Mineralium Deposita最新文献

{"title":"Global constraints on exhumation rates during porphyry copper formation and supergene enrichment: applications to exploration as illustrated from the Central Andes","authors":"Laura Evenstar, Simon Dahlström, Adrian Hartley, T. Campbell McCuaig, Anne Mather, Joe Shaw","doi":"10.1007/s00126-024-01303-1","DOIUrl":"https://doi.org/10.1007/s00126-024-01303-1","url":null,"abstract":"<p>Currently, 60% of the world’s copper production comes from porphyry copper deposits, often significantly enriched by surface weathering. This paper uses new global datasets and previous work to review the critical processes required for porphyry copper formation and supergene enrichment. Porphyry copper formation requires a subducting arc to create a source magma which traverses a thickened crust subject to high exhumation rates during formation, ranging from 100’s to 1,000’s m/m.y. High exhumation rates potentially trigger magma decompression, causing fluid release, opening fluid pathways along faults and lineaments and/or facilitating telescoping, whereby early porphyry-style mineralization is overprinted and enriched by high-sulfidation mineralization at shallower crustal levels. Later supergene enrichment of the deposit requires precipitation rates &gt; 120 mm/yr and exhumation rates ranging from 10’s to 100’s m/m.y. This allows copper sulfide sources to be continually refreshed for weathering but restricts the amount of erosion. Using the Central Andes, one of the world’s most critical porphyry copper provinces, the understanding gained from analyzing these global databases can explain the temporal and spatial pattern of known deposits. These constraints were used to inform mappable target criteria and data required for mineral exploration at a range of different scales, from orogen (&gt; 100,000 km²), to terrane (100,000–1,000 km²) to arc (1,000–100 km²). The results can be used to help illustrate and inform global exploration strategies for supergene-enriched porphyry copper deposits.</p>","PeriodicalId":18682,"journal":{"name":"Mineralium Deposita","volume":"75 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141880250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revising PGE deposition and remobilization mechanisms using new data from the historic Vermilion and Crean Hill mines, Sudbury, Canada","authors":"Carol-Anne Généreux, Bruno Lafrance","doi":"10.1007/s00126-024-01301-3","DOIUrl":"https://doi.org/10.1007/s00126-024-01301-3","url":null,"abstract":"<p>Platinum-group element (PGE) mineralization associated with the Sudbury Igneous Complex (SIC), Canada, generally occurs within brecciated footwall rocks. At the Crean Hill and Vermilion deposits, variations in the ore mineralogy, textures, and whole rock geochemical signatures suggest that PGE deposition involved three stages. During the magmatic stage, sulfide melts were segregated at the base of the SIC and infiltrated the footwall rocks to form sulfide(-PGE) breccia and disseminated PGE mineralization (Crean Hill), and sulfide-PGE veins (Vermilion). Sulfide fractionation is suggested by the disappearance of Ru-bearing michenerite, a decrease in Ru, Rh and Ir tenors, and an increase in Pt, Pd and Au tenors and Cu/Ni away from the SIC contact. The syn-tectonic remobilization stage occurred between ~ 480–550 °C, as suggested by the composition of shear-hosted gersdorffite. At Crean Hill, Pd and Au were decoupled from Pt and remobilized via fluids into the footwall rocks, resulting in Pd and Au enrichment as disseminated michenerite and argentian gold along shear zones. At Vermilion, higher fluid-rock ratios and metamorphic semi-metal melts caused extensive remobilization of Pt, Pd and Au, and deposition of complex telluride, antimonide and arsenide grains within shear zones. A late metasomatic stage at &lt; 300 °C (gersdorffite composition) is observed at Vermilion only, where it caused epidote-albite-quartz-calcite alteration of the SIC rocks and deposition of low-temperature sulfides and precious metals in veins crosscutting shear zones. Together, these findings demonstrate how PGE mineralization should be examined relative to its host rock geology and evolution to resolve the distribution of precious metals in modified Ni-Cu-PGE deposits.