides were identified in mantle xenoliths enclosed in kimberlite-like rocks from Limeira 1 alkaline intrusion from the Alto Paranaíba Igneous Province, southeastern Brazil. The metasomatic mineral assemblages include mathiasite-loveringite and priderite associated with clinopyroxene, phlogopite, ilmenite and rutile. Mathiasite-loveringite (55–60 wt.% TiO2; 5.2–6.7 wt.% ZrO2) occurs in peridotite xenoliths rimming chromite (∼50 wt.% Cr2O3) and subordinate ilmenite (12–13.4 wt.% MgO) in double reaction rim coronas. Priderite (Ba/(K+Ba)< 0.05) occurs in phlogopite-rich xenoliths as lamellae within Mg-ilmenite (8.4–9.8 wt.% MgO) or as intergrowths in rutile crystals that may be included in sagenitic phlogopite. Mathiasite-loveringite was formed by reaction of peridotite primary minerals with alkaline melts. The priderite was formed by reaction of peridotite minerals with ultrapotassic melts. Disequilibrium textures and chemical zoning of associated minerals suggest that the metasomatic reactions responsible for the formation of the alkali-bearing Ti oxides took place shortly prior the entrainment of the xenoliths in the host magma, and is not connected to old (Proterozoic) mantle enrichment events.","PeriodicalId":49092,"journal":{"name":"Central European Journal of Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80155476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extreme chemical conditions of crystallisation of Umbrian Melilitolites and wealth of rare, late stage/hydrothermal minerals","authors":"F. Stoppa, M. Schiazza","doi":"10.2478/s13533-012-0190-z","DOIUrl":"https://doi.org/10.2478/s13533-012-0190-z","url":null,"abstract":"Melilitolites of the Umbria Latium Ultra-alkaline District display a complete crystallisation sequence of peculiar, late-stage mineral phases and hydrothermal/cement minerals, analogous to fractionated mineral associations from the Kola Peninsula. This paper summarises 20 years of research which has resulted in the identification of a large number of mineral species, some very rare or completely new and some not yet classified. The progressive increasing alkalinity of the residual liquid allowed the formation of Zr-Ti phases and further delhayelitemacdonaldite mineral crystallisation in the groundmass. The presence of leucite and kalsilite in the igneous assemblage is unusual and gives a kamafugitic nature to the rocks. Passage to non-igneous temperatures (T<600 °C) is marked by the metastable reaction and formation of a rare and complex zeolite association (T<300 °C). Circulation of low-temperature (T<100 °C) K-Ca-Ba-CO2-SO2-fluids led to the precipitation of sulphates and hydrated and/or hydroxylated silicate-sulphate-carbonates. As a whole, this mineral assemblage can be considered typical of ultra-alkaline carbonatitic rocks.","PeriodicalId":49092,"journal":{"name":"Central European Journal of Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82455373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"X-ray crystallography and mineral chemistry of bastnaesite from Kanigiri granite, Prakasam district, Andhra Pradesh, India","authors":"Y. Singh, G. Nagendra Babu, R. Viswanathan, M. Sai Baba, A. Rai, P. S. Parihar","doi":"10.2478/s13533-012-0187-7","DOIUrl":"https://doi.org/10.2478/s13533-012-0187-7","url":null,"abstract":"The authors report the results of X-ray diffraction (XRD) and geochemical studies on bastnaesites (lanthanum cerium fluoro-carbonate) hosted in alkali Kanigiri Granite of the Prakasam district in Andhra Pradesh, India. The XRD pattern of the investigated bastnaesite displays sharply-defined reflections. The observed d-spacings of the bastnaesite are in very close agreement with those published for bastnaesite standard in International Centre for Diffraction Data (ICDD) Card No. 11–340. The calculated unit cell parameters (ao; co) and unit cell volume (V) of the studied bastnaesite (ao 7.1301–7.1413 Å, co 9.7643–9.7902Å and V 429.8940–432.3875 Å3) are almost equal to values published for bastnaesite standard (co 7.1290 Å, co 9.7744 Å and V 430.19 Å3) in the relevant data card.Geochemical data of bastnaesite reveals high content of Ce (mean 27.22%) followed