SHRIMP U–Pb zircon geochronology and thermal modeling of multilayer granitoid intrusions

Alvarado, Juan Díaz; Fernández, Carlos; Castro, Antonio; Moreno‐Ventas, I.

doi:10.1016/j.lithos.2013.05.006

Cited by 39 publications

(11 citation statements)

References 68 publications

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“…Taking into account the compositional and textural features shown above, it may be inferred that the ages between 309 and 297Ma (average=300±4Ma) calculated for Group-I uraninite display the age of magmatic uraninite crystallization. This age overlaps with zircon ages (309 to 303Ma) from granites surrounding Los Santos skarn (Bea et al, 2004;Díaz Alvarado et al, 2013;Gutiérrez-Alonso et al, 2011;Valle Aguado et al, 2005;Zeck et al, 2007).…”

Section: The Significance Of the Chemical Uraninite Ages From Los Sansupporting

confidence: 61%

“…The tectono-metamorphic evolution of the northern half of the CIZ includes four main phases of ductile deformation (Díaz-Alvarado et al, 2013 and references therein): D 1 (upright and E-vergent folds coupled with contractional deformation), ~360-337Ma; D 2 (extensional detachments), ~337-316Ma; D 3 (upright folds and a new extensional episode), ~316-300Ma; and D 4 (upright folds and shear bands only described for the eastern part of the Spanish Central System (SCS)). Dating of zircon from Variscan granitoids reveals that most magmatism in the western part of the SCS occurred during the D 3 phase (309 to 303Ma) (Bea et al, 2004;Díaz Alvarado et al,…”

Section: Geological Settingmentioning

confidence: 99%

“…Mineralization of the 300-275Ma age group is related to a reorganization of the plate movement between Gondwana and Laurussia, Vindel et al (1995) and Tornos et al (2000) (1) (2) (4) (5); Martín-Crespo et al (2004) (3); and Martín-Crespo et al (2002) (6). The ages of granodiorites are from Orejana et al (2012) andDíaz Alvarado et al (2013). All Rb-Sr ages were recalculated using the decay constant recommended by IUGS (Villa et al, 2015).…”

Section: Late-variscan Hydrothermal Mineralizationmentioning

confidence: 99%

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Late-Variscan multistage hydrothermal processes unveiled by chemical ages coupled with compositiona.

Timón-Sánchez

Moro

Romer³

et al. 2019

GACTA

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The scheelite skarn from Los Santos and the W-Au veins from El Cabaco district, located in the Spanish Central System Batholith (SCSB), are some of the best-known tungsten ore deposits in Spain. Uraninite is an accessory mineral in both deposits, which underwent several hydrothermal flow events. Chemical and textural characteristics as well as electron microprobe U-Th-Pb uraninite chemical data from the different stages of the skarn and the vein-type mineralizations are presented here. Based on these data the uraninite was able to be classified into two groups. Group I uraninite has an octahedral habit and occurs as inclusions in K-feldspar relicts of the leucogranite related to Los Santos skarn formation. It shows high Th (6.95 to 8.51wt.% ThO 2) and high Rare Earth Elements (REEs) contents (0.55 to 1.38wt.% ∑REE 2 O 3). Group II uraninite occurs i) associated to El Cabaco granite, in a greenish selvage-style greisen and its reddish envelope and in the mineralized rimming quartz veins and ii) in Los Santos high temperature endoskarn and anorthite skarn, where it is associated with U-rich mica. This uraninite type has lower Th and ∑REE 2 O 3 contents than Group-I uraninite. The mineral chemistry and the assemblage and textural relationships suggest that Group-I uraninite is magmatic and the attained U-Th-Pb chemical age of 300±4Ma is interpreted as the magmatic age of the skarn-forming aplite granites in the western part of the SCSB. Group-II uraninite includes two events: i) a hydrothermal uraninite, which yields an age of 295±2Ma, dates a strong-alkali mobilization and early tungsten deposition and ii) a later hydrothermal processes, around 287±4Ma, that resulted in sulfides and late scheelite precipitation and widespread silicification. Finally, the gold deposition is younger than this silicification according to textural criteria. Therefore, W-Au deposits in the western part of the SCSB were formed by superposition of several processes that took place some 15Ma after the skarn-forming granite crystallized. Comparable W, W-Au and U deposits in the Variscan orogenic belt show a similar timing of hydrothermal events, suggesting that the hydrothermal history was controlled by large-scale Late-Variscan tectonic processes. Uraninite. U-Pb dating. W-Au deposits. Spanish Central System Batholith. Variscan belt.

