Discrimination of productive and nonproductive porphyritic intrusions in the Chilean Andes

Baldwin, Julia A.; Pearce, Julian A.

doi:10.2113/gsecongeo.77.3.664

Cited by 74 publications

(34 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This depletion is typical of a calcalkaline magmatism in a subduction zone environment. The Nb versus Y, and Rb versus Y+Nb diagrams (figure 20) further confirm that the Karakoram granitoids are both volcanic arc granites (VAG) and syn-collision granites (Syn-COLG), hence comparing to the continental arc plutonism of the Chile arc [32].…”

Section: Geochemistry' Of the Tirit Granitoidsmentioning

confidence: 55%

Tectonic and magmatic evolution of the eastern Karakoram, India

Upadhyay

Sinha²,

Chandra³

et al. 1999

Geodinamica Acta

View full text Add to dashboard Cite

-The Shyok suture zone separates the Ladakh terrane to the SW from the Karakoram terrane to the NE. Six tectonic units have been distinguished. From south to north these are: 1. Saltoro formation; 2. Shyok volcanites; 3. Saltoro molasse; 4. Ophiolitic melange; 5. Tirit granitoids; 6. Karakoram terrane including the Karakoram batholith. Albian-Aptian Orbitolina-bearing limestones and turbidites of the Saltoro formation tectonically overlie high-Mg-tholeiites similar to the tectonically overlying Shyok volcanites. The high-Mg tholeiitic basalts and calcalkaline andesites of the Shyok voicanites show an active margin signature. The Saltoro molasse is an apron-like, moderately folded association of redgreen shales and sandstones that are interbedded with -50 m porphyritic andesite. Desiccation cracks and rain-drop imprints indicate deposition in a subaerial fluvial environment. Rudist fragments from a polygenic conglomerate of the Saltoro molasse document a post-Middle Cretaceous age. The caicalkaline andesites of the Shyok volcanites are intruded by the Tirit granitoids, which are located immediately south of the Ophiolitic melange and belong to a weakly deformed trondhjemite-tonalite-granodiorite-granite suite. These granitoids are subalkaline, I-type and were emplaced in a volcanic arc setting. The subalkaline to calcalkaline granitoids of the Karakoram batholith are I-and S-type granitoid. The I-type granitoids represent a typical calcalkaline magmatism of a subduction zone environment whereas the S-type granitoids are crustderived, anatectic peraluminous granites. New data suggest that the volcano-plutonic and sedimentary successions of the Shyok suture zone exposed in northern Ladakh are equivalent to the successions exposed along the Northern suture in Kohistan. It is likely that the Kohistan and Ladakh blocks evolved as one single tectonic domaiñ uring the Cretaceous-Palaeogene. Subsequently, collision, suturIng and accretion of the Indian plate along the Indus suture (50-60 Ma) together with tectonic activity along the Nanga ParbatHaramosh divided Kohistan and Ladakh into two arealy distinct magmatic arc terranes. The activity and a dextral offset along the

show abstract

Section: Geochemistry' Of the Tirit Granitoidsmentioning

confidence: 55%

Tectonic and magmatic evolution of the eastern Karakoram, India

Upadhyay

Sinha²,

Chandra³

et al. 1999

Geodinamica Acta

View full text Add to dashboard Cite

show abstract

“…Here, we focus on geochemical data for Cu-bearing porphyries associated with the subduction of oceanic crust that formed during two major phases of metallogenesis in the eastern Pacific. The first phase, in the Late Cretaceous-Paleogene, was associated with the formation of the Laramide porphyry province in Arizona (e.g., Lang and Titley, 1998), the Mezcala porphyry province in Mexico (e.g., González-Partida et al, 2003), the El Salvador deposit in the Chilean Porphyry Cu belt (e.g., Baldwin and Pearce, 1982), and the Bingham mining district in Utah (e.g., Stavast et al, 2006).…”

Section: Temporal and Spatial Distribution Of Porphyry Depositsmentioning

confidence: 99%

“…The CPEPR deposits are generally associated with diorite, granodiorite, quartz diorite, quartz monzonites, and granite (e.g., Baldwin and Pearce, 1982;Lang and Titley, 1998;González-Partida et al, 2003). In contrast, the majority of the MPEPR deposits are associated with andesite, monzodiorite, granodiorite, quartz diorites, monzonite and dacite (e.g., Müller and Forrestal, 1998;Reich et al, 2003;Cannell et al, 2005;Schutte et al, 2010;Stern et al, 2010;Vry et al, 2010).…”

Section: Major and Trace Element Geochemistrymentioning

confidence: 99%

Geochemical differences between subduction- and collision-related copper-bearing porphyries and implications for metallogenesis

