Paper No. 128-1
Presentation Time: 1:40 PM
NOT ALL S-TYPE GRANITES ARE CREATED EQUAL
SPENCER, Chris1, BUCHOLZ, Claire2, ANGELO, Tiago1, HE, Shaoxiong1, OLDMAN, Charlie3, LIEBMANN, Janne4, LU, Guimei5, YIN, Jiyuan6, CAVOSIE, Aaron7, WARREN, Clare8 and ROBERTS, Nicholas9, (1)Department of Geological Sciences and Geological Engineering, Queen’s University, 36 Union Street, Kingston, ON K7L2N8, Canada, (2)Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, (3)Department of Earth and Environmental Sciences, Open University, Milton Keynes, United Kingdom, (4)School of Earth and Planetary Sciences, Curtin University, Perth, WA 6845, Australia, (5)Guangzhou Institute of Geochemistry, Guangzhou, China, (6)Chinese Academy of Geological Sciences, Beijing, China, (7)Space Science and Technology Centre, School of Earth and Planetary Science, Curtin University, Bentley, WA, 6102, Australia, (8)Department of Environment, Earth and Ecosystems, The Open University, Milton Keynes, MK7 6AA, United Kingdom, (9)Geochronology and Tracers Facility, British Geological Survey, Keyworth, Nottingham NG12 5GG, United Kingdom
Sediment-derived melts and the detrital products derived therefrom have been present in the geologic record since the Hadean Eon. While they are often smaller in volume compared to other felsic melts from arc settings, understanding the mode and volume of sediment assimilation is crucial to grasp the interplay between Earth's surface and its depths. Recent research has shown that changes in sedimentary compositions over time are mirrored in the composition of sediment-derived melts. This makes detrital mineral proxies unreliable for estimating the volume of sediment-derived melts through time.
The clastic sedimentary record is also extremely diverse in its isotopic signatures and degree of maturity. This compositional diversity is reflected in sediment-derived melts that reflect specific isotopic features of various petrotectonic settings. Sediment-derived melts are present oceanic and continental arcs as well as continental collisions. Oceanic arcs record sediment-derived melts with elevated δ18O but depleted εHf, whereas continental collisions produce melts with elevated δ18O and enriched εHf. In contrast, long-lived continental arc systems yield dramatic swings in isotopic signatures during the oscillations of retreating and advancing arc phases. Ophiolites also host sediment-derived granites intruding peridotite that carry isotopic signatures akin to biogenic sediments implying subduction and melting of deep marine sediment.
Sediment melting mechanisms vary, and specific mineral proxies can distinguish between fluid-present melting and muscovite- and biotite-dehydration melting. Identifying these mechanisms helps understand the conditions and compositional diversity of sediment-derived melts. Sediment-derived melts record plate tectonic-driven mass transfer and connect evolving surface conditions with the deep Earth. Despite being relatively low in volume, these granitoids are essential for comprehending the long-term evolution of plate tectonics and the sedimentary systems that contribute to their formation.
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