</p>","PeriodicalId":18682,"journal":{"name":"Mineralium Deposita","volume":"25 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141836783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unraveling the evolution of the Bodó W-skarn district in the Seridó Mineral Province (NE-Brazil): constraints from C-O stable isotopes, thermodynamic modeling, and geochronology","authors":"Dinarte Lucas, Maria Helena B. M. Hollanda, João Adauto de Souza Neto, Renato Moraes, Laécio Cunha de Souza","doi":"10.1007/s00126-024-01300-4","DOIUrl":"https://doi.org/10.1007/s00126-024-01300-4","url":null,"abstract":"<p>Tungsten mineralization in the Bodó mineral district (9 Mt with an average grade of 2% WO₃) is in a sequence of metasomatized marbles and W-(Mo)-skarn lenses in the Seridó Belt, northern Borborema Province. The marble lenses have variable amounts of diopside, grossular, scapolite, phlogopite, and tremolite. The skarn lenses are mainly composed of massive grossular, diopside, vesuvianite, epidote, and quartz. A spatially related granite yielded a SHRIMP U‒Pb zircon date of 536.6 ± 3.4 Ma and a ⁴⁰Ar/³⁹Ar biotite date of 490.65 ± 0.67 Ma, whereas a nearby pegmatite yielded a ⁴⁰Ar/³⁹Ar muscovite date of 501.63 ± 0.59 Ma. Literature data for molybdenite in the skarn mineralization yielded a Re‒Os date of 510 ± 2 Ma, which is coeval with U‒Pb dates of columbite-tantalite from other regional pegmatites (515–509 Ma). Therefore, it is likely that pegmatite magmatism acted as the source of fluid and heat for the mineralization. The C–O stable isotope data for marbles and skarns are consistent with interaction of magmatic fluid and host marble at variable XCO₂ conditions. T-XCO₂ pseudosections define peak conditions of metamorphism/metasomatism at 650–600 °C over a wide range of XCO₂ (between 0.4 and 0.8), whereas the retrograde stage started at ~ 550 °C. Late garnet crystallization at low XCO₂ (&lt; 0.2) indicates high H₂O influx, while scapolite crystallization required high XCO₂ (~ 0.8). Together with the interpretation of textural relationships, these observations indicate that skarn and marble formation occurred under open-system conditions with fluctuating XCO₂ fluid composition as a consequence of magmatic fluid infiltration.</p>","PeriodicalId":18682,"journal":{"name":"Mineralium Deposita","volume":"16 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141768574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrological, geochemical and mineralogical characteristics of Wigu Hill carbonatite, Uluguru Mountains, Tanzania: insights into carbonatite evolution and REE mineralization","authors":"Mary Charles Moshi, Yasushi Watanabe, Nelson Boniface, Tatsuki Tsujimori, Carmela Tupaz, Daisuke Araoka, Shogo Aoki, Elisante E. Mshiu","doi":"10.1007/s00126-024-01295-y","DOIUrl":"https://doi.org/10.1007/s00126-024-01295-y","url":null,"abstract":"<p>The Wigu Hill Carbonatite, located south of Uluguru Mountain, is amongst the REE-endowed carbonatites in Tanzania. The carbonatite comprises apatite dolomite carbonatite that has been locally brecciated and intruded by small bodies of mica dolomite carbonatite. These early carbonatites are fine to medium grained, poorly enriched in REE₂O₃ (&lt; 0.4 wt%), and show elevated Nb (&gt; 200 ppm). The early carbonatites are crosscut by REE-bearing carbonatite dikes that host pegmatitic, well-preserved pseudomorphs after burbankite. The REE-bearing carbonatites are characterised by high REE₂O₃ (6–10 wt%), and pseudomorphs that vary in colour and mineralogy, reflecting the dissolution of primary burbankite through reaction with evolving carbothermal fluids in two major phases; (1) early altered burbankite formed yellow-colored pseudomorphs typified by an assemblage of synchysite-(Ce) with high (La/Ce)_N - (La/Nd)_N ratios, barite, Ca-strontianite, calcite, and quartz; and (2) subsequent late alterations by highly evolved fluids resulted into green and pink-colored pseudomorphs consisting of synchysite-(Ce) with low (La/Ce)_N - (La/Nd)_N ratios, barite, Ca-strontianite, fluorite, calcite, quartz, apatite, monazite, and Al-REE-phosphates. The stable C-O and Mg isotopes signatures of dolomite across Wigu Hill indicate a pristine mantle source (δ¹³C_VPDB -4.1‰ to -6.2‰; δ¹⁸O_VSMOW +6.5‰ to + 7.31‰ and δ²⁶Mg -0.44 to + 0.19‰), and are locally modified by surface processes which resulted in bastnaesite enriched zones with up to 15 wt% REE₂O₃. Textural, geochemical, and stable isotope data tracks a polygenetic evolution of Wigu Hill with the main REE mineralization phase occurring at the end of magmatic phase as a result of magmatic fractionations. Reworking by carbothermal fluids and locally by surface process has resulted in REE enrichment.