Textural and Mineralogical Record of Low Pressure Melt Extraction and Silicic Cumulate Formation in the late Miocene Risco Bayo-Huemul Plutonic Complex, Southern Andes

Schaen, Allen; Singer, Brad S.; Cottle, John M.; Garibaldi, Nicolás; Schoene, Blair; Satkoski, Aaron M.; Fournelle, John

doi:10.1093/petrology/egy087

Cited by 16 publications

(58 citation statements)

References 113 publications

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“…The crystallization sequences inferred from textural observations and our estimates of interstitial volume loss are consistent with the observations of Schaen et al (). The quartz monzonite shows early crystallization of plagioclase followed by K‐feldspar, and late crystallization of interstitial quartz, plagioclase, and K‐feldspar.…”

Section: Discussionsupporting

confidence: 91%

“…At this location, the cavities are vertically elongate, up to 2 cm in length, and filled with subcentimeter euhedral K‐feldspar, quartz, tourmaline, and fluorite. The presence of miarolitic cavities records the exsolution of volatile phases from melt and supports the shallow emplacement depth (3–7 km) indicated by Al‐in‐Hbl barometry throughout the complex (Nelson et al, ; Schaen et al, ).…”

Section: Huemul Domainssupporting

confidence: 63%

“…In contrast, SPO on samples collected near the contacts (RB1503CB and RB1516) show some heterogeneity, possibly associated with conditions local to the edge of the intrusion (e.g., faster cooling rates and local flow dynamics). The euhedral feldspar alignment is interpreted as a record of transient melt flow associated with rhyolitic melt extraction (Schaen et al, ). The strong alignment of euhedral feldspars parallel to magnetic lineations indicates that fabrics were developed during and/or following crystallization of euhedral feldspars.…”

Section: Discussionmentioning

confidence: 99%

“…Schaen et al (, ) reveal a temporal, compositional, and textural relationship between the three domains of the Huemul pluton, indicating that rocks of the high‐silica granite are equivalent to rhyolitic melt that was extracted from a parental magma similar in composition to the granite . This melt segregation process left behind coeval residual silicic cumulates of the quartz monzonite domain with distinct textures and trace element enrichments.…”

Section: Huemul Domainsmentioning

confidence: 99%

“…Schaen et al (, ) document extraction of rhyolitic melt from the shallow (<7 km) Huemul pluton in the Chilean Andes. The Huemul pluton was syntectonically emplaced during contractional deformation of the arc and preserves magmatic fabrics developed while in a partially molten (“mushy”) state.…”

Section: Introductionmentioning

confidence: 99%

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Interpreting Granitic Fabrics in Terms of Rhyolitic Melt Segregation, Accumulation, and Escape Via Tectonic Filter Pressing in the Huemul Pluton, Chile

et al. 2018

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The physical process of rhyolite segregation from crystal mushes remains elusive as microstructural evidence of conventional segregation mechanisms is not available. This study provides direct fabric evidence for deformation‐assisted segregation of eruptible rhyolite in the Chilean Andean arc. The shallow (<7 km), 6.4–6.2 Ma Huemul pluton comprises domains of quartz monzonite, granite, and high‐silica granite. Compositional modeling shows that rhyolitic melt (high‐silica granite) was extracted from a granitic parent, leaving behind silicic cumulates (quartz monzonite). To understand mechanisms of rhyolite segregation, we investigate magmatic fabrics in the pluton. Anisotropy of Magnetic Susceptibility analyses reveal oblate magnetic fabrics and NNW‐striking, subvertical magnetic foliations throughout Huemul. Within the high‐silica granite, magnetic lineations are subvertical and parallel to elongate miarolitic cavities. Magnetic lineations in the quartz monzonite plunge moderately to the NNW, away from the high‐silica granite. In the quartz monzonite, the Shape‐Preferred Orientation of early feldspars is parallel to the magnetic lineation and developed while suspended in melt. Estimations of early feldspar clustering and crystallinity yield ~38% of interstitial volume loss in the quartz monzonite and no volume loss in the granite. These fabric data suggest ENE tectonic shortening coeval with rhyolite extraction. We explain these observations with a model of tectonic filter pressing in which shortening is accommodated by interstitial melt flow at slow (10−5 km3/yr) rates, segregating moderate volumes of rhyolite in Myr time scales. These interactions link plutonism, tectonic deformation, and upward mobility of eruptible rhyolite in tectonically active margins.

