A new model for the optimal structural context for giant porphyry copper deposit formation

Porphyry-type deposits are the main global source of copper and molybdenum. An improved understanding of the most favorable structural settings for the emplacement of these deposits is necessary for successful exploration, particularly considering that most future discoveries will be made under cover based on conceptual target generation. A common view is that porphyry deposits are preferentially emplaced in pull-apart basins within strike-slip fault systems that favor local extension within a regional compressive to transpressive tectonic regime. However, the role of such a structural context in magma storage and evolution in the upper crust remains unclear. In this work, we propose a new model based on the integration of structural data and the geometry of magmatic-hydrothermal systems from the main Andean porphyry Cu-Mo metallogenic belts and from the active volcanic arc of southern Chile. We suggest that the magma differentiation and volatile accumulation required for the formation of a porphyry deposit is best achieved when the fault system controlling magma ascent is strongly misoriented for reactivation with respect to the prevailing stress field. When magmas and fluids are channeled by faults favorably oriented for extension (approximately normal to σ3), they form sets of parallel, subvertical dikes and veins, which are common both during the late stages of the evolution of porphyry systems and in the epithermal environment. This new model has direct implications for conceptual mineral exploration.

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Supplemental Material: A new model for the optimal structural context for giant porphyry copper deposit formation

10.1130/geol.s.13530653.v1 ◽

2021 ◽

Author(s):

Jose Piquer ◽

et al.

Keyword(s):

Porphyry Copper ◽

Copper Deposit ◽

Porphyry Copper Deposit ◽

Mineral Deposits ◽

Deposit Formation ◽

New Model ◽

Structural Context

Tables S1 and S2, a summary of all the relevant data from mineral deposits and active volcanic systems compiled for testing the model presented in this work.<br>

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Supplemental Material: A new model for the optimal structural context for giant porphyry copper deposit formation

10.1130/geol.s.13530653 ◽

2021 ◽

Author(s):

Jose Piquer ◽

et al.

Keyword(s):

Porphyry Copper ◽

Copper Deposit ◽

Porphyry Copper Deposit ◽

Mineral Deposits ◽

Deposit Formation ◽

New Model ◽

Structural Context

Tables S1 and S2, a summary of all the relevant data from mineral deposits and active volcanic systems compiled for testing the model presented in this work.<br>

Download Full-text

The history of mining and mineral exploration in Panama: From Pre-Columbian gold mining to modern copper mining

Boletín de la Sociedad Geológica Mexicana ◽

10.18268/bsgm2020v72n3a180720 ◽

2020 ◽

Vol 72 (3) ◽

pp. A180720

Author(s):

Stewart D. Redwood

Keyword(s):

Gold Mining ◽

Mineral Exploration ◽

Porphyry Copper ◽

Copper Deposit ◽

Gold Deposits ◽

Stream Sediment ◽

Gold Mine ◽

Foreign Companies ◽

Current Period ◽

History Of

The history of mining and exploration in Panama is a case study of the evolution of mining in a tropical, island arc environment in the New World from prehistoric to modern times over a period of ~1900 years. Panama has a strong mineral endowment of gold (~984 t), and copper (~32 Mt) resulting in a rich mining heritage. The mining history can be divided into five periods. The first was the pre-Columbian period of gold mining from near the start of the Current Era at ~100 CE to 1501, following the introduced of gold metalwork fully fledged from Colombia. Mining of gold took place from placer and vein deposits in the Veraguas, Coclé, Northern Darien and Darien goldfields, together with copper for alloying. Panama was the first country on the mainland of the Americas to be mined by Europeans during the Spanish colonial period from 1501-1821. The pattern of gold rushes, conquest and settlement can be mapped from Spanish records, starting in Northern Darien then moving west to Panama in 1519 and Nata in 1522. From here, expeditions set out throughout Veraguas over the next century to the Veraguas (Concepción), Southern Veraguas, Coclé and Central Veraguas goldfields. Attention returned to Darien in ~1665 and led to the discovery of the Espíritu Santo de Cana gold mine, the most important gold mine to that date in the Americas. The third period was the Republican period following independence from Spain in 1821 to become part of the Gran Colombia alliance, and the formation of the Republic of Panama in 1903. This period up to ~1942 was characterized by mining of gold veins and placers, and manganese mining from 1871. Gold mining ceased during World War Two. The fourth period was the era of porphyry copper discoveries and systematic, regional geochemical exploration programs from 1956 to 1982, carried out mainly by the United Nations and the Panamanian government, as well as private enterprise. This resulted in the discovery of the giant porphyry copper deposits at Cerro Colorado (1957) and Petaquilla (Cobre Panama, 1968), as well as several other porphyry deposits, epithermal gold deposits and bauxite deposits. The exploration techniques for the discovery of copper were stream sediment and soil sampling, followed rapidly by drilling. The only mine developed in this period was marine black sands for iron ore (1971-1972). The fifth and current period is the exploration and development of modern gold and copper mines since 1985 by national and foreign companies, which started in response to the gold price rise. The main discovery methods for gold, which was not analyzed in the stream sediment surveys, were lithogeochemistry of alteration zones and reexamination of old mines. Gold mines were developed at Remance (1990-1998), Santa Rosa (1995-1999 with restart planned in 2020) and Molejon (2009-2014), and the Cobre Panama copper deposit started production in 2019. The level of exploration in the country is still immature and there is high potential for the discovery of new deposits.