by La (mean 16.82%), Nd (mean 6.12%) and Pr (mean 1.91%). Compared to light REE (LREE) content (mean 437165 ppm), heavy REE (HREE) content (mean 5867 ppm) is drastically low, with unusually high LREE/HREE ratio (mean 80). The chondrite-normalised plot also exhibits drastic enrichment of LREE relative to HREE with pronounced negative Euanomaly (mean Eu/Eu* = 0.15). High (LREE)N / (HREE)N, (La/Lu)N, (La/Yb)N and (Ce/Yb)N ratios reveal higher fractionation of LREE relative to HREE. The rare earth element (REE) contents of the studied bastnaesite are very close to REE contents of bastnaesite hosted in alkali syenite from Madagascar. The presence of bastnaesite in Kanigiri Granite and soils derived from it enhances the scope of further exploration for bastnaesite in several bodies of alkaline rocks and alkali granitoids present along the eastern margins of the Cuddapah basin, Andhra Pradesh.","PeriodicalId":49092,"journal":{"name":"Central European Journal of Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88613291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The volcanic-subvolcanic rocks of the fernando de noronha archipelago, southern atlantic ocean: Mineral chemistry","authors":"Rosana Peporine Lopes, M. Ulbrich, H. Ulbrich","doi":"10.2478/s13533-012-0195-7","DOIUrl":"https://doi.org/10.2478/s13533-012-0195-7","url":null,"abstract":"Fernando de Noronha archipelago presents an older Remédios Formation with subvolcanic intrusions, belonging to two different alkaline series, the sodic (undersaturated: basanites, tephrites, essexites, tephriphonolites, phonolites), and potassic ones (mildly undersaturated to silicic, with alkali basalts, basaltic trachyandesites, trachyandesites, trachytes), and lamprophyres. The upper Quixaba Formation presents nephelinite flows and basanites. A third minor unit, São José, is constituted by basanites carrying mantle xenoliths. Magnesian olivines occur in the Remédios basanites and alkali basalts, and in nephelinites. Melilites are present as groundmass grains in melilite melanephelinites (MEM). Clinopyroxenes (cpx) are mostly salites to titaniferous salites (Remédios sodic series), grading into aegirines in the differentiated aphyric phonolites. Cpx in the lamprophyres show disequilibrium textures. In the Quixaba flows, cpx are salites, enriched in Mg (especially in MEM). Amphiboles, remarkably, are common in tephriphonolites and phonolites and in basaltic trachyandesites, sometimes with disequilibrum zoning textures, and a conspicuous phase in lamprophyres. Dark micas are present as groundmass plates in MEM, OLM and PYM (olivine and pyroxene melanephelinites), with compositional variety (enriched in Ti, Ba, Sr) depending on the composition of the parent rock; BaO can be as high as 16–19%. Feldspars crystallize as calcic plagioclases, sanidines and anorthoclases, depending on the rock types, as phenocrysts and in groundmass, both in Quixaba and Remédios rocks; they are absent in nephelinites. Nephelines are found in Remédios sodic series types and Quixaba rocks. Haüyne and noseane are rarely observed in Remédios rocks.","PeriodicalId":49092,"journal":{"name":"Central European Journal of Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72568268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrology of potassic alkaline ultramafic and carbonatitic rocks from Planalto da Serra (Mato Grosso State), Brazil","authors":"P. Comin-Chiaramonti, C. B. Gomes, Â. Min, E. Ruberti, V. Girardi, F. Slejko, R. Neder, F. E. Pinho","doi":"10.2478/s13533-012-0196-6","DOIUrl":"https://doi.org/10.2478/s13533-012-0196-6","url":null,"abstract":"The Planalto da Serra igneous rocks form plugs, necks and dykes of carbonate-rich ultramafic lamprophyres (aillikites and glimmerites with kamafugitic affinity) and carbonatites (alvikites and beforsites). Phlogopite and/or tetraphlogopite, diopside and melanitic garnet are restricted to aillikitic rock-types, whereas pyroclore occurs only in carbonatites. Aillikites and carbonatites are altered to hydrotermalites, having chlorite and serpentine as dominant minerals. Planalto da Serra igneous rock association has kamafugitic affinity (i.e. effusive, ultrapotassic. High LREE/HREE fractionation, incompatible elements data and Sr-Nd isotopes, suggest that the K-ultramafic alkaline and carbonatite rocks originated from a variably metasomatized mantle source enriched in radiogenic Sr. Crustal contamination is negligible or absent. Age values of 600 Ma rule out the geochronological relationship between the investigated intrusions and the Mesozoic alkaline bodies from the Azimuth 125° lineament. The TDM model ages allow to conclude that Planalto da Serra magma is derived from the partial melting of a mantle source metasomatised by K-rich carbonatated melt during the Early to Late Neoproterozoic. On the basis of alkaline magmatism repetitions at 600 Ma and 90–80 Ma we question the subsistence of a stationary mantle plume for so long time.","PeriodicalId":49092,"journal":{"name":"Central European Journal of Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78459871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"REE mineralization in the carbonatites of the sung valley ultramafic-alkaline-carbonatite complex, Meghalaya, India","authors":"M. Sadiq, A. Ranjith, R. K. Umrao","doi":"10.2478/s13533-012-0191-y","DOIUrl":"https://doi.org/10.2478/s13533-012-0191-y","url":null,"abstract":"The Early Cretaceous Sung Valley Ultramafic-Alkaline-Carbonatite (SUAC) complex intruded the Proterozoic Shillong Group of rocks and located in the East Khasi Hills and West Jaintia Hills districts of Meghalaya. The SUAC complex is a bowl-shaped depression covering an area of about 26 km2 and is comprised serpentinised peridotite forming the core of the complex with pyroxenite rim. Alkaline rocks are dominantly ijolite and nepheline syenite, occur as ring-shaped bodies as well as dykes. Carbonatites are, the youngest intrusive phase in the complex, where they form oval-shaped bodies, small dykes and veins. During the course of large scale mapping in parts of the Sung Valley complex, eleven carbonatite bodies were delineated. These isolated carbonatite bodies have a general NW-SE and E-W trend and vary from 20–125 m long and 10–40 m wide. Calcite carbonatite is the dominant variety and comprises minor dolomite and apatite and accessory olivine, magnetite, pyrochlore and phlogopite. The REE-bearing minerals identified in the Sung Valley carbonatites are bastnäsite-(Ce), ancylite-(Ce), belovite-(Ce), britholite-(Ce) and pyrochlore that are associated with calcite and apatite. The presence of REE carbonates and phosphates associated with REE-Nb bearing pyrochlore enhances the economic potential of the Sung Valley carbonatites. Trace-element geochemistry also reveals an enrichment of LREEs in the carbonatites and average ΣREE value of 0.102% in 26 bed rock samples. Channel samples shows average ΣREE values of 0.103 wt%. Moreover, few samples from carbonatite bodies has indicated relatively higher values for Sn, Hf, Ta and U. Since the present study focuses surface evaluation of REE, therefore, detailed subsurface exploration will be of immense help to determine the REE and other associated mineralization of the Sung Valley carbonatite prospect.","PeriodicalId":49092,"journal":{"name":"Central European Journal of Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79496135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Occurrence of phlogopite in the Finero Mafic layered complex","authors":"T. Giovanardi, M. Mazzucchelli, A. Zanetti, A. Langone, M. Tiepolo, A. Cipriani","doi":"10.2478/s13533-012-0186-8","DOIUrl":"https://doi.org/10.2478/s13533-012-0186-8","url":null,"abstract":"Phlogopite-bearing lithologies are the main constituent of the Phlogopite-Peridotite unit of the Finero sequence and the result of pervasive migration of metasomatizing melts/fluids. Conversely, the presence of phlogopite within the associated Finero Mafic Complex, a mafic-ultramafic pluton intruded into the metamorphic basement of the Adria plate, is mentioned in literature as rare. Recent detailed fieldwork has evidenced the presence of two distinct phlogopite-rich ultramafic lithologies within the Amphibole-Peridotite unit of the Finero Mafic Complex, where phlogopite is always associated with amphibole. Field