scholarly journals Porphyry-related high-sulfidation mineralization early in Central American Arc development: Cerro Quema deposit, Azuero Peninsula, Panama

2020 ◽  
Vol 72 (3) ◽  
pp. A260719
Author(s):  
José Perelló ◽  
Alfredo García ◽  
Robert A. Creaser
Keyword(s):  
Rapid Evolution ◽  
Leading Edge ◽  
Central American ◽  
Large Igneous Province ◽  
Land Bridge ◽  
High Sulfidation ◽  
Central American Arc ◽  
Quartz Veinlet ◽  
Age Range ◽  
North And South America

The 70.74 to 70.66 Ma age range for three molybdenite samples accompanying pyrite- and enargite-bearing assemblages effectively constrains an earliest Maastrichtian age for the high-sulfidation Au-Cu mineralization at Cerro Quema, Panama. The epithermal system was contemporaneous with emplacement of a composite dacite dome complex in a geotectonic setting transitional from mafic, primitive intraoceanic (Azuero Protoarc) to more evolved island arc magmatism (Azuero Arc), during initial construction of the Central American land bridge at the trailing edge of the Caribbean Large Igneous Province (CLIP). The molybdenite ages confirm the rapid evolution of the earliest stages of the Central American Arc, from subduction initiation at 75–73 Ma to arc maturation at 71 Ma. A porphyry connection is apparent at Cerro Quema and characterized by highly contorted, banded, and planar quartz-veinlet stockworks and sheeted zones in pyrophyllite- and sericite-bearing patchy-textured rock. These are cut by ledges of quartz, alunite, and dickite, which implies overprinting of the advanced argillic lithocap onto the underlying porphyry environment. Hydrothermal telescoping resulted from synmineralization uplift congruent with an actively emerging volcanic arc, which the Re-Os molybdenite dates accurately constrain at 71 Ma, presumably as a far-field effect of collision between the leading edge of the CLIP with parts of North and South America.

scholarly journals Reply to “Porphyry-related high-sulfidation mineralization early in Central American Arc development: Cerro Quema deposit, Azuero Peninsula, Panama” by Corral (2021)

2021 ◽  
Vol 73 (1) ◽  
pp. A101220
Author(s):  
José Perelló ◽  
Robert A. Creaser ◽  
Alfredo García
Keyword(s):  
Rapid Evolution ◽  
Sulfide Minerals ◽  
Central American ◽  
Geodynamic Setting ◽  
High Sulfidation ◽  
Arc Stability ◽  
Epithermal Mineralization ◽  
Genetic Interpretation ◽  
Central American Arc ◽  
Azuero Peninsula

Dear Editor, we thank Corral (2020) for his anticipated interest in our paper on the timing of the porphyry-related high-sulfidation epithermal mineralization at Cerro Quema in the Azuero peninsula of southwestern Panama. Our study, based on three Re-Os ages for molybdenite intimately associated with Cu-bearing sulfide minerals from the hypogene roots of the La Pava center (Figure 1), shows that the main event of high-sulfidation Cu mineralization took place during the earliest Maastrichtian at ~71 Ma. The reported ages, together with the geologic relationships described in our paper (Perelló et al., 2020), plus a series of regional geologic, structural, petrochemical, and geotectonic considerations, not only precisely date the porphyry-related nature of the Cerro Quema high-sulfidation mineralization, but are also significant in that they confirm the rapid evolution of the earliest stages of the Central American Arc – from subduction initiation at 75-73 Ma to arc stability and maturation at 71 Ma (e.g., Buchs et al., 2011a and references therein) – and place the mineralization in a regional geodynamic setting. Irrespective of the regional geologic arguments reiterated by Corral (2020) in support of his previous genetic interpretation (e.g., Corral et al., 2016) and to invalidate our conclusions, Corral´s real concern is the reliability of our molybdenite ages, which are much older than his preferred age of mineralization for Cerro Quema. We believe that many of the points raised by Corral (2020), including the regional and local geologic backgrounds of the deposit and the dated samples, were properly addressed in Perelló et al. (2020), and that it would be redundant to repeat them here. Additional petrochemical evidence in support can be found in Whattam and Stern (2015, 2020) and Whatam (2018).