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A Comparative Study of Porphyry-Type Copper Deposit Mineralogies by Portable X-ray Fluorescence and Optical Petrography

Minerals ◽

10.3390/min10050431 ◽

2020 ◽

Vol 10 (5) ◽

pp. 431 ◽

Cited By ~ 1

Author(s):

Connor Gray ◽

Adrian Van Rythoven

Keyword(s):

Mineral Exploration ◽

Porphyry Copper ◽

Fluorescence Analysis ◽

Copper Deposit ◽

Porphyry Copper Deposits ◽

Rock Composition ◽

X Ray ◽

Core Logging ◽

Ore Minerals ◽

Optical Mineralogy

Porphyry-type deposits are crucial reserves of Cu and Mo. They are associated with large haloes of hydrothermal alteration that host particular mineral assemblages. Portable X-ray fluorescence analysis (pXRF) is an increasingly common tool used by mineral prospectors to make judgments in the field during mapping or core logging. A total of 31 samples from 13 porphyry copper deposits of the Western Cordillera were examined. Whole-rock composition was estimated over three points of analysis by pXRF. This approach attempts to capture the rapid and sometimes haphazard application of pXRF in mineral exploration. Modes determined by optical petrography were converted into bulk rock compositions and compared with those determined by pXRF. The elements S, Si, Ca, and K all were underestimated by optical mineralogy, and the elements Cu, Mo, Al, Fe, Mg, and Ti were overestimated by optical mineralogy when compared with pXRF results. Most of these porphyry samples occur in veined porphyritic quartz monzonite that is characteristic of these deposits. Sulfide and silicate vein stockworks are pervasive in most of the samples as well as dissemination of sulfides outwards from veinlets. Ore minerals present include chalcopyrite and molybdenite with lesser bornite. Chalcocite, digenite, and covellite are secondary. Potential sources of analytical bias are discussed.

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Exhumation and Preservation of Paleozoic Porphyry Cu Deposits: Insights from the Yandong Deposit, Southern Central Asian Orogenic Belt

Economic Geology ◽

10.5382/econgeo.4812 ◽

2021 ◽

Author(s):

Lin Gong ◽

Barry P. Kohn ◽

Zhiyong Zhang ◽

Bing Xiao ◽

Lin Wu ◽

...

Keyword(s):

Middle Jurassic ◽

Mineral Exploration ◽

Porphyry Copper ◽

Copper Deposit ◽

Orogenic Belt ◽

Central Asian Orogenic Belt ◽

Porphyry Copper Deposits ◽

Copper Deposits ◽

Central Asian ◽

Chinese Tianshan

Abstract Paleozoic porphyry copper deposits are generally much less common than their Mesozoic or Cenozoic counterparts, as they can be completely eroded in rapidly uplifting arcs. There are, however, some large Paleozoic porphyry copper deposits preserved worldwide, especially in the Central Asian orogenic belt, although the processes by which these ancient porphyry deposits were preserved are poorly constrained. The Carboniferous Yandong porphyry copper deposit was selected as a case study to resolve this issue using a combination of thermal history models derived from low-temperature thermochronology data and regional geologic records. Our results show that Yandong preserves a record of at least two episodes of cooling separated by a phase of mild Middle Jurassic reheating. These two cooling events included one major event, linked to the Qiangtang collision or northward motion of Tarim plate during the late Permian to Triassic, and one minor event, possibly related to the Lhasa collision or closure of Mongol-Okhotsk Ocean from the Middle Jurassic to Early Cretaceous, respectively. Tectonic quiescence and limited exhumation prevailed from the Late Cretaceous to Cenozoic in the Yandong area. Combining our results with regional geologic records, we propose that extensional tectonic subsidence, postmineralization burial, dry paleoclimatic conditions, and Cenozoic tectonic quiescence were key factors for the preservation of Yandong. This study demonstrates that anomalously old apatite fission track ages, integrated with age-elevation relationships, can have implications for mineral exploration strategies in the Chinese Tianshan orogens.

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