Trace element and isotopic zoning of garnetite veins in amphibolitized eclogite, Franciscan Complex, California, USA

Cruz‐Uribe, Alicia M.; Page, F. Zeb; Lozier, Emilie; Feineman, M. D.; Zack, Thomas; Mertz‐Kraus, Regina; Jacob, Dorrit E.; Kitajima, Kouki

doi:10.1007/s00410-021-01795-4

Cited by 7 publications

(4 citation statements)

References 75 publications

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“…All samples described as eclogite in Table 1 (dominantly garnet and omphacite from Junction School, Ward Creek and Jenner sample 13J‐01; Figure 6a,c–f) have similar REE patterns with a maximum around Dy and variably flat to negatively‐sloped HREE. Although a changing slope in HREE (e.g., Figure 6a) is sometimes correlated with core‐rim zonation in garnet as the growth of that mineral depletes the rock's available reservoir of those elements (e.g., Cruz‐Uribe et al, 2021; Konrad‐Schmolke et al, 2008, 2022), the variability in these samples are found among grains rather than within them. These titanites formed during a blueschist facies overprinting of eclogite, which included chlorite and phengite replacement of garnet rims (e.g., Krogh et al, 1994; Oh et al, 1991; Page et al, 2007; Sorensen et al, 1997; Tsujimori et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

“…The record of fluids preserved in exhumed high‐pressure metamorphic rocks is providing new and important information in the study of fluid‐mediated mass transfer from the subducting slab to the sub‐arc mantle (e.g., Bebout & Penniston‐Dorland, 2016). One of a variety of tools that has been applied to this problem is petrographically‐guided in situ analysis of oxygen isotopes in garnet (e.g., Bovay et al, 2021; Cruz‐Uribe et al, 2021; Errico et al, 2013; Martin et al, 2014; Russell et al, 2013; Vho et al, 2020) and garnet and zircon (Page et al, 2014, 2019; Rubatto & Angiboust, 2015). This approach has been used to tie fluid infiltration events, where external fluids have modified a rock's oxygen isotope ratio to pressure, temperature, and time histories preserved in garnet and zircon.…”

Section: Introductionmentioning

confidence: 99%

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A rutile and titanite record of subduction fluids: Integrated oxygen isotope and trace element analyses in Franciscan high‐pressure rocks

Page

Storey

Eimf³

2023

Journal Metamorphic Geology

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In situ oxygen analysis of garnet in eclogite and related rocks is increasingly being used to probe the composition of subduction fluids. However, in many cases, these samples contain textural signs of both fluid flow and retrograde metamorphism, some of which may take place outside the garnet stability field. In order to test the connection between polymetamorphism and fluid infiltration, rutile rimmed by titanite from high‐grade tectonic blocks of the Franciscan Formation (California, USA) was analysed for oxygen isotope ratios and trace element concentrations. Zirconium concentrations in rutile yield temperatures of ~600°C for eclogite and hornblende eclogite from three well‐studied localities (Junction School, Tiburon and Ward Creek). Rutile trace element concentrations are generally low and consistent with a mafic protolith. Titanite surrounding rutile has inherited much of its trace element content from rutile, and Zr‐in‐titanite temperatures are spuriously high. Titanite in rutile‐free samples (blueschist and eclogite from Jenner beach) have similar compositions suggesting that they were formed at the expense of rutile as well. Oxygen isotope ratios from rutile and titanite in the same sample are fortuitously similar, indicating disequilibrium between these minerals, which formed at different times and temperatures but in equilibrium with the same oxygen reservoir. Rutile in blocks with garnets zoned in oxygen isotopes are generally in equilibrium with the rims rather than the cores. Slow oxygen diffusion in rutile and the low temperatures of formation require that rutile recrystallized after fluid interaction and before blueschist facies metamorphism. External fluid interaction of Franciscan eclogites took place near the peak of metamorphism.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A rutile and titanite record of subduction fluids: Integrated oxygen isotope and trace element analyses in Franciscan high‐pressure rocks

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Storey

Eimf³

2023

Journal Metamorphic Geology

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“…Trace element maps of a characteristic biotite grain in sample Ra‐D72 were acquired by LA‐ICP‐MS at the University of Maine using the methods described in Cruz‐Uribe et al . (2021) and Walters et al . (2022).…”