and petrographic features of these occurrences, as well as major- and trace-element mineral chemistry, are here presented to i) place constraints on the nature of the parent melt from which they have been generated and ii) to address their relationship with the other lithologies of the Finero Complex. We find that these rocks were formed by late melt migrations along shear zones under high-T conditions. The geochemical affinity of these lithologies is different to the tholeiitic-transitional affinity reported in literature for the Finero Mafic Complex. The enrichment in LREE, Th, U and Sr of the associated amphibole possibly suggests that these phlogopite-bearing lithologies are genetically related to the metasomatic events that have affected the Finero mantle massif.","PeriodicalId":49092,"journal":{"name":"Central European Journal of Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2478/s13533-012-0186-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72368843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fluid-rock interaction in the Kangankunde Carbonatite Complex, Malawi: SEM based evidence for late stage pervasive hydrothermal mineralisation","authors":"R. Duraiswami, Tahira N. Shaikh","doi":"10.2478/s13533-012-0192-x","DOIUrl":"https://doi.org/10.2478/s13533-012-0192-x","url":null,"abstract":"The Kangankunde Carbonatite Complex from the Cretaceous Chilwa Alkaline Province in southern Malawi contains ankeritic and siderite carbonatite that are affected by late stage remobilisation by a carbothermal or hydrothermal fluid. The coarse pegmatitic siderite carbonatite that hosts exotic minerals like monazite, synchysite, bastnasite, strontianite and apatite in vugs and cavities constitutes some of the richest rare earth deposits in the world. Besides these minerals, our studies reveal the presence of collinsite and aragonite from the siderite carbonatite. Fine drusy monazites are seen as overgrowths on thin veinlets of siderite within the rare earth mineralised zones. We present unambiguous SEM-based surface textural evidence such as presence of dissolution-corrosion features like etching along cleavage, solution channels, solution pits, sinstered scaly surface, etc. along with rare earth mineralisation that suggests the exotic minerals in the siderite carbonatite did not crystallise from carbonate magma and are a result of sub-solidus processes involving carbonatite-derived fluids. We believe that the monazite-synchysitebastnasite-strontianite-collinsite assemblages were formed by juvenile post magmatic hydrothermal alteration of pre-existing carbonatite by a complex CO2-rich and alkali chloride-carbonate-bearing fluid at ∼250 to 400°C in an open system. This late ‘magmatic’ to ‘hydrothermal’ activity was responsible for considerable changes in rock texture and mineralogy leading to mobility of rare earth elements during fluid-rock interaction. These aspects need to be properly understood and addressed before using trace and rare earth element (REE) geochemistry in interpreting carbonatite genesis.","PeriodicalId":49092,"journal":{"name":"Central European Journal of Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76884269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Preface — A special issue (Part-I): Mafic-ultramafic rocks and alkaline-carbonatitic magmatism and associated hydrothermal mineralization — Dedication to Piero Comin-Chiaramonti","authors":"L. G. Gwalani, C. B. Gomes","doi":"10.2478/s13533-012-0194-8","DOIUrl":"https://doi.org/10.2478/s13533-012-0194-8","url":null,"abstract":"Awarded with the degrees of a B.Sc. in Human Sciences (1961) and a Ph.D. in Petrology (1967) by the University of Trieste in Italy, Piero Comin-Chiaramonti (Figure 1) eventually spent most of his academic career in this institution, holding the positions of Assistant Professor (1967-1983) and Associated Professor (1983-1986). He was inducted as a full Professor in the Faculty of Sciences of the University of Palermo in 1986, where he remained until assigned to the Faculty of Engineering of the University of Trieste in 1993. There he initially worked as a Professor of Petrology (Faculty of Sciences) and later