OLDER PROJECTS (Prior to 2017)
Exhumation of the Indus-Yarlung Suture Zone (IYSZ) Many of the rocks found along the IYSZ were deposited at or near sea level, but today sit at elevations greater than 5000 m. In addition, many of these rocks show evidence for deep burial prior to exhumation and uplift. I seek to resolve the time-temperature history of the IYSZ through the application of multiple low-temperature thermochronmeters, including Apatite and Zircon Helium dating. Check out my article in Geoscience Frontiers: Orme (2017).
Xigaze Forearc Basin, southern Tibet The Xigaze forearc basin in southern Tibet, one of the largest and best-preserved forearc basins on Earth, records upper-plate processes active prior to and following the inter-continental collision between India and Asia. However, the understanding of the timing and mechanisms of forearc development and its evolution following collision is spatially and temporally limited. Fundamental questions remain concerning how the basin formed, its paleogeography prior to collision, its subsidence history and the thermal history of the basin following the initial and ongoing continent-continent collision. Answering these questions is important to reconstructing upper plate dynamics during active subduction of oceanic and continental lithosphere. This research addresses the Early Cretaceous to Pliocene history of the Xigaze forearc, using field mapping, sedimentology, sandstone modal petrography, geohistory analysis, U-Pb detrital zircon geochronology, and low-temperature thermochronology (apatite and zircon (U-Th)/He and fission track). This work is now published in Basin Research (Orme et al. 2015) and Journal of Sedimentary Research (Orme and Laskowski, 2016)
(U-Th)/He dates of apatite grains from some environments display significantly more dispersion than predicted by known sources such as varying grain size, radiation damage, or parent-nuclide zoning. In addition, many of these apatites show secondary external phases which contain significant amounts of U-Th relative to the apatite. Our research seeks to understand the potential impact of these U-Th-bearing phases on AHe dates. This work is now published in Chemical Geology (Link: Murray et al. 2014).