Abstract The processes that result in arc magmas are critical to understanding element recycling in subduction zones, yet little is known about how these systems evolve with time. Nicaragua provides an opportunity to reconstruct the history of a volcanic arc since the Cretaceous. Here we present the stratigraphy of the Cretaceous–Eocene volcanic units in Nicaragua and their relationship to the different tectonic units where the arc developed. We discovered an evolution from an arc‐dominated by calc‐alkaline compositions in the Cretaceous–Eocene, to transitional compositions in the Oligocene–Miocene, to finally tholeiitic magmas common in the modern volcanic front. Our petrographic studies confirm that in the Cretaceous–Eocene the olivine + clinopyroxene cotectic was followed by clinopyroxene + plagioclase ± amphibole. Given the abundance of amphibole and the lack of this mineral in the modern volcanic front, the Cretaceous–Eocene Arc melts were likely more water‐rich than modern Nicaragua, suppressing the crystallization of plagioclase after olivine. We also found temporal changes in element ratios that are sensitive to variations in sediment input. The Cretaceous–Eocene Arc is characterized by a lower Ba/Th compared to the Oligocene–Miocene and modern volcanic front samples, suggesting that the sediment input was lower in Ba, possibly analogous to old deep siliceous sediment subducting in the western Pacific. Both U/Th and U/La are higher in the modern volcanics, reflecting higher U/Th in the subducting sediments following the 'Carbonate Crash'. Finally, we found that the orientation of the arc axis also changed, from northeast‐southwest in the Cretaceous–Eocene to northwest‐southeast after the Oligocene. This change probably records variations in the location of the subduction zone as this region shaped into its current geographic configuration.

Volcanic arc

Amphibole

Island arc

10.1111/iar.12346

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Citations (10)

Plume-Ridge Interaction During Large Igneous Province Formation

AGUFM (2018)

P. Madrigal Quesada Esteban Gazel Kennet E. Flores Michael Bizimis Brian R. Jicha

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Unraveling the history of complex zoned garnets from the North Motagua Mélange (Guatemala)

AGU Fall Meeting Abstracts (2016)

Mattison H. Barickman Céline Martin Kennet E. Flores George E. Harlow Guillaume Bonnet

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A melt-focusing zone in the lithospheric mantle preserved in the Santa Elena Ophiolite, Costa Rica

Lithos (2015)

Pilar Madrigal Esteban Gazel Percy Denyer Ian E.M. Smith Brian R. Jicha

10.1016/j.lithos.2015.04.015

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Citations (19)

Exhumed Serpentinites and Their Tectonic Significance in Non‐Collisional Orogens

Geochemistry Geophysics Geosystems (2024)

Damián Donoso‐Tapia Kennet E. Flores Céline Martin Esteban Gazel Jeffrey Marsh

Abstract Exhumed serpentinites are fragments of ancient oceanic lithosphere or mantle wedge that record deep fluid‐rock interactions and metasomatic processes. While common in suture zones after closure of ocean basins, in non‐collisional orogens their origin and tectonic significance are not fully understood. We study serpentinite samples from five river basins in a segment of the non‐collisional Andean orogen in Ecuador (Cordillera Real). All samples are fully serpentinized with antigorite as the main polymorph, while spinel is the only relic phase. Watershed delineation analysis and in‐situ B isotope data suggest four serpentinite sources, linked to mantle wedge (δ 11 B = ∼−10.6 to −0.03‰) and obducted ophiolite (δ 11 B = −2.51 to +5.73‰) bodies, likely associated with Triassic, Jurassic‐Early Cretaceous, and potentially Late Cretaceous‐Paleocene high‐pressure (HP)–low‐temperature metamorphic sequences. Whole‐rock trace element data and in‐situ B isotopes favor serpentinization by a crust‐derived metamorphic fluid. Thermodynamic modeling in two samples suggests serpentinization at ∼550–500°C and pressures from 2.5 to 2.2 GPa and 1.0–0.6 GPa for two localities. Both samples record a subsequent overprint at ∼1.5–0.5 GPa and 680–660°C. In the Andes, regional phases of slab rollback have been reported since the mid‐Paleozoic to Late Cretaceous. This tectonic scenario favors the extrusion of HP rocks into the forearc and the opening of back‐arc basins. Subsequent compressional phases trigger short‐lived subduction in the back‐arc that culminates with ophiolite obduction and associated metamorphic rock exhumation. Thus, we propose that serpentinites in non‐collisional orogens are sourced from extruded slivers of mantle wedge in the forearc or obducted ophiolite sequences associated with regional back‐arc basins.

Forearc

Obduction

Peridotite

Metamorphic core complex

10.1029/2023gc011072

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Origin of the Meta-Ultramafic Rocks from Massachusetts and Staten Island, New York: a Complex History

AGU Fall Meeting Abstracts (2019)

Kennet E. Flores Céline Martin George E. Harlow

Ultramafic rock

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