Geological and structural setting, age, and geochemistry of the orogenic gold deposits at the Pataz Province, Eastern Andean Cordillera, Peru

Haeberlin, Yves

doi:10.13097/archive-ouverte/unige:223

Cited by 6 publications

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“…(Figures 15 and 16) independent of any stratigraphic or regional order. Considering the palaeocurrent and the compositional data, a local provenance can generally not be derived from our data, with the exception of some samples in the Ricran, Paucartambo and Lagcha sections of central Peru (Figures 3 and 4) which indicate a derivation from the Young Marañon metamorphic Complex and the Ordovician volcanic Vijus Formation (Figure 16; Cardona et al, 2009;Haeberlin, 2001;Wiemer et al, 2021).…”

Section: Sedimentary Basin Fill and Provenance Of The Mitu Groupmentioning

confidence: 74%

“…of the Young Marañon Complex (Cardona et al, 2009;Wiemer et al, 2021). Early Famatinian volcanic rocks of the Vijus Formation (Haeberlin, 2001) east of the Marañon Complex may also have contributed to the respective detrital zircon age peak in the red group of samples (Figures 15 and 16).…”

Section: Multidimensional Scaling Analysis (Mds) and Interpretation O...mentioning

confidence: 99%

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Sedimentology, geochronology and provenance of the late Permian and Triassic Mitu Group in Peru—The evolution of continental facies along a transform margin

Panca,

Bahlburg,

Cárdenas

et al. 2024

Basin Research

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In the late Permian and Triassic, the continental Mitu Group formed in extensional basins along the length of the Cordillera Oriental and Altiplano of present‐day Peru. Given the presence of coeval arc systems only in northern Chile and southern Ecuador but not in Peru the tectonic setting of the Mitu basin has been interpreted variably as orthogonal continental rift, sinistral transtensional rift, aulacogen and back‐arc basin. The Mitu Group comprises continental mass flow and alluvial fan, fluvial, aeolian and minor lacustrian facies and hosts thick piles of subalkaline and alkaline intermediate and felsic ignimbrites and mafic lavas. The age of the Mitu Group had originally been established as ranging from the Late Permian to the late Triassic on the basis of structural considerations and scarce biostratigraphic data. Recently, U–Pb zircon ages from ignimbrites and sedimentary rocks have been taken to constrain the Mitu Group to the Middle and Late Triassic. We performed a sedimentological, heavy mineral, and zircon geochronological and Lu‐Hf isotope study of the Mitu Group in 14 sections mainly in southern and central Peru, and one section in northern Peru. Ten new U–Pb concordia ages on ignimbrites intercalated in the Mitu Group successions offer a new robust stratigraphic framework and constrain the stratigraphy of the Mitu Group between 260 and 205 Ma. In combination with maximum likelihood ages of deposition derived from detrital zircon, U–Pb geochronology places the deposition of the Mitu Group between ca. 270 and 194 Ma (lower Guadalupian into the Sinemurian). Detrital zircon U–Pb age distributions and heavy mineral assemblages reflect a strongly recycled Precambrian Amazonian and Palaeozoic proto‐Andean provenance. The Palaeozoic detrital age patterns are highly variable, and temporally and spatially random. A local provenance can generally not be identified. εHf(t) values in zircon obtained from ignimbrites and sedimentary rocks indicate variable degrees of crustal recycling. In the course of the Palaeozoic, εHf(t) values become on average progressively less negative, with a large proportion particularly of Mitu age zircons' εHf(t) values encompassing less evolved and moderately juvenile compositions. Along strike of the basin stratigraphic thicknesses, and rates and times of accumulation vary strongly with larger thicknesses and rates being registered in southern Peru. This suggests that the Mitu basin had been divided into a number of subbasins with individual histories of subsidence, accumulation, and volcanism. Absent a magmatic arc, late Permian–Triassic Peru evolved in a sinistral plate tectonic and regional framework expressed particularly in the sinistral Late Gondwanide orogeny predating the Mitu Group. We interpret that a sinistral transform fault linked the subduction zones in southern Ecuador and northern Chile and that the Mitu Group basin has formed by sinistral transtensional and transpressional movements along a related transcurrent fault inboard of the transform margin. In the broader framework of the accretionary Terra Australis orogen along the western Gondwana margin, this interpretation fits its evolution in the Andean segment in an internally consistent way.

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Section: Sedimentary Basin Fill and Provenance Of The Mitu Groupmentioning

confidence: 74%

Section: Multidimensional Scaling Analysis (Mds) and Interpretation O...mentioning

confidence: 99%

Sedimentology, geochronology and provenance of the late Permian and Triassic Mitu Group in Peru—The evolution of continental facies along a transform margin

Panca,

Bahlburg,

Cárdenas

et al. 2024

Basin Research

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Separate lead isotope analyses of leachate and residue rock fractions: implications for metal source tracing in ore deposit studies

Chiaradia

Fontboté

2003

Miner Deposita

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ARTICLEMassimo Chiaradia AE Lluı´s FontboteŚ eparate lead isotope analyses of leachate and residue rock fractions: implications for metal source tracing in ore deposit studies Abstract Separate lead isotope analyses of leachate and residue fractions are applied to a broad spectrum of rocks commonly investigated in metallogenic studies. Resulting data highlight a systematic behavior of leachate and residue fractions with respect to lead isotope compositions, which essentially depends on the mineralogical composition of the rock. Granitoid and high-grade metamorphic rocks have residue compositions virtually identical to common lead. In contrast, low-grade metasedimentary rocks may have residue compositions swamped by radiogenic lead of leach-resistant zircons. Mafic magmatic rocks have residues that are often more radiogenic than leachates, depending on the ratio of leach-refractory zircons to common lead in the residual fraction of these rocks. Separate leachate and residue analyses of source rocks provide two lead isotope end members whose mixture may represent lead with the appropriate ore fluid composition. Our leaching experiments indicate that hot acid solutions (and by inference hydrothermal fluids) preferentially leach radiogenic lead from medium-to high-grade metamorphic and granitoid rocks, whereas they preferentially leach common lead from low-grade metasedimentary and mafic magmatic rocks. The method presented in this study provides a reliable alternative to other methods (i.e., age-correction of bulk-rock compositions) for the determination of the common lead signature of felsic to intermediate magmatic rocks. This may be preferable to age-corrected bulk-rock analyses, where ages to apply for corrections of bulk-rock data are not known or where moderately to highly altered rocks must be used. Case studies of orogenic gold and MVT districts of Peru (Pataz and San Vicente, respectively) show that separate leachate and residue lead isotope analyses carried out systematically on whole rocks allow a more thorough evaluation of metal source reservoirs than does the standard method of age-corrected or uncorrected bulk-rock analyses.

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Councils¹,

Caffarey²

2019

2019 Ninth International Conference on Intelligent Computing and Information Systems (ICICIS)

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Geological and structural setting, age, and geochemistry of the orogenic gold deposits at the Pataz Province, Eastern Andean Cordillera, Peru

Cited by 6 publications

References 0 publications

Sedimentology, geochronology and provenance of the late Permian and Triassic Mitu Group in Peru—The evolution of continental facies along a transform margin

Sedimentology, geochronology and provenance of the late Permian and Triassic Mitu Group in Peru—The evolution of continental facies along a transform margin

Separate lead isotope analyses of leachate and residue rock fractions: implications for metal source tracing in ore deposit studies

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