</p>","PeriodicalId":18682,"journal":{"name":"Mineralium Deposita","volume":"88 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141768573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrogenesis of magmatic REE mineral occurrences near Jamestown, Colorado (U.S.A.)","authors":"Charles R. Stern, Shea Burnham, Andrew Kylander-Clark, Julien Allaz, Markus B. Raschke","doi":"10.1007/s00126-024-01291-2","DOIUrl":"https://doi.org/10.1007/s00126-024-01291-2","url":null,"abstract":"<p>Two magmatic REE-rich occurrences, located near Jamestown, Colorado, and hosted in the Precambrian Longs Peak granite batholith, exhibit unusual textures that suggest formation by fluoride-silicate melt immiscibility. Both contain small (&lt;2 mm diameter) globular F-, P-, and REE-rich segregations of fluorite and monazite-(Ce). In addition, the northern of the two localities preserves evidence of a second melt immiscibility event in the form of larger (up to several cm diameter) aplite-hosted globular segregations of fluorite and the REE minerals allanite-(Ce), monazite-(Ce), fluorbritholite-(Ce), törnebohmite-(Ce), and cerite-(Ce). The southern of the two localities lacks these cm-scale globular textures, but instead contains much larger aggregates of these same REE minerals, with up to &gt;57 wt. % ΣREE₂O₃, yet no fluorite, as well as large aggregates of allanite-(Ce) and quartz, and an amphibole-bearing REE-rich rock containing allanite-(Ce), other REE minerals, quartz and minor apatite. A new Nd-Sm laser ablation age of 1.422(24) Ga on monazite-(Ce) and allanite-(Ce) from the southern locality implies the same age of formation of 1.420(25) Ga as for the northern locality, with equally similar initial ε_Nd1.42Ga values of these REE minerals. A newly discovered third locality, containing primarily allanite-(Ce), minor monazite-(Ce), and thorite, without fluorite, extends the number, spatial distribution and total volume of these mineralogically unusual magmatic REE occurrences. We suggest that the REE were concentrated in these three localities by multiple stages of fluoride-silicate melt immiscibility. For the southern locality, slower cooling of a possibly larger magma volume, or in a deeper environment, allowed greater aggregation of the immiscibly separated REE-rich phases, as well as loss of the volatile element F, resulting in a greater availability of Ca accommodated by the crystallization of amphibole and minor apatite.</p>","PeriodicalId":18682,"journal":{"name":"Mineralium Deposita","volume":"39 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141597669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In-situ geochronology combined with geochemical and isotopic signatures record mineralization and fluid characteristics at the Xiaoxi’nancha porphyry Au-Cu deposit, NE China","authors":"Peng-Fei Shan, Ming-Jian Cao, Noreen J. Evans, Pete Hollings, Fred Jourdan, Le Wang, Ke-Zhang Qin","doi":"10.1007/s00126-024-01294-z","DOIUrl":"https://doi.org/10.1007/s00126-024-01294-z","url":null,"abstract":"<p>The Xiaoxi’nancha porphyry Au-Cu deposit is located in Yanbian, Jilin Province, NE China. Gold-Cu mineralization is mainly associated with chlorite-sericite alteration. The ⁴⁰Ar/³⁹Ar age of pre-mineralization hydrothermal biotite in potassic alteration defines a relatively well-defined cluster at ~ 111 Ma to 114 Ma with a total fusion age of 112.0 ± 0.3 Ma. <i>In-situ</i> secondary-ion mass spectrometry U-Pb dating of hydrothermal titanite occurring with chalcopyrite yielded an intercept age of 109.0 ± 2.4 Ma. The similarity between the biotite and titanite formation ages suggests a mineralization age of ~ 110 Ma. Chlorite, quartz and apatite coexist in equilibrium and are closely related to mineralization. The Al-in-chlorite geothermometer indicates a formation temperature of 236–351℃ (mean 309℃), and the quartz-apatite pair yielded an average formation temperature of 306℃. The <i>in-situ δ</i>³⁴S compositions of sulfide have restricted and slightly positive values (pyrite 2.3 to 3.9‰, chalcopyrite 1.6 to 3.8‰ and molybdenite 2.3 to 3.7‰). The fluid <i>δ</i>¹⁸O values, calculated assuming quartz-fluid equilibrium, vary from 2.4 to 5.5‰ (average = 4.0‰). Therefore, the ore-forming hydrothermal fluids were of moderate-temperature with predominantly magmatic characteristics. Apatite exhibits distinct variations in structure and composition, and slight variations in oxygen isotopic composition. The areas in apatite with dark BSE textures are characterized by lower <i>δ</i>¹⁸O values, Cl contents and temperatures and higher F contents, consistent with the result of water–rock interaction rather than mixing with meteoric water. The water–rock interaction and its resulting cooling, can reduce the metal solubility, likely triggering mineralization at Xiaoxi’nancha.