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The sediment-hosted polymetallic (Pb, Zn, Ag, Au-Cu) mineralization of the Vale do Ribeira Mineral District has been known since the beginning of the 20th century, but exploration was interrupted just before the turn of the century. The Vale do Ribeira Mineral District is part of the Southern Ribeira Belt, developed during the Brasiliano-Pan African orogeny. Polymetallic mineralization is mainly hosted in metalimestones of the Lajeado Group, a typical platform carbonate sequence of a passive margin, which has been deformed during the Gondwana assembly. The region has a gap of research since the mines were closed, which justifies new projects on their mineral economic potential. Fieldwork, petrographic and geochemical analyses were developed in five currently inactive mines (Panelas, Barrinha, Rocha, Lajeado, and Furnas) and their surroundings, along with the description of a drill core executed in the 1980s. The main type of ore consists of polymetallic fault-fill veins of massive sulfide, which are composed essentially by argentiferous galena, sphalerite, pyrrhotite, arsenopyrite, and chalcopyrite. The highest ore grades were obtained from samples in the Panelas Mine, with contents of up to 35% lead, 5% zinc, > 1% copper and 564 ppm silver, as well as 23% iron. New ore occurrences were described in a secondary gallery of the Barrinha Mine, whose gold grades reached up to 5,630 ppb. The main controls of the mineralization are lithological - since the ore occurs exclusively in carbonate rocks, irrespective of the geological unit - and structural, related to NE high-angle strike-slip fault zones, including evidence of fault-valve behavior. Fault zones as the main control of the polymetallic veins is an innovative interpretation, increasing the perspectives for mineral exploration in the area. Although they are small deposits, the presented data indicate that the region has potential for new discoveries and that the mined deposits are probably not exhausted.

The Tethyan domain from China to Iran hosts many important sediment-hosted Pb–Zn deposits but most have been poorly documented. This study summarizes the salient features of these deposits and discusses the type of ore, tectonic setting, and important ore controls, on the basis of new geological observations and previous publications. The Tethyan domain is characterized by the young and extensive Himalayan–Tibetan and Zagros orogens that formed through collisions between the India/Arabia and Eurasia continents since the Late Cretaceous or early Cenozoic. Abundant Mississippi Valley-type (MVT) and subordinate clastic-dominated (CD, also known as SEDEX) Pb–Zn deposits occur in this domain, including in central and eastern Himalayan–Tibetan orogen in China, the Indian passive margin in southern Pakistan, and various tectonic units of Iran. Economically important deposits contain 0.1–21 Mt Pb + Zn and have total metal resources of ∼75 Mt with ∼48% being oxidized ores. All major deposits known in this domain are MVTs (i.e., the Jinding, Huoshaoyun, Mehdiabad, and Angouran deposits). Mississippi Valley-type Pb–Zn deposits occur in continental-collision-related fold-and-thrust belts and forelands, where deposits are mostly located on the margin of the Eurasian continent, with some in the Indian and Arabian continental margins. Clastic-dominated Pb–Zn deposits occur in central Iran and southern Pakistan, hosted by deep-water siliciclastic sequences of the early Cambrian rifted continental margin of Gondwana and the Jurassic passive continental margin of India, respectively. The youngest mineralized rocks and ages constrain that some important MVT deposits (e.g., the Jinding, Chaqupacha, and Angouran deposits) were formed after a main phase of regional compression, during a regional, large-scale strike-slip or crustal-extension stage in a continental collision setting. In sense of lithologic structure, important ore controls for MVT deposits include evaporite diapir structure, carbonate/evaporite dissolution–collapse structure, pre-existing barite, and porous dolostone. Much of the primary sulfide ore in this domain has been oxidized by supergene processes. This is particularly pronounced in the newly discovered Huoshaoyun deposit, where almost all sulfides have been oxidized to smithsonite and cerussite. An understanding of tectonic setting, ore controls, and supergene processes is essential in exploring for MVT deposits in this domain. Unlabelled Image • Abundant Mississippi Valley-type (MVT) deposits and minor clastic-dominated (CD) deposits • MVT deposits in continental collisional forelands and fold and thrust belts • MVT ore formations in a regional strike-slip or crustal-extension stage in a continental collision setting • MVT ore controls: evaporite diapir, carbonate/evaporite dissolution–collapse, pre-existing barite, and porous dolostone • Supergene process occurring in many sediment-hosted Zn–Pb deposits [ABSTRACT FROM AUTHOR]

