Heat and mass are injected into the shallow crust when mantle fluids able to flow through ductile lower crust. Minimum 3 He/ 4 He ratios in surface from northern Basin Range Province, western North America, increase systematically low crustal values east high west, a regional trend that correlates with rates of active deformation. The highest occur where extension shear strain greatest. correspondence helium isotope transtensional deformation indicates deformation-enhanced permeability can...

Abstract Lesser Antilles arc lavas have trace element and radiogenic isotope characteristics indicative of a continent-derived contribution. It is debated vigorously whether this continental signature represents terrigenous sediment that has been subducted with the Atlantic plate added to magma sources in mantle wedge, or portions subarc crust are assimilated during ascent. Here we present Mo data for sediments offboard trench. Sequences black shales, subducting piles, highly enriched...

The timing of collision the Cocos Ridge at Middle America Trench remains one outstanding questions in tectonic evolution Central American convergent margin. New analyses geomorphology Cordillera de Talamanca, extinct volcanic arc inboard Ridge, coupled with low temperature thermochronometry data, provide insight into cooling and erosional history from late Miocene to present. We identify a low‐relief surface high elevation along northeastern flanks range, which represents relict landscape...

A precise age for the collision of Kohistan-Ladakh block with Eurasia along Shyok suture zone (SSZ) is one key to understanding accretionary history Tibet and tectonics during India-Eurasia collision. Knowing SSZ also allows be used as a piercing line calculating total offset Karakoram Fault, which effectively represents SE border Tibetan Plateau has played major role in plateau evolution. We present combined structural, geochemical, geochronologic study it exposed Nubra region India test...

Abstract The Taiwan orogenic belt is often treated as a steady, southward-propagating system with an essentially constant erosion rate of 4–6 mm/yr over the past 5 m.y. We present 4 new age-elevation transects from Central Range based on 19 and 86 previously published fission track (U-Th)/He dates completely reset detrital zircon apatite grains. curves thermal models imply slow cooling prior to ca. 2–1.5 Ma (at exhumation rates ∼0.1 mm/yr), increase in 0.5 (2–4 possibly further acceleration...

Apatite and zircon (U‐Th)/He ages from Ocoña canyon at the western margin of Central Andean plateau record rock cooling histories induced by a major phase incision. We quantify timing magnitude incision integrating previously published valley bottom with 19 new sample four wall transects. Interpretation history is complicated southwest to northeast increase in temperatures base crust due subduction volcanism. Furthermore, large leads additional three‐dimensional variations thermal field....

Structural and thermochronologic studies of the western margin central Andean Plateau show changing styles deformation through time that give insights into tectonic evolution. In southwest Peru, uplift plateau proceeded in several distinct phases. First, NW striking, NE dipping reverse faults accommodated prior to ∼14–16 Ma. Subsequent relative piedmont (between Pacific Ocean) occurred between ∼14 2.2 Ma was by SW normal subparallel monoclinal folds. The youngest phase affected region as a...

Abstract Detrital mineral thermochronology of modern sediments is a valuable tool for interrogating landscape evolution. zircon (U‐Th)/He particular interest because zircons are durable and withstand transport in glacial fluvial systems far better than, example, apatite. However, the time‐intensive nature conventional thermochronology, most previous studies this kind have relied on data few tens grains, even though wisdom holds that substantially larger number necessary robust...

Abstract Chemical differences between mid-ocean ridge basalts (MORBs) and ocean island (OIBs) provide critical evidence that the Earth’s mantle is compositionally heterogeneous. MORBs generally exhibit a relatively low narrow range of 3 He/ 4 He ratios on global scale, whereas OIBs display larger variability in both time space. The primordial origin has motivated hypotheses high are product plumes sampling chemically distinct material, but do not account for lower MORB-like OIBs, nor their...

The accurate dating of meteorite impact structures on Earth has proven to be challenging. Melt sheets are amenable high‐precision by the U‐Pb and 40 Ar/ 39 Ar methods, but many events do not produce them, or they preserved. In cases where high‐temperature shock metamorphism target materials occurred without widespread melting, these isotopic chronometers may partially reset yield dates that difficult interpret unambiguously as age impact. However, (U‐Th)/He chronometer is sensitive thermal...

The observed geomorphology and calculated thermal histories of the Bhutan Himalaya provide an excellent platform to test ideas regarding influence tectonics climate on evolution a convergent mountain range.However, little consensus has been reached late Cenozoic history Himalaya.Some researchers have argued that geologic relationships show slowing deformation rates, such range is decaying from geomorphic perspective, while others see as growing steepening.We suggest better understanding...

Abstract The Greater Caucasus (GC) Mountains within the central Arabia‐Eurasia collision zone are an archetypal example of a young collisional orogen. However, mechanisms driving rock uplift and forming topography range controversial, with recent provocative suggestions that western GC is strongly influenced by isostatic response to slab detachment, whereas eastern half has grown through shortening crustal thickening. Testing this hypothesis challenging because records exhumation rates...

We report an extensive helium isotope survey of basaltic to andesitic lavas from the Lesser Antilles island arc—an arc system with well-documented evidence crustal contamination. Given sensitivity isotopes as a tracer effects additions, our aim is evaluate relationship 3He/4He ratios other indices contamination processes such oxygen and strontium isotopes. To this end, we have carried out 53 analyses on separated minerals (olivines pyroxenes) throughout arc, which compare whole-rock...

Abstract Most successful efforts to determine the ages of impact events are based on isotope geochronology crystalline or glassy melts. Studies sites Earth show that many form without significant melt production, meaning traditional geochronologic approaches can yield unsatisfying results. We describe here an alternative approach theoretical calculations even brief thermal related reset isotopic systematics unmelted target rocks. Thermochronometers production radiogenic 4 He in accessory...