</p>","PeriodicalId":18682,"journal":{"name":"Mineralium Deposita","volume":"49 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141566338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2D and 3D textures of sulfide ores from the Shitoukengde Ni-Cu sulfide deposit, East Kunlun Orogenic Belt, NW China: implications for the growth of orthopyroxene oikocrysts and formation of globular ores","authors":"Bo Wei, Christina Yan Wang, Yonghua Cao, Jiangze Wang","doi":"10.1007/s00126-024-01296-x","DOIUrl":"https://doi.org/10.1007/s00126-024-01296-x","url":null,"abstract":"<p>Orthopyroxene oikocrysts and globular ores are both observed in the Shitoukengde Ni-Cu sulfide deposit within the Eastern Kunlun Orogenic Belt in China. Through the utilization of microbeam X-ray fluorescence (micro-XRF) and electron probe micro-analyzer (EPMA) mapping techniques, complemented by 3D morphology analysis using high-resolution X-ray computed tomography (HRXCT), we conducted a comprehensive investigation into the 2D and 3D textures of orthopyroxene oikocrysts and globular ores in the Shitoukengde Ni-Cu sulfide deposit. The contents of orthopyroxene oikocrysts within the lherzolite gradually increases as it approaches the contact with coarse-grained orthopyroxenite. Both the orthopyroxene oikocrysts in the lherzolite and the cumulus orthopyroxene in the coarse-grained orthopyroxenite are centimeter-sized and contain corroded chadacrysts of olivine, exhibiting similar Cr-Al sector and oscillatory zoning. It indicates that the orthopyroxene oikocrysts rapidly grew in a dynamic and fluctuating magmatic environment, rather than in a static crystal mush. We propose that the orthopyroxene oikocrysts initially grew in a boundary layer between an olivine orthocumulate and an orthopyroxene-saturated magma. The orthopyroxene oikocrysts and olivine crystals were then entrained within a flowing magma and redeposited in their current location. Globular sulfides in the coarse-grained orthopyroxenite can reach sizes of up to one centimeter and are not accompanied by silicate caps. The particle size distribution (PSD) plots of the globular sulfides exhibit concave-up PSD curves, indicating that the larger sulfide droplets are likely formed through the coalescence of sulfide microdroplets. During postcumulus processes, the downward migration and coalescence of microdroplets within the interstitial framework of orthopyroxene cumulate lead to the formation of larger sulfide blebs. The coalesced sulfide blebs were then stranded in the pore spaces of the crystal mush due to the capillary effects, resulting in the formation of centimeter-sized globular sulfides. The morphology of coalesced sulfide droplets within orthopyroxene cumulate is influenced by the relative sizes of the sulfide blebs, pore bodies, and pore throats within the interstitial framework. This study proposed a cumulus origin for the orthopyroxene oikocrysts and highlights that the coarse-grained rocks facilitate the formation of the globular ores.</p>","PeriodicalId":18682,"journal":{"name":"Mineralium Deposita","volume":"21 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141566311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extent and survival of zoned pyroxene within intrusions hosting magmatic sulfides: Implications for zoned pyroxene as a prospectivity indicator","authors":"Louise Schoneveld, Stephen J. Barnes, Kirsi Luolavirta, Siyu Hu, Michael Verrall, Margaux Le Vaillant","doi":"10.1007/s00126-024-01292-1","DOIUrl":"https://doi.org/10.1007/s00126-024-01292-1","url":null,"abstract":"<p>Chromium-zoning patterns in pyroxene from the economically significant Ni-Cu sulfide deposits at Nova-Bollinger (Western Australia) and Kevitsa (Northern Finland) were investigated using XRF mapping, automated mineralogy, and EPMA analyses. At Nova-Bollinger, complex Cr-zoning patterns are found widely throughout the cumulus orthopyroxene and clinopyroxene within the Lower Intrusion, a small chonolith that hosts the vast extent of the sulfide mineralisation. Cumulus pyroxenes with visible sector and abrupt zonation patterns have been found up to 150 m vertically away from the massive sulfide ore. Complex zoning patterns are observed throughout the Kevitsa intrusion, in the form of strong oscillatory zoning in cumulus clinopyroxene and sector zoning in idiomorphic orthopyroxene oikocrysts. Kevitsa pyroxenes show varying degrees of hydration, leading to epitaxial replacement by amphibole. Cr zonation is visible through the early stages of this alteration, with preservation enabled by the presence of Cr-rich epitaxial amphibole; however, the remnant zoning is lost as the amphibole alteration progresses. Results suggest that Cr zonation in pyroxene may be an effective indicator of dynamic recharged conduits and therefore an indicator of favourable conditions for metal enriched magmatic sulfide ore formation. Such indicators have significant vertical extent from the ore body and can survive partial alteration, which makes them a useful tool for prospectivity assessment of drilled intrusions. Furthermore, our data show that there is potential for complexly zoned pyroxene to be used as an ex-situ prospectivity indicator in glacial till.