Fault Slip and Exhumation History of the Willard Thrust Sheet, Sevier Fold‐Thrust Belt, Utah: Relations to Wedge Propagation, Hinterland Uplift, and Foreland Basin Sedimentation

Zircon (U‐Th)/He (ZHe) and zircon fission track thermochronometric data for 47 samples spanning the areally extensive Willard thrust sheet within the western part of the Sevier fold‐thrust belt record enhanced cooling and exhumation during major thrust slip spanning approximately 125–90 Ma. ZHe and zircon fission track age‐paleodepth patterns along structural transects and age‐distance relations along stratigraphic‐parallel traverses, combined with thermo‐kinematic modeling, constrain the fault slip history, with estimated slip rates of ~1 km/Myr from 125 to 105 Ma, increasing to ~3 km/Myr from 105 to 92 Ma, and then decreasing as major slip was transferred onto eastern thrusts. Exhumation was concentrated during motion up thrust ramps with estimated erosion rates of ~0.1 to 0.3 km/Myr. Local cooling ages of approximately 160–150 Ma may record a period of regional erosion, or alternatively an early phase of limited... (see full abstract in article)

Insights from low‐temperature thermochronometry into transpressional deformation and crustal exhumation along the San Andreas fault in the western Transverse Ranges, California

The San Emigdio Mountains are an example of an archetypical, transpressional structural system, bounded to the south by the San Andreas strike‐slip fault, and to the north by the active Wheeler Ridge thrust. Apatite (U‐Th)/He and apatite and zircon fission track ages were obtained along transects across the range and from wells in and to the north of the range. Apatite (U‐Th)/He ages are 4–6 Ma adjacent to the San Andreas fault, and both (U‐Th)/He and fission track ages grow older with distance to the north from the San Andreas. The young ages north of the San Andreas fault contrast with early Miocene (U‐Th)/He ages from Mount Pinos on the south side of the fault. Restoration of sample paleodepths in the San Emigdio Mountains using a regional unconformity at the base of the Eocene Tejon Formation indicates that the San Emigdio Mountains represent a crustal fragment that has been exhumed more than 5 km along the San Andreas fault since late Miocene time. Marked differences in the timing and rate of exhumation between the northern and southern sides of the San Andreas fault are difficult to reconcile with existing structural models of the western Transverse Ranges as a thin‐skinned thrust system. Instead, these results suggest that rheologic heterogeneities may play a role in localizing deformation along the Big Bend of the San Andreas fault as the San Emigdio Mountains are compressed between the crystalline basement of Mount Pinos and oceanic crust that underlies the southern San Joaquin Valley. Key Points There is Pliocene exhumation of the western Transverse Ranges Localization of deformation may be controlled by lithospheric strength Strain is partitioned between the San Andreas and regional thrustsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102707/1/tect20096.pd

Salinity Contributions from Geothermal Waters to the Rio Grande and Shallow Aquifer System in the Transboundary Mesilla (United States)/Conejos-Médanos (Mexico) Basin

Freshwater scarcity has raised concerns about the long-term availability of the water supplies within the transboundary Mesilla (United States)/Conejos-Médanos (Mexico) Basin in Texas, New Mexico, and Chihuahua. Analysis of legacy temperature data and groundwater flux estimates indicates that the region’s known geothermal systems may contribute more than 45,000 tons of dissolved solids per year to the shallow aquifer system, with around 8500 tons of dissolved solids being delivered from localized groundwater upflow zones within those geothermal systems. If this salinity flux is steady and eventually flows into the Rio Grande, it could account for 22% of the typical average annual cumulative Rio Grande salinity that leaves the basin each year—this salinity proportion could be much greater in times of low streamflow. Regional water level mapping indicates upwelling brackish waters flow towards the Rio Grande and the southern part of the Mesilla portion of the basin with some water intercepted by wells in Las Cruces and northern Chihuahua. Upwelling waters ascend from depths greater than 1 km with focused flow along fault zones, uplifted bedrock, and/or fractured igneous intrusions. Overall, this work demonstrates the utility of using heat as a groundwater tracer to identify salinity sources and further informs stakeholders on the presence of several brackish upflow zones that could notably degrade the quality of international water supplies in this developed drought-stricken region