scholarly journals Comment to "Porphyry-related high-sulfidation mineralization early in Central American Arc Development: Cerro Quema deposit, Azuero Peninsula, Panama" by Perelló et al., (2020)

2021 ◽  
Vol 73 (1) ◽  
pp. A121220
Author(s):  
Isaac Corral
Keyword(s):  
Genetic Model ◽  
Porphyry Copper ◽  
Regional Scale ◽  
Hydrothermal Fluids ◽  
Central American ◽  
Geochronological Data ◽  
Magmatic Arc ◽  
High Sulfidation ◽  
Central American Arc ◽  
Azuero Peninsula

The Cerro Quema Au-Cu deposit is hosted by a dacite dome complex of the Río Quema Formation, a Late Campanian-Maastrichtian volcano-sedimentary sequence of the Panamanian magmatic arc. Its formational age is constrained at ~49 Ma by field evidences, crosscutting relationships and 40Ar/39Ar geochronology (Corral et al., 2016, Corral, 2021). The recent molybdenite Re-Os dates by Perelló et al. (2020) claim that ore is spatially and temporally related to the host volcanic domes at ~71 Ma. After a thorough review of the geologic, geochemical and geochronological data from the Cerro Quema area, it is concluded that the Re-Os dates of Perelló et al. (2020) are not representative of the Cerro Quema formational age. Their proposed formational age at ~71 Ma is significantly older than the age of the host rock (~67 Ma). Furthermore, they invoke a previously unrecognized regional-scale magmatic event solely based on their molybdenite Re-Os dates. Instead, the Cerro Quema genetic model discussed here, in which magmatic-hydrothermal fluids derived from porphyry copper-like intrusions associated with the Valle Rico batholith produced the Au-Cu mineralization at ~49 Ma, is consistent with the geology, geochemistry and geochronology of the Azuero Peninsula.

Paleomagnetism and U–Pb geochronology of the Clarence Head dykes, Arctic Canada: orthogonal emplacement of mafic dykes in a large igneous province

2009 ◽  
Vol 46 (3) ◽  
pp. 155-167 ◽  
Author(s):  
Steven W. Denyszyn ◽  
Don W. Davis ◽  
Henry C. Halls
Keyword(s):  
Remanent Magnetization ◽  
High Arctic ◽  
Large Igneous Province ◽  
Dyke Swarm ◽  
Canadian High Arctic ◽  
The North ◽  
Igneous Province ◽  
The Difference ◽  
Age Range ◽  
Chemical Remanent Magnetization

The north–south-trending Clarence Head dyke swarm, located on Devon and Ellesmere Islands in the Canadian High Arctic, has a trend orthogonal to that of the Neoproterozoic Franklin swarm that surrounds it. The Clarence Head dykes are dated by the U–Pb method on baddeleyite to between 716 ± 1 and 713 ± 1 Ma, ages apparently younger than, but within the published age range of, the Franklin dykes. Alpha recoil in baddeleyite is considered as a possible explanation for the difference in ages, but a comparison of the U–Pb ages of grains of equal size from both swarms suggests that recoil distances in baddeleyite are lower than those in zircon and that the Clarence Head dykes are indeed a distinctly younger event within the period of Franklin magmatism. The Clarence Head dykes represent a large swarm tangential to, and cogenetic with, a giant radiating dyke swarm ∼800 km from the indicated source. The preferred mechanism for the emplacement of the Clarence Head dykes is the exploitation of concentric zones of extension around a depleting and collapsing plume source. While the paleomagnetism of most Clarence Head dykes agrees with that of the Franklin dykes, two dykes have anomalous remanence directions, interpreted to be a chemical remanent magnetization carried by pyrrhotite. The pyrrhotite was likely deposited from fluids mobilized southward from the Devonian Ellesmerian Orogeny to the north that used the interiors of the dykes as conduits and precipitated pyrrhotite en route.

