Geochemical constraints on the temperature and timing of carbonate formation and lithification in the Nankai Trough, NanTroSEIZE transect

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doi: 10.1016/j.gca.2016.10.013
Author(s): Sample, James C.; Torres, Marta E.; Fisher, Andrew; Hong, Wei-Li; Destrigneville, Christine; Defliese, William F.; Tripati, Aradhna E.
Author Affiliation(s): Primary:
Northern Arizona University, School of Earth Sciences and Environmental Sustainability, Flagstaff, AZ, United States
Oregon State University, United States
Université de Toulouse, France
University of California at Los Angeles, United States
Volume Title: Geochimica et Cosmochimica Acta
Source: Geochimica et Cosmochimica Acta, Vol.198, p.92-114. Publisher: Elsevier, New York, NY, International. ISSN: 0016-7037 CODEN: GCACAK
Note: In English. Includes appendices. 80 refs.; illus., incl. 2 tables, sketch map
Summary: Information about diagenetic processes and temperatures during burial of sediments entering the subduction zone is important for understanding changes in physical properties and seismic behavior during deformation. The geochemistry of authigenic carbonates from accretionary prisms can serve as proxies for conditions during carbonate cementation and resultant lithification. We report results from the Nankai accretionary prism recovered from Integrated Ocean Drilling Program (IODP) sites C0011 and C0012 and we document continued cementation of deep sediment sections prior to subduction. Elemental and isotope data provide evidence for complex mixing of different isotopic reservoirs in pore waters contributing to carbonate chemical signatures. Carbon stable isotope values exhibit a broad range (δ13CV-PDB = +0.1 ppm to -22.5 ppm) that corresponds to different stages of cement formation during burial. Carbonate formation temperatures from carbonate-clumped isotope geochemistry range from 16 °C to 63 °C at Site C0011 and 8.7 °C to 68 °C at Site C0012. The correspondence between the clumped-isotope temperatures and extrapolations of measured in situ temperatures indicate the carbonate is continuing to form at present. Calculated water isotopic compositions are in some cases enriched in 18O relative to measured interstitial waters suggesting a component of inherited seawater or input from clay-bound water. Low oxygen isotope values and the observed Ba/Ca ratios are also consistent with carbonate cementation at depth. Strontium isotopes of interstitial waters (87Sr/86Sr of 0.7059-0.7069) and carbonates (87Sr/86Sr of 0.70715-0.70891) support formation of carbonates from a mixture of strontium reservoirs including current interstitial waters and relic seawater contemporaneous with deposition. Collectively our data reflect mixed sources of dissolved inorganic carbon and cations that include authigenic phases driven by organic carbon and volcanic alteration reactions. Physical properties of input sediments continue to undergo modification by carbonate cementation at present. Due to ongoing recrystallization, temperatures from carbonate-clumped isotopes reflect the modern geothermal gradient and may serve as useful measures of geothermal gradients in other siliciclastic basins where carbonate cementation occurs. We conclude that clumped-isotope signatures in authigenic carbonates from accretionary prisms are important proxies for the timing and conditions of cementation in active margins. Our results highlight the importance of using multi-proxy approaches to elucidate the history of carbonate cementation, particularly to establish carbonate precipitation at depth and its potential impact on the physical and mechanical properties of the sediment prior to subduction.
Year of Publication: 2017
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 02 Geochemistry; 06 Petrology, Sedimentary; Alkaline earth metals; C-13/C-12; Carbon; Carbonate rocks; Carbonates; Cement; Crystal chemistry; Crystallization; EDS spectra; Electron microscopy data; Electron probe data; Geophysical methods; Geophysical surveys; Geothermal gradient; Heat flow; IODP Site C0011; IODP Site C0012; Integrated Ocean Drilling Program; Isotope ratios; Isotopes; Lithification; Metals; NanTroSEIZE; Nankai Trough; North Pacific; Northwest Pacific; O-18/O-16; Oxygen; Pacific Ocean; SEM data; Sedimentary rocks; Seismic methods; Shikoku Basin; Spectra; Sr-87/Sr-86; Stable isotopes; Strontium; Surveys; Temperature; West Pacific; X-ray diffraction data; X-ray spectra
Coordinates: N324944 N324945 E1365256 E1365254
Record ID: 2017041220
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands