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  • 2020-2024  (2)
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  • 1
    Publikationsdatum: 2024-03-22
    Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Heat flow is estimated at eight sites drilled int the Guaymas Basin, Gulf of California, during the International Ocean Discovery Program Expedition 385. The expedition sought to understand the thermal regime of the basin and heat transfer between off‐axis sills intruding the organic‐rich sediments of the Guaymas Basin, and the basin floor. The distinct sedimentation rates, active tectonics, and magmatism make the basin interesting for scientific discoveries. Results show that sedimentation corrected heat flow values range 119–221 mW/m〈sup〉2〈/sup〉 in the basin and 257–1003 mW/m〈sup〉2〈/sup〉 at the site of a young sill intrusion, denominated Ringvent. Thermal analysis shows that heat in the Guaymas Basin is being dissipated by conduction for plate ages >0.2 Ma, whereas younger plate ages are in a state of transient cooling by both conduction and advection. Drilling sites show that Ringvent is an active sill being cooled down slowly by circulating fluids with discharge velocities of 10–200 mm/yr. Possible recharge sites are located ca. 1 km away from the sill's border. Modelling of the heat output at Ringvent indicates a sill thickness of ca. 240 m. A simple order‐of‐magnitude model predicts that relatively small amounts of magma are needed to account for the elevated heat flow in non‐volcanic, sediment‐filled rifts like the central and northern Gulf of California in which heating of the upper crust is achieved via advection by sill emplacement and hydrothermal circulation. Multiple timescales of cooling control the crustal, chemical and biological evolution of the Guaymas Basin. Here, we recognize at least four timescales: the time interval between intrusions (ca. 10〈sup〉3〈/sup〉 yr), the thermal relaxation time of sills (ca. 10〈sup〉4〈/sup〉 yr), the characteristic cooling time of the sediments (ca. 10〈sup〉5〈/sup〉 yr), and the cooling of the entire crust at geologic timescales.〈/p〉
    Beschreibung: Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California http://dx.doi.org/10.13039/501100003089
    Beschreibung: German Research Center for Geosciences
    Beschreibung: https://web.iodp.tamu.edu/LORE/
    Beschreibung: https://mlp.ldeo.columbia.edu/logdb/scientific_ocean_drilling/
    Schlagwort(e): ddc:551.1 ; Guyamas Basin ; Heat Flow ; Heat Transfer ; IODP Expedition 385
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Publikationsdatum: 2024-02-07
    Beschreibung: Highlights • Syn-rift sediments in the northern South China Sea are from the East Cathaysia block. • Rivers delivered sediments migrated from eastern to western region. • Tributaries catchment of the Pearl River started to migrate since the late Eocene. • The migration of the river catchment is related to the west-east topographic swap. • Topographic change was possibly related to the local tectonic uplift and exhumation. We examined an International Ocean Discovery Program (IODP) drilling core from Site U1501, located on the distal margin of the northern South China Sea (SCS) basin to unravel the sediment provenance evolution in the Paleogene and the evolution of river catchments during basin opening. We attempt to understand the major factors driving river development in a rift basin by utilizing provenance tools to constrain sediment transport pathways and compare these with the regional tectonics during the Paleogene in order to resolve competing models for drainage evolution and test their relationships with the evolving topography of SW China and the SE Tibetan Plateau. For this purpose, ten samples were collected from a 200-m-thick, syn-rift Eocene/pre-Eocene interval. Detrital zircon U-Pb data were collected by LA-ICP-MS to identify the sediment provenance and differentiate fluvial sources. Bulk rock geochemistry data was utilized to shed light on chemical weathering conditions and compositional maturity to further decipher sediment transportation patterns. We compare our data with adjacent IODP Site U1435 and several industrial boreholes located in the Pearl River Mouth Basin (PRMB). We applied multiple statistical tests, including K-S, Monte Carlo mixing and multidimensional scaling testing, to evaluate U-Pb age spectra similarities and to estimate endmember contributions from a variety of source areas. Our results from Site U1501 show that sediments deposited as fluvial sands during the rifting stage, were predominantly derived from the East Cathaysia block, probably from local sources. A progressive increase in older detrital zircon U-Pb ages peaks (〉200 Ma) was observed at Site U1435 and in PRMB strata, signaling a spatial shift in sediment provenance from east to west occurring between the late Eocene and the early Oligocene. This trend reflects a transition in sediment delivery from local small-catchment streams to a more regional drainage eroding the east and north of the South China Block. Westward drainage expansion is likely impacted by the uplift of the Tibetan Plateau.
    Materialart: Article , PeerReviewed
    Format: text
    Format: other
    Standort Signatur Einschränkungen Verfügbarkeit
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