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Section: The Significance Of the Chemical Uraninite Ages From Los Sansupporting

confidence: 61%

Section: Geological Settingmentioning

confidence: 99%

Section: Late-variscan Hydrothermal Mineralizationmentioning

confidence: 99%

See 1 more Smart Citation

Late-Variscan multistage hydrothermal processes unveiled by chemical ages coupled with compositiona.

Timón-Sánchez

Moro

Romer³

et al. 2019

GACTA

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“…The hypotheses that support rather continuous magmatic activity are mainly derived from the combined interpretation of radiometric ages of granitoids obtained by different methods 40 Ar- 39 Ar, K-Ar; e.g., Serrano Pinto et al, 1987;Díaz Alvarado et al, 2013;Martínez Catalán et al, 2014) and the numerical modeling of the thermal evolution of the orogen, including radioactive heat production (e.g., Bea et al, 1999Bea et al, , 2003Bea, 2012;Alcock et al, 2015). In essence, these hypotheses view melt production in the collisional scenario mainly as the result of severe crustal thickening of a fertile (graywacke and pelite rich) crust followed by an interval of thermal relaxation (e.g., Martínez-Catalán et al, 2014) accompanied by melting of the thickened crust.…”

Section: Introductionmentioning

confidence: 99%

Exhuming a cold case: The early granodiorites of the northwest Iberian Variscan belt—A Visean magmatic flare-up?

et al. 2018

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In this study we report laser ablation-inductively coupled plasma-mass spectrometer U-Pb ages of granitoids from the so-called early granodiorites of the northwest Iberian Variscan belt. The U-Pb results attest to significant magmatic activity in Visean time (ca. 347-337 Ma) that generated a hitherto poorly constrained granitoid suite in the northwest Iberian tract of the western European Variscan belt realm. This early Carboniferous suite (ECS) is mainly composed of peraluminous cold and hot crustal granodiorites and monzogranites with minor associated mafic rocks that attest to minor involvement of mantle melting. Based on the geochronological and geochemical data, we compare the Visean granitoids with younger Variscan granitoids in northwest Iberia and, in view of the tectonothermal scenarios of the Variscan collision in northwest Iberia, propose a model for the genesis of the ECS in northwest Iberia that involves rapid melting upon fast exhumation of the thickened Gondwanan crust in the course of the protracted Variscan collision.

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“…The Gredos batholith has been revealed during the last decade as one of the most outstanding and voluminous granitic exposures (more than 300 km in length and 60 km in width) to explore the interactions between intrusive magmas and a medium-to highgrade crustal sections. The batholith is mainly composed of Bt ±Crd granodiorites and monzogranites and minor amounts of basic rocks [Scarrow et al, 2009] that depict a Krich calc-alkaline suite characteristic of I-type post-collisional batholiths [Castro, 2019], emplaced during late D2 and D3 Variscan phases (320-290 Ma) [Díaz Alvarado et al, 2013;Díaz-Alvarado et al, 2011]. Detailed studies of the central area of the batholith have evidenced a laminar structure formed by mostly migmatitic host-rocks and intrusive layers.…”

Section: Field Relations Supporting Assimilation and Magma Contaminationmentioning

confidence: 99%

Magma differentiation and contamination: Constraints from 2 experimental and field evidences

Castro¹,

Rodríguez²,

Díaz‐Alvarado³

et al. 2020

Preprint

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Differentiation and contamination of silicic magmas are common phenomena characterizing the granite batholiths and large igneous provinces that build up most of the continental crust. Although they can be identified by means of geochemical relations of igneous rocks exposed in the continents, the mechanisms allowing magmas to undergo the necessary crystal-liquid separation and digestion of country rocks for differentiation and contamination are poorly constrained. In this paper we show two independent approaches that are essential to understand fractionation and contamination of magmas. These are (1) the study and interpretation of field relations in exposed deep sections of batholiths, and (2) the results of laboratory experiments carried out at middle-upper crust pressure. Experiments support that fractionation is intrinsic to crystallization of water-bearing magmas in thermal boundary layers created at the sidewalls of ascent conduits and walls of magma chambers. Gravitational collapse and fluid migration are processes identified in experimental capsules. Similarly, reaction experiments in mixed capsules support reactive bulk assimilation as a plausible mechanism that is compatible with field and petrographic observations in contaminated granitic rocks.

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SHRIMP U–Pb zircon geochronology and thermal modeling of multilayer granitoid intrusions

Cited by 39 publications

References 68 publications

Late-Variscan multistage hydrothermal processes unveiled by chemical ages coupled with compositiona.

Late-Variscan multistage hydrothermal processes unveiled by chemical ages coupled with compositiona.

Exhuming a cold case: The early granodiorites of the northwest Iberian Variscan belt—A Visean magmatic flare-up?

Magma differentiation and contamination: Constraints from 2 experimental and field evidences

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