Source of fluids forming distal Zn-Pb-Ag skarns: Evidence from laser ablation–inductively coupled plasma–mass spectrometry analysis of fluid inclusions from El Mochito, Honduras

Samson, Iain M.; Williams‐Jones, Anthony E.; Ault, Katherine M.; Gagnon, Joel E.; Fryer, Brian J.

doi:10.1130/g25214a.1

Cited by 74 publications

(26 citation statements)

References 18 publications

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“…The aqueous chemistry of Types 1 and 2 inclusions is compared to compositions of magmatic fluids from granite‐related ore deposits, basinal brines and fluids from distal Zn–Pb–Ag skarns hosted by siliciclastic rocks and limestones at El Mochito, Honduras (Fig. ; Samson et al ., ). The EJB aureole Types 1 and 2 fluids occupy the skarn field of the El Mochito deposit or its proximity, which is distinguished by relatively high Ca/K and K/Na ratios and Mn concentrations compared to the other two environments.…”

Section: Discussionmentioning

confidence: 97%

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Properties of fluids attending variable recrystallization of quartzite during contact metamorphism in the White‐Inyo Range, California

Nábělek

Stephenson

Morgan

et al. 2016

Journal Metamorphic Geology

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Fluid inclusions in the metamorphic aureole of the Eureka Valley-Joshua Flat-Beer Creek (EJB) pluton in the White-Inyo Range, California, reveal the compositions and origin of fluids that were present during variable recrystallization of quartzite with sedimentary grain shapes to metaquartzite with granoblastic texture. Metamorphosed sedimentary formations, including quartzites, marbles, calcsilicates and schists, became ductile and strongly attenuated in the aureole during growth of the magma chamber. The microstructures of quartzites have an unusual distribution in that within~250 m from the pluton, where temperatures exceeded 650°C, they exhibit relict sedimentary grain shapes, only small amount of grain boundary migration (GBM), and crystallographic preferred orientations (CPOs) dominated by slip. At distances >250 m, quartzites were completely recrystallized by GBM and CPOs are indicative of prism [c] slip, characteristics that are typically associated with H 2 O-assisted, high-T recrystallization. The lack of extensive GBM in the inner aureole can be attributed to rapid replacement of H 2 O by CO 2 produced by reaction of quartz grains with calcite cement that also produced interstitial wollastonite. Fluid inclusions in the inner aureole generally occur in margins of quartz grains and are either wholly aqueous (Type 1) or also contain H 2 S, CO 2 and CH 4 (Type 2). Type 2 inclusions occur only in some stratigraphic layers. In both inclusion types, NaCl and CaCl 2 , in variable proportions, dominate the solutes in the aqueous phase, whereas FeCl 2 and KCl are less abundant solutes. The solutes indicate attainment of a degree of equilibrium with carbonates and schists that are interbedded with the quartzites. Some Types 1 and 2 inclusions in the inner aureole show evidence of decrepitation due to high amounts of strain and/or heating suffered by the host rocks, which suggests that they represent pore fluids that existed in the rocks prior to contact metamorphism. In addition to Type 1 inclusions, outer aureole quartzites also contain inclusions that contain CO 2 vapour bubbles in addition to aqueous phase (Type 3). These inclusions only occur in interiors of granoblastic quartz that was produced by large amounts of GBM. The aqueous phase has identical ranges of first melting and final ice melting temperatures as Type 1 inclusions, suggesting that they have the same solute compositions. These inclusions are thought to represent the interstitial pore H 2 O that promoted recrystallization of quartz and reacted with graphite to produce CO 2 . Absence of significant amounts of CH 4 in Type 3 inclusions is attributed to elevated fO 2 that was buffered by mineral assemblages in interbedded schists. As opposed to the large amount of CO 2 that was produced by the wollastonite-forming reaction in the inner aureole to inhibit GBM, the amount of CO 2 produced in the outer aureole by reaction between H 2 O and graphite was apparently insufficient to inhibit recrystallization of quartz.

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Section: Discussionmentioning

confidence: 97%

“…The El Mochito inclusions have, however, more elevated trapping temperatures (325–425 °C), that prompted Samson et al . () to suggest that the skarn fluids were magmatic that equilibrated along the flow path with carbonates to preferentially elevate the Ca/K ratios compared to normal magmatic fluids.…”

Section: Discussionmentioning

confidence: 99%

Properties of fluids attending variable recrystallization of quartzite during contact metamorphism in the White‐Inyo Range, California

Nábělek

Stephenson

Morgan

et al. 2016

Journal Metamorphic Geology

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“…The Honduras region (Central America) is a well-known metallogenic province, which is represented by several areas of hydrothermally altered metamorphic rocks that are related to the Late Cretaceous-Early Tertiary magmatic systems extending from Guatemala to Costa Rica (e.g., Roberts and Irving, 1957;Samson et al, 2008;Sundblad et al, 1991;Williams-Jones et al, 2010). However, with the exception of gold deposits in the Rosario Mining District (San Juancito Mts.…”

Section: Introductionmentioning

confidence: 98%

Gold mineralisations in the Canan area, Lepaguare District, east-central Honduras: Fluid inclusions and geochemical constraints on gold deposition