as a Professor of Environmental Geology and Environmental Geochemistry (Faculty of Enginnering). It was through the efforts and innovations of Professor Comin-Chiaramonti, both in the teaching process and in the development of research facilities, that the Engineering Department of the University of Trieste has ∗E-mail: lgwalani@gmail.com, http://lggwalani.jimdo.com/ †E-mail: cgomes@usp.br today attained world-wide recognition. In 2009, he was granted the award of \"Eminent Scientist\" by the Faculty of Engineering, and retired from active service in the following year. He is now devoting part of his time to research activites. With his remarkable skill, greater efficiency, resolute determination and untiring efforts, Professor CominChiaramonti nursed and actively participated as a member and critical reviewer of several international scientific journals and as a consultant reviewer of some organizations such as COFIN (Co-Financial support from the Italian Ministry for University and Scientific Research), CNR (National Research Council, Italy), MIUR (Ministry of University and Research) and the Georgian National Science Foundation. We take this opportunity to assure him that we shall keep his example always before us \"duty before self\" and shall do everything possible to keep up the progress he has initiated. Professor Comin-Chiaramonti has always been a strong proponent of international collaboration in research and the transfer of knowledge and skills in geosciences. He","PeriodicalId":49092,"journal":{"name":"Central European Journal of Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81366573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tsumoite (BiTe) and associated Ni-PGE mineralization from Gondpipri mafic-ultramafic complex, Bastar Craton, Central India: mineralogy and genetic significance","authors":"M. Dora, H. Singh, A. Kundu, M. Shareef, K. Randive, S. Joshi","doi":"10.2478/s13533-012-0185-9","DOIUrl":"https://doi.org/10.2478/s13533-012-0185-9","url":null,"abstract":"This paper reports the occurrence of Tsumoite (a bismuth telluride) in the Heti Cu-Ni-PGM prospect, Gondpipri mafic-ultramafic complex, Central India. The Gondpipri complex consists of several tectonically dismembered gabbronorite-gabbro-anorthositic gabbro — olivine gabbro -websterite disposed in ∼10 km long tonalite-trondhjemitegranodiorite (TTG) and charnockite-enderbite suite of rocks. The mineralization occurs in the sulphide zone hosted by gabbro variants. The host rocks have been deformed and metamorphosed to granulite grade and subjected to various degrees of hydrothermal alteration. The mineralization comprises chalcopyrite, pentlandite, pyrrhotite, cubanite, millerite, and pyrite. In addition to these, occur (1) tsumoite (2) PGM in the form of moncheite, merenskyite, Pd-mellonite, and Pt-Pd-Te-Bi-Fe-S alloy.The present study indicates that the mineralization occurs in two stages related to: (i) magmatic and (ii) hydrothermal remobilization and transport of Cu-rich sulphides, tsumoite and PGM, and their re-deposition in hydrosilicate alteration zones. It is possible that the mineralization at Heti formed at different stages of bismuth activity under variable fS2, T, and fTe2 conditions due to change in total concentration of Te and S and /or cooling. Since the role of S is limited, Te and cooling are important factor influencing mineralogy and composition of tsumoite and associated mineralization. Mineralization occurs in two different modes of occurrences. The early mineralisation occur as blebs, specks and dissemination of sulphides, viz. pyrrhotite, chalcopyrite, pentlandite and minor pyrite ± PGM, whereas later mineralisation occur as stringers, minor veins of sulphides viz. pyrite, millerite, cubanite, sijenite, tsumoite and ± PGM.Mineral assemblages and textural relationships at Heti has indicated precipitation of tsumoite and associated PGM along fractures and secondary silicates, which confirms their hydrothermal origin.","PeriodicalId":49092,"journal":{"name":"Central European Journal of Geosciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72642367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}