Section: Methodsmentioning

confidence: 96%

Single Spot Rb‐Sr Isochron Dating of Biotite by LA‐MC‐ICP‐MS/MS

Cruz‐Uribe

Craig

Garber

et al. 2023

Geostandard Geoanalytic Res

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Laser ablation tandem mass spectrometry is a burgeoning field for in situ Rb‐Sr geochronology. Here, we determined simultaneous isotope ratios of 87Sr/86Sr and 87Rb/86Sr in metamorphic biotite from western Maine, using an ESL™ imageGEO™193 excimer laser ablation system coupled to a Thermo Scientific™ Neoma™ MC‐ICP‐MS/MS. Measurements were made on Faraday cups with Rb+ at mass 87; Sr isotopes were reacted with SF6 gas and measured as SrF+ at masses 103–107. Twenty‐two laser spots in biotite from a single sample yield a "traditional" Rb‐Sr isochron date of 289 ± 6 Ma. Time‐resolved signals reveal significant zoning in 87Sr/86Sr and 87Rb/86Sr within single spot analyses, which were used to construct single spot isochrons. Individual laser spots contain multiple isochronous subpopulations; some spots contain up to three distinct Rb‐Sr isochrons that are decoupled from variations in Rb/Sr. Thirty‐five isochron dates were determined using this "sub‐spot" approach, with 87Sr/86Sr intercepts that systematically vary with Rb‐Sr date; two‐point isochrons were calculated for individual integrations (n = 780) based on these variable intercepts. Both methods yield age peaks at 303, 270 and 240 Ma. These data suggest that the Rb‐Sr system has the potential to record multiple heating, cooling or fluid‐alteration events spanning ~ 100 My within small domains in single biotite crystals.

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“…Fluids in subduction zones are important because of their role in transferring elements between different lithologies (Elliott, 2004; You et al., 1996) and dictating the location and extent of flux‐melting in the mantle (Grove et al., 2006; Kelley et al., 2010). In situ‐measured oxygen isotope analysis of garnet in exhumed high‐pressure/low‐temperature (HP/LT) rocks is a widely used tool to investigate evidence of fluid‐rock interactions in subduction zones (Bovay et al., 2021; Cruz‐Uribe et al., 2021; Errico et al., 2013; Martin, Rubatto, et al., 2014; Page et al., 2014). Garnet is a nominally anhydrous mineral that is commonly found in HP/LT rocks and its oxygen isotope composition is not very susceptible to intracrystalline diffusion (Coghlan, 1990; Page et al., 2010; Scicchitano et al., 2022).…”

Section: Introductionmentioning

confidence: 99%

Lawsonite and Garnet Oxygen Isotope Record of Fluid‐Rock Interaction During Subduction

Kang,

Martin,

Vitale Brovarone

et al. 2024

Geochem Geophys Geosyst

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During the subduction of an oceanic plate, fluids are released from metabasaltic crust, metasediment, and serpentinite under high‐pressure/low‐temperature conditions. Although some fluids may eventually leave the slab, some participate in metamorphic reactions within the slab during subduction and exhumation. To identify fluid sources and other controls influencing mineral composition, we report the in situ‐measured δ18O of lawsonite and garnet in blueschist‐ to eclogite‐facies rocks from 10 subduction zones that represent various field settings, including mélanges, structurally coherent terranes, and an eclogite xenolith derived from a subducted plate. Lawsonite records distinct δ18O depending on the host rock type and other rock types that were fluid sources during lawsonite growth. In general, lawsonite in metabasalt (7.6 ± 0.2–14.8 ± 1.1‰) is isotopically lighter than in metasediment (20.6 ± 1.4–24.1 ± 1.3‰) but heavier than in metagabbro (4.0 ± 0.4–7.9 ± 0.3‰). The extent of δ18O fractionation was evaluated for lawsonite–fluid and lawsonite–garnet pairs as a function of temperature (T). Results demonstrate that variations of >1.7‰ in lawsonite and >0.9‰ in garnet are not related to changing T. More likely, the relative contributions of fluids derived from isotopically heavier lithologies (e.g., sediments) versus lighter lithologies (e.g., ultramafic rocks) are the major control. Monte Carlo simulations were performed to investigate the sources of metasomatic fluids and the water/rock ratio that formed lawsonite‐bearing metasomatite. Results indicate that δ18OLws and δ18OGrt record interactions with fluids sourced from diverse lithologies (sediment, serpentinite), further supporting that δ18OLws is a useful indicator of subduction fluid‐rock interactions.

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Trace element and isotopic zoning of garnetite veins in amphibolitized eclogite, Franciscan Complex, California, USA

Cited by 7 publications

References 75 publications

A rutile and titanite record of subduction fluids: Integrated oxygen isotope and trace element analyses in Franciscan high‐pressure rocks

A rutile and titanite record of subduction fluids: Integrated oxygen isotope and trace element analyses in Franciscan high‐pressure rocks

Single Spot Rb‐Sr Isochron Dating of Biotite by LA‐MC‐ICP‐MS/MS

Lawsonite and Garnet Oxygen Isotope Record of Fluid‐Rock Interaction During Subduction

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