Highlights • Similar mineralization and alteration occurs throughout the Punta del Cobre district. • Mineralization and alteration is lithologically controlled or structurally controlled. • Mineralization formed over a maximun period of 122–110 Ma. • Main mineralization event occurred before or close to 115 Ma. • Transpressional deformation was synchronous with batholith emplacement and mineralization. • Deformation enhanced local permeability of the host rocks. • Transpressional conditions might have enhanced the flow of basinal brines. • There is no field evidence for a discrete syn-main stage mineralization suite of intrusions. • Intrusions are relatively unreceptive hosts for mineralization. ABSTRACT The Candelaria-Punta del Cobre district is the largest Iron-Oxide Cu and Au (IOCG) district in the Chilean IOCG belt with more than 13 Mt of contained copper. Candelaria is the most important deposit in the district, which includes seven other smaller producers (Carola, Punta del Cobre, Mantos de Cobre, Candelaria Norte, Granate, Alcaparrosa, Atacama Kozan, Las Pintadas). The district, which is characterized by an Early-Cretaceous volcanic-sedimentary arc sequence (∼135–132 Ma; Punta del Cobre Formation) overlain by the marine-sedimentary Chañarcillo Group, formed in an extensional back-arc basin (∼132–130 Ma). The Copiapó batholith, which occupies the western side of the district, was emplaced between ∼118 and 110 Ma during the change from extensional to transpressional tectonics. Mineralization is hosted predominately in the upper part of the Lower Andesite member and the overlying Volcano-sedimentary and Dacite members all within the Punta del Cobre Formation. Mineralization is hosted by fault zones, breccias, and specific lithologies. North-northwest faults are the dominant host for vertically extensive orebodies. Stratigraphically-controlled mineralization forms extensive stratabound ore bodies ("mantos"). Textural evidence suggest that the hydrothermal system evolved and advanced upwards over time. The earliest event was dominated by magnetite-actinolite in stratigraphically-controlled mantos and extensive zones of disseminated magnetite-actinolite below Candelaria, which were subsequently overprinted by chalcopyrite-dominant mineralization with magnetite-actinolite-biotite-K-feldspar alteration. In addition to magnetite, iron oxides include widespread mushketovite and hematite in the upper part of some deposits. Geochronological data suggest that the main phase of mineralization occurred between ∼122 Ma and ∼115 Ma (U-Pb in zircon), overlapping in age with the two major early phases of the Copiapó batholith. There is no field evidence to indicate that exposed phases of the batholith were the source of mineralizing fluids. Alteration and mineralization in the earliest phase of the batholith (La Brea) occurs in structures and is minor compared to mineralization in the Punta del Cobre Formation. Later phases of the batholith cut the main stage of mineralization. The extent of IOCG mineralization in the Candelaria-Punta del Cobre district reflects a combination of factors including changing regional kinematics and related fault architecture, multiple intrusive events, fluid access to permeable and reactive lithologies, vertical changes in redox conditions, and the potential role of multiple fluids. [ABSTRACT FROM AUTHOR]

Abstract: The approach taken in this paper, namely synthesising a wealth of previous information with new data and a genetic model, in combination with integrated numerical analyses, led to new insights into the geological controls on the localisation of auriferous veins and residual prospectivity of the Charters Towers goldfield, NE Australia. The method also has implications for the assessment of other “mature” goldfields worldwide. Despite a number of different ore controls having operated within the Charters Towers goldfield, the controlling factors can be linked to a single genetic model for orogenic, granitoid-hosted lode-gold mineralisation in a brittle deformation regime (D4) of NE–SW to NNE–SSW shortening, under conditions of supralithostatic fluid pressure and low stress difference. Spatial autocorrelation results suggest district-scale alignment of the auriferous veins parallel to and overlapping with the ESE–WNW- to E–W-striking Charters Towers–Ravenswood lineament, a major crustal boundary in the basement to the Ravenswood batholith. At the camp-scale, auriferous veins have abundance and proximity relationships with NW–SE-, NNW–SSE-, NE–SW- and ENE–WSW-oriented lineaments, suggesting that structures that controlled gold deposition in one camp did not necessarily control mineralisation in other camps. Fractal dimensions obtained with the box-counting method range from 1.02 to 1.10, whereas veins in the Charters Towers City camp are characterised by a significantly higher fractal dimension of 1.28. This discrepancy may be taken to imply that most or all outcropping and near-surface deposits within the Charters Towers City camp have been found and that new discoveries are more likely to occur at greater levels of depth, or outside the boundaries of this camp. The new understanding has implications for the assessment of the residual prospectivity of the Charters Towers goldfield, where large areas of prospective rock types and structures (e.g., approximately 40% of the Charters Towers–Ravenswood lineament) are hidden under cover. This parameter space was inaccessible to the historic prospectors and has received relatively little attention from recent explorers. The following steps are suggested for the development of a targeting strategy for lode-gold exploration in areas of the goldfield under cover: (1) identify from geological and geophysical data the ENE–WSW (±15°) and NNW–SSE (±15°) striking structures and geological boundaries within a 20-km-wide corridor parallel to and centred upon the Charters Towers–Ravenswood lineament, the potential control on gold deposit distribution at the regional- to district-scale, (2) interpret from geological and geophysical data the distribution of pre-Middle Devonian granitoids within these areas that are the preferred host rocks of the payable gold deposits, (3) deduce from geophysical data the ENE–WSW (±15°) and NNW–SSE (±15°) striking structures that cut or bound the intrusions identified in step 2, (4) locate segments along the structures identified in step 3 that deviate most from the geometry of a straight line (e.g., potential bends or splays) and/or intersect other structures or geological contacts, or both, and (5) define and rank potential targets within the prospective areas identified in step 4 and systematically test the best ones. [Copyright &y& Elsevier]

Focuses on a study on the ore controls and depositional mechanisms in Carlin-type gold deposits. Fluid inclusion and phase equilibria of the deposits; Relation between gold grade and other mineralogical features in the deposits; Conclusion.