NC State
MEAS Undergraduate Updates
Hi everyone.  Our next MEAS Dept. Seminar is this Monday, Oct. 3, 330PM, in 1216 Jordan Addition   The seminar will be given by Dr. Kennet Flores of UNC-Chapel Hill and will also be available by Zoom.
Seminar title – Record of fluid-rock interaction in a long-lived subduction interface
Bio – Dr. Kennet Flores is an Assistant Professor at the University of North Carolina at Chapel Hill.  Before joining the faculty at the University of North Carolina (UNC) in 2021, he was a postdoctoral fellow at the American Museum of Natural History in New York. He holds a DEA and Ph.D. from the University of Lausanne, Switzerland, and a B.S. degree from the Universidad de Costa Rica. Dr. Flores has published more than 30 peer-reviewed papers.
Abstract – Subduction zones are the primary location for element recycling from the Earth’s surface into the mantle. Subducting plates release fluids that play a crucial role in generating intraslab earthquakes, serpentinization, and flux melting of the mantle wedge to yield arc volcanism. Exhumed remnants of slab-mantle interfaces represent our only record, albeit incomplete, of the history of fluid transfer and fluid-rock interaction. Highly-retrogressed eclogites within the North Motagua Mélange (central Guatemala) preserve extensive chemical alterations that record rehydration reactions at the plate interface at depths of ~80-30 km. Our new results suggest that these rocks reached peak burial at eclogite-facies conditions (550-600°C, 2.0-2.5 GPa) and were sliced off the slab at 114-113 Ma. These rocks also preserve two fluid-related retrogression events: (i) An initial rehydration event at blueschist-facies conditions (500-550°C, 1.5-2.0 GPa) at 100-89 Ma and characterized by significant whole-rock enrichment in fluid-mobile elements (e.g., K, Ba, Pb). (ii) At 82-73 Ma, a second retrogression stage occurred at Ep-amphibolite-facies conditions (450-500°C, 0.8-1.0 GPa) and was associated with the infiltration of Ca-Na-rich fluids. These two phases occurred during ~40 Myrs of storage-decompression within the subduction interface before a final exhumation stage. Throughout this residence time, slab-derived fluids infiltrated the subduction interface, triggering mantle serpentinization, fluid-related vein crystallization (e.g., jadeitites), and rehydration of ascending eclogites. Our results suggest that retrograde eclogites and fluid-related rocks in serpentinite mélanges (frequently ignored due to their complexity) contain critical clues to reconstruct the record and timing of fluid migrations and fluid-rock interactions in subduction zones.