Zircon Dates Long-Lived Plume Dynamics in Oceanic Islands
In this contribution we report the first systematic study of zircon U-Pb geochronology and δ 18O-εHf(t) isotope geochemistry from 10 islands of the hot-spot related Galapagos Archipelago. The data extracted from the zircons allow them to be grouped into three types: (a) young zircons (0–∼4 Ma) with εHf(t) (∼5–13) and δ 18O (∼4–7) isotopic mantle signature with crystallization ages dating the islands, (b) zircons with εHf(t) (∼5–13) and δ 18O (∼5–7) isotopic mantle signature (∼4–164 Ma) which are interpreted to date the time of plume activity below the islands (∼164 Ma is the minimum time of impingement of the plume below the lithosphere), and (c) very old zircons (∼213–3,000 Ma) with mostly…
Detrital-zircon geochronology and provenance of the El Oro Metamorphic Complex, Ecuador: Geodynamic implications for the evolution of the western Gondwana margin
Abstract The El Oro Metamorphic Complex (EOMC) in SW Ecuador has been the subject of debate for several decades. While previous studies have focused on the metamorphic and deformation history of the complex to determine its geodynamic evolution, the pre-metamorphic history and its association to units in the north-central Andes remains poorly understood. Here we present a U-Pb detrital zircon provenance study to provide insights into the depositional history and the geodynamic setting of the EOMC. Our results imply that the southern portion of the EOMC (the Tahuin division) is composed of an older Palaeozoic (pre-Famatinian) sequence in the south (El Tigre unit; c. 525-510 Ma), and younger …
The Colombian geochronological database (CGD)
Geochronological databases are powerful tools for characterizing the crustal evolution and the age spectra of a region and allow comparison with other areas at a regional scale. In this contributio...
From intra-oceanic subduction to arc accretion and arc-continent collision: Insights from the structural evolution of the Río San Juan metamorphic complex, northern Hispaniola
The Río San Juan metamorphic complex exposes a segment of a high-pressure subduction-accretionary complex built during Caribbean island arc-North America continental margin convergence. It is composed of accreted arc- and oceanic-derived metaigneous rocks, serpentinized peridotites and minor metasediments forming a structural pile. Combined detailed mapping, structural and metamorphic analysis, and geochronology show that the deformation can be divided into five main events (D1eD5). An early subduction-related D1 deformation and M1 metamorphism produced greenschist (mafic rocks of the Gaspar Hernández peridotite-tectonite), blueschist and eclogite (metamafic blocks in the Jagua Clara mélang…
Recycling in the subduction factory: Archaean to Permian zircons in the oceanic Cretaceous Caribbean island-arc (Hispaniola)
Abstract Little mineralogical evidence is left of the recycling of continental and oceanic crust into the mantle at subduction zones. Zircon, because of its exceptional robustness, is probably the only surviving phase and the best mineral tracer of this global-scale process. This article combines new in-situ U-Pb dating and O and Hf isotope analyses on Cretaceous (co-magmatic) and pre-Cretaceous (inherited) zircons separated from Albian-Aptian arc-related igneous rocks from the Dominican Republic. The O and Hf systematics of Cretaceous zircons reflect derivation from predominantly juvenile sources and variable mixing with evolved melts, as expected for an oceanic island-arc. Inherited zirco…