</p>","PeriodicalId":18682,"journal":{"name":"Mineralium Deposita","volume":"43 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cassiterite and monazite U-Pb dating, and cassiterite geochemistry of the Shiganghe and Tiechang tin deposits in the Baoshan district (NW Yunnan), SW China","authors":"Dazhao Wang, Yuhang Liu, Chengbiao Leng, Shimin Zhen, Qianxin Wang, Xiaohang Song, Wenbin Jia","doi":"10.1007/s00126-024-01293-0","DOIUrl":"https://doi.org/10.1007/s00126-024-01293-0","url":null,"abstract":"<p>The Baoshan district in the southwestern Sanjiang Tethyan domain is an important part of the worldclass Southeast Asian tin (Sn) belt. However, the timing and controlling factors of Sn mineralization are poorly constrained. Here, we conducted laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb dating of cassiterite and monazite, and cassiterite trace element analysis on the Shiganghe and Tiechang Sn deposits (Baoshan district) to unravel the temporal evolution of the regional Sn mineralization. The U–Pb dating of two cassiterite samples from Shiganghe yielded Tera-Wasserburg lower intercept ages of 75.5 ± 3.9 Ma and 75.9 ± 4.8 Ma. U-Pb dating on cassiterite and the cogenetic monazite from Tiechang yielded 32.8 ± 1.3 Ma and 32.2 ± 1.0 Ma, respectively. These ages confirm both Late Cretaceous and Oligocene Sn mineralization events in the Baoshan district. Geological characteristics, and age and geochemical data of cassiterite indicate that Shiganghe is a quartz-vein-type Sn deposit, genetically related to the Late Cretaceous granite that intruded the Ordovician Zhibenshan pluton. Tiechang resembles distal skarn Sn deposits related to the ~ 32 Ma magmatism along the Chongshan shear zone. Tin mineralization in the Tengchong-Baoshan district occurred mainly from the Late Cretaceous to Oligocene, corresponding to the Neo-Tethyan subduction and the subsequent India–Asia continental collision.</p>","PeriodicalId":18682,"journal":{"name":"Mineralium Deposita","volume":"17 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141489627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural context of the Flatreef in the Northern Limb of the Bushveld Complex","authors":"J. A. N. Brits, D. F. Grobler, A. Crossingham, T. G. Blenkinsop, W. D. Maier","doi":"10.1007/s00126-024-01289-w","DOIUrl":"https://doi.org/10.1007/s00126-024-01289-w","url":null,"abstract":"<p>The Flatreef occurs at a depth of 700 m under the farm Turfspruit 241 KR in the Northern Limb of the Bushveld Complex. The Flatreef forms part of the Platreef of the Northern Limb, which contains magmatic rocks of the Rustenburg Layered Suite of the Bushveld Complex. The structure of the Flatreef is a flat-lying to gently westerly dipping monoclinal to open fold, 1 km wide and 6 km long. Distinctive features within the Flatreef include the development of cyclical magmatic layering with locally thickened pyroxenitic layers, and associated economically significant poly-metallic mineralisation. Geophysical evidence, exploration drill core, and recent underground exposure show that deformation had a major influence on the Flatreef mineralization. Block faulting and first generation folding affected the orientation and shape of the sedimentary host-rock sequence prior to intrusion of the Rustenburg Layered Suite. These structural and host-rock elements controlled the intrusion of the Lower Zone, and to a lesser degree, the Critical Zone correlatives of the Bushveld Complex in the Northern Limb. During intrusion reverse faults and shear zones and a second generation of folds were active, as well as local extension along layering. Syn-magmatic deformation on these structures led to laterally extensive stratal thickening across them, including the Merensky-Reef correlative that forms part of the Flatreef. This deformation was likely to have been driven by subsidence of the Bushveld complex. Many of these structures were intruded by granitic magmas during the late stages of intrusion, and they were reactivated during extension after intrusion. Thus, structures were active before, during and after the intrusion of Northern Limb, and the structural evolution determined the current geometry and mineral endowment of the Flatreef.</p>","PeriodicalId":18682,"journal":{"name":"Mineralium Deposita","volume":"28 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141453158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}