The American Proteaceae

1998 ◽  
Vol 11 (4) ◽  
pp. 287 ◽  
Author(s):  
Ghillean T. Prance ◽  
Vanessa Plana
Keyword(s):  
South America ◽  
Molecular Data ◽  
Central American ◽  
General Distribution ◽  
South American ◽  
Land Bridge ◽  
Eastern Brazil ◽  
The Family ◽  
Single Genus ◽  
Morphological And Molecular Data

The American Proteaceae are outliers from the main centres of diversity of the family in Australia and South Africa. There are about 83 species in eight genera which all belong to the monophyletic subfamily Grevilleoideae. Three genera, Embothrium, Oreocallis and Lomatia, are placed in the tribe Embothrieae (sensu Johnson and Briggs), four Euplassa, Gevuina, Panopsis and Roupala in the Macadamieae and the single genus Orites in the Oriteae. There are five genera endemic to America and three also have species in Australia and New Guinea (Gevuina, Lomatia and Orites). The Proteaceae appear to have arrived in South America via two routes. The larger genera Euplassa, Panopsis and Roupala, which are all endemic to America and have a general distribution in northern South America and south-eastern Brazil, are derived from Gondwanaland before it separated from South America. The remaining genera are distributed either in temperate South America or in the high Andes and appear to have arrived more recently via the Australia–Antarctica–South American connection. Three of these genera have species in both regions. The centres of species diversity of Euplassa, Panopsis and Roupala fall outside hypothesised forest refugia, indicating that they are not true rainforest species but species of seasonal habitats like those achieved at higher altitudes where they are commonly found. Two genera,Panopsis and Roupala, have reached Central America after the central American land bridge was formed six million years ago. The exact relationship to genera on other continents is still unclear and there is a need for a cladistic biogeographic analysis of the group based on both morphological and molecular data.

scholarly journals Phylodynamics reveals extinction–recolonization dynamics underpin apparently endemic vampire bat rabies in Costa Rica

2019 ◽  
Vol 286 (1912) ◽  
pp. 20191527 ◽  
Author(s):  
Daniel G. Streicker ◽  
Silvia Lucia Fallas González ◽  
Giovanna Luconi ◽  
Rocío González Barrientos ◽  
Bernal Leon
Keyword(s):  
Costa Rica ◽  
Rabies Virus ◽  
Sequence Data ◽  
Disease Incidence ◽  
Field Studies ◽  
Central American ◽  
The North ◽  
North And South America ◽  
North And South ◽  
Vampire Bat

Variation in disease incidence in wildlife is often assumed to reflect environmental or demographic changes acting on an endemic pathogen. However, apparent endemicity might instead arise from spatial processes that are challenging to identify from traditional data sources including time series and field studies. Here, we analysed longitudinal sequence data collected from rabies virus outbreaks over 14 years in Costa Rica, a Central American country that has recorded continuous vampire bat-transmitted rabies outbreaks in humans and livestock since 1985. We identified five phylogenetically distinct lineages which shared most recent common ancestors with viruses from North and South America. Bayesian phylogeographic reconstructions supported bidirectional viral dispersals involving countries to the north and south of Costa Rica at different time points. Within Costa Rica, viruses showed little contemporaneous spatial overlap and no lineage was detected across all years of surveillance. Statistical models suggested that lineage disappearances were more likely to be explained by viral extinctions than undetected viral circulation. Our results highlight the importance of international viral dispersal for shaping the burden of rabies in Costa Rica, suggest a Central American corridor of rabies virus invasions between continents, and show that apparent disease endemicity may arise through recurrent pathogen extinctions and reinvasions which can be readily detected in relatively small datasets by joining phylodynamic and modelling approaches.

Sign in / Sign up

Export Citation Format

Share Document