Chen

Wang

et al. 2015

Ore Geology Reviews

View full text Add to dashboard Cite

Porphyry Cu (-Mo-Au) deposits occur not only in continental margin-arc settings (subduction-related porphyry Cu deposits, such as those along the eastern Pacific Rim (EPRIM)), but also in continent-continent collisional orogenic belts (collision-related porphyry Cu deposits, such as those in southern Tibet). These Cu-mineralized porphyries, which develop in contrasting tectonic settings, are characterized by some different trace element (e.g., Th, and Y) concentrations and their ratios (e.g., Sr/Y, and La/Yb), suggesting that their source magmas probably developed by different processes. Subduction-related porphyry Cu mineralization on the EPRIM is associated with intermediate to felsic calc-alkaline magmas derived from primitive basaltic magmas that pooled beneath the lower crust and underwent melting, assimilation, storage, and homogenization (MASH), whereas K-enriched collision-related porphyry Cu mineralization was associated with underplating of subduction-modified basaltic materials beneath the lower crust (with subsequent transformation into amphibolites and eclogite amphibolites), and resulted from partial melting of the newly formed thickened lower crust. These different processes led to the collision-related porphyry Cu deposits associated with adakitic magmas enriched by the addition of melts, and the subduction-related porphyry Cu deposits associated with magmas comprising all compositions between normal arc rocks and adakitic rocks, all of which were associated with fluid-dominated enrichment process.In subduction-related Cu porphyry magmas, the oxidation state (fO 2 ), the concentrations of chalcophile metals, and other volatiles (e.g., S and Cl), and the abundance of water were directly controlled by the composition of the primary arc basaltic magma. In contrast, the high Cu concentrations and fO 2 values of collision-related Cu porphyry magmas were indirectly derived from subduction modified magmas, and the large amount of water and other volatiles in these magmas were controlled in part by partial melting of amphibolite derived from arc basalts that were underplated beneath the lower crust, and in part by the contribution from the rising potassic and ultrapotassic magmas. Both subduction-and collision-related porphyries are enriched in potassium, and were associated with crustal thickening. Their high K 2 O contents were primarily as a result of the inheritance of enriched mantle components and/or mixing with contemporaneous ultrapotassic magmas.

show abstract

“…On the contrary, Wang et al (2007), for instance, suggest a fO 2 reduction by slab melts below South America. Then it might be suggested that some of the preferential associations observed between certain adakitic magmas and major gold deposits (e.g., [Baldwin and Pearce, 1982], [Thiéblemont et al, 1997], [Sajona and Maury, 1998], [Gonzalez-Partida et al, 2003], [Levresse et al, 2004] and [Rae et al, 2004]) may be related to a greater availability of gold in the magma source(s).…”

Section: Importance Of Intensive Parameters and Magma Sourcementioning

confidence: 99%

“…The existence of a link between economic deposits and alkaline arc magmas has been demonstrated in Papua-New Guinea (Richards, 1990). In other cases, a preferential relationship has been noted between adakitic magmatism and Au-Ag-Cu-Mo epithermal and porphyry deposits ( [Baldwin and Pearce, 1982], [Thiéblemont et al, 1997], [Sajona and Maury, 1998], [Gonzalez-Partida et al, 2003], [Levresse et al, 2004] and [Rae et al, 2004]), although such an association remains doubtful to some authors (e.g., Richards and Kerrich, 2007). The origin of a potential connection between adakitic magmas and epithermal and porphyry-type deposits is the central question addressed in this paper.…”

Section: Introductionmentioning

confidence: 98%

Controls on gold solubility in arc magmas: An experimental study at 1000°C and 4kbar

Jégo

Pichavant

Mavrogenes

2010

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

In order to (1) explain the worldwide association between epithermal gold-coppermolybdenum deposits and arc magmas and (2) test the hypothesis that adakitic magmas would be Au-specialized, we have determined the solubility of Au at 4 kbar and 1000 °C for three intermediate magmas (two adakites and one calc-alkaline composition) from the Philippines. The experiments were performed over a fO 2 range corresponding to reducing ( NNO−1), moderately oxidizing ( NNO+1.5) and strongly oxidizing ( NNO+3) conditions as measured by solid Ni-Pd-O sensors. They were carried out in gold containers, the latter serving also as the source of gold, in presence of variable amounts of H 2 O and, in a few additional experiments, of S. Concentrations of Au in glasses were determined by LA-ICPMS. Gold solubility in melt is very low (30-240 ppb) but increases with fO 2 in a way consistent with the dissolution of gold as both Au 1+ and Au 3+ species. In the S-bearing experiments performed at NNO−1, gold solubility reaches much higher values, from 1200 to 4300 ppb, and seems to correlate with melt S content. No systematic difference in gold solubility is observed between the adakitic and the non-adakitic compositions investigated. Oxygen fugacity and the sulfur concentration in melt are the main parameters controlling the incorporation and concentration of gold in magmas. Certain adakitic and non-adakitic magmas have high fO 2 and magmatic S concentrations favorable to the incorporation and transport of gold. Therefore, the cause of a particular association between some arc magmas and Au-Cu-Mo deposits needs to be searched in the origin of those specialized magmas by involvement of Au-and S-rich protoliths. The subducted slab, which contains metal-rich massive sulfides, may constitute a potentially favorable protolith for the genesis of magmas specialized with respect to gold.

show abstract

Discrimination of productive and nonproductive porphyritic intrusions in the Chilean Andes

Cited by 74 publications

References 10 publications

Tectonic and magmatic evolution of the eastern Karakoram, India

Tectonic and magmatic evolution of the eastern Karakoram, India

Geochemical differences between subduction- and collision-related copper-bearing porphyries and implications for metallogenesis

Controls on gold solubility in arc magmas: An experimental study at 1000°C and 4kbar

Contact Info

Product

Resources

About