Synchronous opening of the Rio Grande rift along its entire length at 25–10 Ma supported by apatite (U-Th)/He and fission-track thermochronology, and evaluation of possible driving mechanisms

152 new apatite (U-Th)/He (AHe) dates are presented from 34 sample locations along the flanks of the Rio Grande rift in New Mexico and Colorado. These data are combined with apatite fission-track (AFT) analyses of the same rocks and modeled together to create well constrained cooling histories for Rio Grande rift flank uplifts. The data indicate rapid cooling from ~28 Ma to Recent in the Sawatch Range and the Sangre de Cristo Mountains, ~21 to 5 Ma in the Albuquerque basin, and ~17 to 8 Ma in the southern Rio Grande rift in southern New Mexico. Rapid cooling of rift flanks followed the Oligocene ignimbrite flare-up and the northern section of the Rio Grande rift in Colorado exhibits semi-continuous cooling since the Oligocene. Overall, however, rift flank cooling along the length of the rift was out of phase with high volume magmatism and hence is inferred to have been driven mainly by exhumation due to faulting. Although each location preserves a unique cooling history, when combined with existing AHe data from the Gore Range in northern Colorado and the Sandia Mountains in New Mexico together these data indicate ~ synchronous extension and rift flank uplift along \u3e850 km of the length of the Rio Grande rift from ~20-10 Ma. These time-space constraints provide an important new dataset to develop geodynamic models for initiation and evolution of continental rifting. Models involving northward unzipping and Colorado Plateau rotation are not favored as primary mechanisms driving extension. Instead, a geodynamic model is proposed that involves upper mantle dynamics during multi-stage foundering and rollback of a segment of the Farallon plate near the Laramide hinge region that extended between the Wyoming and SE New Mexico high velocity mantle domains. First stage delamination accompanied and followed ~40-20 Ma volcanism in the San Juan and Mogollon-Datil ignimbrite centers. A second stage involved a ~30-20 Ma detachment of the remaining part of the Farallon slab. This produced renewed uplift of the Alvarado Ridge topographic high, enhanced surface uplift of rift flanks, developed a central graben with increased fault- related high strain rates, and resulted in maximum sediment accumulation in the Rio Grande rift. Our geodynamic model thus involves Oligocene removal of parts of the Farallon slab beneath the ignimbrite centers followed by a major Oligocene-Miocene slab break that instigated the discrete N-S Rio Grande rift, continuing upper mantle convection, and differential uplift of the southern Rocky Mountain - Rio Grande rift region

Combination of Ipilimumab and Adoptive Cell Therapy with Tumor-Infiltrating Lymphocytes for Patients with Metastatic Melanoma

PurposeAdoptive cell therapy (ACT) using tumor-infiltrating lymphocytes (TIL) for metastatic melanoma can be highly effective, but attrition due to progression before TIL administration (32% in prior institutional experience) remains a limitation. We hypothesized that combining ACT with cytotoxic T lymphocyte-associated antigen 4 blockade would decrease attrition and allow more patients to receive TIL.Experimental designThirteen patients with metastatic melanoma were enrolled. Patients received four doses of ipilimumab (3 mg/kg) beginning 2 weeks prior to tumor resection for TIL generation, then 1 week after resection, and 2 and 5 weeks after preconditioning chemotherapy and TIL infusion followed by interleukin-2. The primary endpoint was safety and feasibility. Secondary endpoints included of clinical response at 12 weeks and at 1 year after TIL transfer, progression free survival (PFS), and overall survival (OS).ResultsAll patients received at least two doses of ipilimumab, and 12 of the 13 (92%) received TIL. A median of 6.5 × 1010 (2.3 × 1010 to 1.0 × 1011) TIL were infused. At 12 weeks following infusion, there were five patients who experienced objective response (38.5%), four of whom continued in objective response at 1 year and one of which became a complete response at 52 months. Median progression-free survival was 7.3 months (95% CI 6.1–29.9 months). Grade ≥ 3 immune-related adverse events included hypothyroidism (3), hepatitis (2), uveitis (1), and colitis (1).ConclusionIpilimumab plus ACT for metastatic melanoma is feasible, well tolerated, and associated with a low rate of attrition due to progression during cell expansion. This combination approach serves as a model for future efforts to improve the efficacy of ACT