Salvioli-Mariani

Toscani

Boschetti

et al. 2015

Journal of Geochemical Exploration

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“…Many advanced analytical techniques rely on microthermometric data for quantification of the results; for example, the determination of concentrations of trace elements in fluid inclusions using the LA-ICP-MS method requires the salinity values estimated from microthermometric data as internal standards (e.g. Samson et al 2008;Wilkinson et al 2009;Richard et al 2012).…”

Section: Introductionmentioning

confidence: 99%

“…inability for fluid inclusions to freeze or to nucleate a vapor bubble) and occurrence of phases unexpected to be present in equilibrium (Roedder 1962(Roedder , 1971(Roedder , 1984. These problems are particularly common for fluid inclusions of the H 2 O-NaCl-CaCl 2 system (Davis et al 1990;Samson & Walker 2000;Bodnar 2003), which are well developed in a variety of geological environments including sedimentary basins, magmatic hydrothermal systems and metamorphic terranes (Crawford 1981;Vanko et al 1988;Chi & Savard 1997;Xu 2000;Derome et al 2005;Samson et al 2008;Stoffell et al 2008;Richard et al 2010Richard et al , 2012. H 2 O-NaCl-CaCl 2 fluid inclusions, especially those that are CaCl 2 rich, are notoriously difficult to freeze (Roedder 1984;Samson & Walker 2000;Chi et al 2014), and apparently frozen inclusions commonly show various melting-like behaviors in the warming process before reaching the eutectic temperature of À52°C (Davis et al 1990).…”

Section: Introductionmentioning

confidence: 99%

Freezing and melting behaviors of H₂O‐NaCl‐CaCl₂ solutions in fused silica capillaries and glass‐sandwiched films: implications for fluid inclusion studies

2016

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Fluid inclusions of the H2O‐NaCl‐CaCl2 system are notorious for their metastable behavior during cooling and heating processes, which can render microthermometric measurement impossible or difficult and interpretation of the results ambiguous. This study addresses these problems through detailed microscopic examination of synthetic solutions during cooling and warming runs, development of methods to enhance nucleation of hydrates, and comparison of microthermometric results with different degrees of metastability with values predicted for stable conditions. Synthetic H2O‐NaCl‐CaCl2 solutions with different NaCl/(NaCl + CaCl2) ratios were prepared and loaded in fused silica capillaries and glass‐sandwiched films for microthermometric studies; pure solutions were used with the capillaries to simulate fluid inclusions, whereas alumina powder was added in the solutions to facilitate ice and hydrate crystallization in the sandwiched samples. The phase changes observed and the microthermometric data obtained in this study have led to the following conclusions that have important implications for fluid inclusion studies: (i) most H2O‐NaCl‐CaCl2 inclusions that appear to be completely frozen in the first cooling run to −185°C actually contain large amounts of residual solution, as also reported in some previous studies; (ii) inability of H2O‐NaCl‐CaCl2 inclusions to freeze completely may be related to their composition (low NaCl/(NaCl + CaCl2) ratios) and lack of solid particles; (iii) crystallization of hydrates, which is important for cryogenic Raman spectroscopic studies of fluid inclusion composition, can be greatly enhanced by finding an optimum combination of cooling and warming rates and temperatures; and (iv) even if an inclusion is not completely frozen, the melting temperatures of hydrohalite and ice are still valid for estimating the fluid composition.

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Source of fluids forming distal Zn-Pb-Ag skarns: Evidence from laser ablation–inductively coupled plasma–mass spectrometry analysis of fluid inclusions from El Mochito, Honduras

Cited by 74 publications

References 18 publications

Properties of fluids attending variable recrystallization of quartzite during contact metamorphism in the White‐Inyo Range, California

Properties of fluids attending variable recrystallization of quartzite during contact metamorphism in the White‐Inyo Range, California

Gold mineralisations in the Canan area, Lepaguare District, east-central Honduras: Fluid inclusions and geochemical constraints on gold deposition

Freezing and melting behaviors of H₂O‐NaCl‐CaCl₂ solutions in fused silica capillaries and glass‐sandwiched films: implications for fluid inclusion studies

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Source of fluids forming distal Zn-Pb-Ag skarns: Evidence from laser ablation–inductively coupled plasma–mass spectrometry analysis of fluid inclusions from El Mochito, Honduras

Cited by 74 publications

References 18 publications

Properties of fluids attending variable recrystallization of quartzite during contact metamorphism in the White‐Inyo Range, California

Properties of fluids attending variable recrystallization of quartzite during contact metamorphism in the White‐Inyo Range, California

Gold mineralisations in the Canan area, Lepaguare District, east-central Honduras: Fluid inclusions and geochemical constraints on gold deposition

Freezing and melting behaviors of H2O‐NaCl‐CaCl2 solutions in fused silica capillaries and glass‐sandwiched films: implications for fluid inclusion studies

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Freezing and melting behaviors of H₂O‐NaCl‐CaCl₂ solutions in fused silica capillaries and glass‐sandwiched films: implications for fluid inclusion studies