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The long-term (> 1 Ga) thermal histories of cratons are enigmatic, with geologic data providing only limited snapshots of their evolution. We use zircon (U-Th)/He (zircon He) thermochronology and age-composition correlations to understand the Proterozoic-Phanerozoic thermal history of Archean Wyoming province rocks exposed in the northern Laramide ranges of western North America. Zircon He ages from the Wind River Range (54 dates) and Bighorn Mountains (32 dates) show negative correlations with effective uranium (eU), a proxy for radiation damage. Zircon dates from the Bighorns are between 960 Ma (low-eU) and 20 Ma (high-eU) whereas samples from the Wind Rivers are between 582 Ma (low-eU) and 33 Ma (high-eU). We applied forward modeling using the zircon radiation damage and annealing model ZrDAAM to understand this highly variable dataset. A long-term t-T path that is consistent with the available geologic constraints successfully reproduced age-eU correlations. The best fit to the Wind Rivers data involves two phases of rapid cooling at 1800-1600 Ma and 900-700 Ma followed by slower cooling until 525 Ma. During the Phanerozoic, these samples were heated to maximum temperatures between 160-125°C prior to Laramide cooling to 50ºC between 60-40 Ma. Data from the Bighorn Mountains were successfully reproduced with a similar thermal history involving cooler Phanerozoic temperatures of ~115 °C and earlier Laramide cooling between 85-60 Ma. Our results indicate that age-eU correlations in zircon He datasets can be applied to extract long-term thermal histories that extend beyond the most recent cooling event. In addition, our results constrain the timing, magnitude and rates of cooling experienced by Archean Wyoming Province rocks between recognized deformation events, including the >1 Ga period represented by the regionally-extensive Great Unconformity. 1. Introduction Basement rocks of the Laramide ranges of northwestern Wyoming experienced a protracted thermal history involving multiple burial and exhumation episodes since their formation during the Archean. Geologic and geochronologic data indicate that prior to *Manuscript Clean (track changes accepted) Click here to view linked References their most recent exhumation in the Cenozoic and burial by several kilometers of sediment in the Paleozoic and Mesozoic, these rocks were affected by multiple Proterozoic tectonic events such as supercontinent assembly and rifting (e.g., Chamberlain et al. 2003; Marshak et al., 2000). However, specific constraints on the time-Temperature (t-T) history of the region remain enigmatic. Understanding the early Proterozoic-Mesozoic thermal history enables an integrated long-term history that could reveal previously undocumented events, including thermal maturation, cratonal stability, and orogenesis. Apatite fission track (AFT) and (U-Th)/He (apatite He) thermochronology has previously been used to resolve the thermal histories of cratons, typically over 10 8-year time scales (e.g.,

Previous constraints on the timing and rate of exhumation of the footwall of the South Tibetan detachment system (STDS) north of Mount Everest suggest rapid Miocene cooling from 7008C to 1208C between 14-17 Ma. However, 25 new single grain zircon He ages from leucogranites intruding Greater Himalayan Sequence rocks in the footwall of the STDS are between 9.9 and 15 Ma, with weighted mean ages between 10 and 12 Ma. Zircon grains exhibit a positive correlation between age and effective uranium (eU). Laser ablation zircon U-Pb geochronology, detailed SEM observations, and laser ablation depthprofiling of these zircons reveal low-eU 0.5-2.5 Ga inherited cores overgrown by high-eU 17-22 Ma rims. This intragranular zonation produces ages as much as 32% too young when a standard alpha-ejection correction assuming uniform eU distribution is applied. Modeling of the effects of varying rim thickness and rim eU concentration on the bulk grain eU and alpha-ejection correction suggests that zonation also exerts the primary control on the form of the age-eU correlation observed. Application of grain-specific zonationdependent age corrections to our data yields zircon He ages between 14 and 17 Ma, in agreement with AFT and 40 Ar/ 39 Ar ages. Growth of magmatic rims followed by cooling to < 1208C within 1-6 million years supports rapid tectonic exhumation associated with slip along the STDS in the Miocene. This study highlights the importance of characterizing parent nuclide zonation in zircon He studies which seek to understand the timing of exhumation along exhumed crustal blocks.

The tectonic and topographic history of the Himalaya-Tibet orogenic system remains controversial, with several competing models that predict different exhumation histories. Here, we present new low-temperature thermochronological data from the Mount Everest region, which, combined with thermal-kinematic landscape evolution modeling, indicate asymmetric exhumation of Mount Everest consistent with a scenario in which the southern edge of the Tibetan Plateau was located >100 km farther south during the mid-Miocene. Northward plateau retreat was caused by erosional incision during the Pliocene. Our results suggest that the South Tibetan Detachment was a localized structure and that no coupling between precipitation and erosion is required for Miocene exhumation of Greater Himalayan Sequence rocks on Mount Everest.