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Section: Discussionsupporting

confidence: 91%

Section: Huemul Domainssupporting

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Section: Huemul Domainsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Interpreting Granitic Fabrics in Terms of Rhyolitic Melt Segregation, Accumulation, and Escape Via Tectonic Filter Pressing in the Huemul Pluton, Chile

et al. 2018

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The origin of microgranular enclaves in the Early Cretaceous Shuangjianzishan granites in southern Great Hinggan Range, NE China

Dai

Gao

et al. 2022

Geological Journal

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The microgranular enclaves (MEs) and their host granitoids contain vital information on the genesis and evolution of the magma, especially for those which have close relationship with mineralization, yet remains a hot debate on their origin. Here, we investigate the MEs and their host granitoids in the Shuangjianzishan (SJZ) deposits, southern Great Hinggan Range, NE China, using ziron U-Pb dating and Hf isotopes, along with a systematic analysis of whole-rock geochemical and Sr-Nd isotopic compositions. The SJZ MEs mainly consist of monzonites and quartz monzonites, and the SJZ granitoids comprise a suite of fine-grained syenogranites and coarse-grained monzogranites. The zircon U-Pb dating results suggest that the SJZ granitoids and the SJZ MEs were emplaced at approximately 143-141 Ma. Geochemical features and isotopic compositions of the SJZ granitoids indicate that they are mainly generated by partial melting of juvenile lower-crustal basaltic rocks. The fine-grained syenogranites and the coarsegrained monzogranites have a gradual contact relationship, similar crystallization age, Sr-, Nd-, and Hf-isotopic compositions, suggesting that they were derived from a similar silicic magma reservoir. According to the geochemical compositions and petrographic characteristics (aggregates of coarse-grained euhedral plagioclase crystals) of the SJZ granitoids, we infer that the monzogranites (SiO 2 = 69.24-74.95 wt%) are regarded as the residual cumulate and the fine-grained syenogranites (SiO 2 = 74.83-77.97 wt%) are high silica melts segregated from a crystal mush. The SJZ MEs are characterised by low SiO 2 (50.03-64.20 wt%) and MgO (1.08-2.63 wt%) contents, high P 2 O 5 contents and contain acicular apatite, which are consistent with the products of intermediate magma.Combining with the MEs have comparable crystallization age, mineral assemblage, whole-rock Sr-Nd and zircon Hf-isotopic compositions with their host granitoids, implying the MEs were autoliths related to their host monzogranites. Collectively, we infer that the SJZ MEs were generated by the rapid cooling and crystallization of the hot ascending intermediate magmas contacted with the cooler wall rocks, then those subsolid fine-grained crystal-rich margins were fragmented and injected into the progressive evolved mush chamber, leading to the extraction and upward percolation of high silicic melts from the compacting crystal-rich mush in the shallow crust.

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The diversity and origin of granites

Bucholz

2024

Reference Module in Earth Systems and Environmental Sciences

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Textural and Mineralogical Record of Low Pressure Melt Extraction and Silicic Cumulate Formation in the late Miocene Risco Bayo-Huemul Plutonic Complex, Southern Andes

Cited by 16 publications

References 113 publications

Interpreting Granitic Fabrics in Terms of Rhyolitic Melt Segregation, Accumulation, and Escape Via Tectonic Filter Pressing in the Huemul Pluton, Chile

Interpreting Granitic Fabrics in Terms of Rhyolitic Melt Segregation, Accumulation, and Escape Via Tectonic Filter Pressing in the Huemul Pluton, Chile

The origin of microgranular enclaves in the Early Cretaceous Shuangjianzishan granites in southern Great Hinggan Range, NE China

The diversity and origin of granites

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