Intellectual Merit: This research will constrain the timescales of crustal growth and maturation in the Oman ophiolite, part of the Cretaceous oceanic lithosphere that was thrust onto the continent as a result of plate tectonic processes. Uranium-lead zircon geochronology will be used to determine the crystallization ages of the extensive gabbro and lesser plagiogranite bodies that compose the intrusive crust of the ophiolite to better than 0.05 0.1%, corresponding to absolute age errors of 50,000 90,000 years for the samples to be studied. Closely spaced samples will be collected during field work in Oman on three dimensional exposures of the ophiolite. Samples will be examined for zircons and zircons will be separated from the matrix and chemically abraded to remove alteration. Thermal ionization mass spectrometry will be used to determine high precision uranium and lead isotopic compositions which can be used to determine the age of the zircons. Goals will be to use high precision geochronology to resolve variations in intrusive magmatism in time and space during the formation of the oceanic lithosphere. The work will provide new insights into the role of intrusive off-axis magmatism at mid-ocean ridges.
Broader Impacts: Broader impacts of the work center on support of an early career scientist and inter-institutional collaboration. Work will also support the repositioning of the radiogenic isotope laboratory at MIT to allow it to investigate the origin and evolution of oceanic lithosphere as part of the long-term goals of the EARTHTIME initiative, an international effort to intercalibrate radiogenic dating techniques and use high-precision geochronology for understanding earth processes.
