Here we review regional geological, petrological, geochemical, and geophysical data from the Central Andean plateau (comprising two distinct areas, the Altiplano and Puna) and its defunct North American sibling, the Nevadaplano, as well as to a lesser extent Tibet, to show that magmatism in the middle crust of orogenic plateaus plays an important role in the development of relief and high elevation and drives the mechanical behavior of these features. We show that in situ, mostly S-type melting is an intrinsic feature of plateaus and that these melts can reside in the crust for millions to tens of millions of years without freezing just below a critical melt fraction. Some of these in situ partial melt masses escape their source regions and erupt at the surface. The chemical evolution of volcanic masses produced by partial escape from these migmatites can be predicted by simple forward petrologic calculations. Extensive migmatite in sub-plateau middle crust also contributes to the mechanical weakness of plateaus and their buoyancy. In addition, magmatism from the underlying mantle wedge can further sustain the life of these extensive partial melting zones. Additional, much deeper melt accumulation zones exist close to the bottom of these thick-crusted domains, but we have much less information about their evolution and chemistry; they are probably similar to the deepest crustal root zones of the frontal arcs.

Titanium isotopes are used as a tracer of magmatic differentiation, crustal evolution, and sediment provenance. The Ti isotope systematics of volcanic island arc systems have been used as a model for the formation of continental crust, however, the behavior of Ti isotopes of rocks and minerals in continental arcs and plutonic differentiation sequences has not yet been closely examined. The behavior of Ti isotopes in plutonic systems may deviate from volcanic systems due to distinct mineral assemblages and differentiation histories. Consequently, island arcs may fail to capture the full spectrum of Ti isotope variability linked to the processes that generate and differentiate crust in continental arc systems. To test this hypothesis, we conducted Ti isotope measurements of five whole rocks which lie in the compositional range of 50 to 75 wt% SiO2 and their Ti-bearing minerals (titanite, biotite, hornblende, magnetite) from the geochemically well-characterized calc-alkaline Tuolumne Intrusive Complex in eastern California, USA. The whole rock samples yield delta 49Ti values that increase from +0.033 +/- 0.030 %o (95 % CI) to +0.619 +/- 0.025 %o (95 % CI). Titanite and magnetite mineral separates yield delta 49Ti values that are up to 0.37 %o lower than the whole rock, while biotite and hornblende yield delta 49Ti values that are within uncertainty of, or up to 0.25 %o higher than the whole rock. Inter-mineral Ti isotope fractionation reveals that titanite may fractionate Ti isotopes to an extent comparable with magnetite, whereas biotite and hornblende preferentially incorporate isotopically heavy Ti. The high fO2 and fH2O conditions characteristic of continental arcs can favor titanite over Fe-Ti oxides as the primary host of Ti and the fractional crystallization of the former is interpreted to be the primary driver of Ti isotope fractionation in the Tuolumne magmas. However, the petrographic relationships between titanite and other Ti-bearing phases indicates that re-equilibration of Ti among minerals in long-lived plutonic systems can lead to complex Ti isotope fractionation mechanisms. Our data shows that Ti removal and fractionation imparted by mineral crystallization for the Tuolumne system can be described with a net fractionation factor of-0.18 %o, which is congruous with calc-alkaline island arcs, despite the observation that Ti fractionation here is controlled by a different Ti phase. This investigation may provide insights into the Ti isotope systematics of ancient continental crust, where complete differentiation sequences are absent, thereby improving our ability to interpret such data.

New zircon U-Pb geochronology, zircon geochemistry, and whole rock geochemistry are presented from the Magdalena granites in northern Sonora, Mexico that outcrop in the footwall of the Magdalena-Madera metamorphic core complex. Crystallization ages of the Magdalena granites are predominantly Eocene (51 to 38 Ma; n = 21) with two Paleocene ages (60 and 59 Ma). These ages are generally younger than subduction-related magmatism associated with the Cretaceous Eocene Mexican Magmatic Arc (CEMMA) in the northern Mexican Cordillera, including new ages (72 to 61 Ma; n = 8) from this study. The Magdalena granites are also mineralogically, compositionally, and texturally distinct from CEMMA rocks. The granites are moderately peraluminous, two-mica + garnet leucogranite (> 70 wt. % SiO2), relatively depleted in LREE and enriched in HREE, and have major and trace element chemistry consistent with water-absent, muscovite-to biotite-dehydration melting of metasedimentary to metaigneous protoliths. Zircon from the Magdalena granites have high U/Th ratios (median = 11.5) compared to CEMMA zircon (U/Th < 5) and are relatively enriched in HREE compared to CEMMA zircon. The results of this study suggest that the Magdalena granites are anatectic in origin and are part of the North American Cordilleran Anatectic Belt. The Magdalena granites crystallized from evolved melts that underwent early feldspar crystallization and were separated from a feldspar-rich residue, presumably a migmatitic source deeper in the crust. Field and petrographic relationships suggest the Magdalena granites intruded into relatively hot crust, including host rock mushes that exhibit evidence for melt infiltration and disaggregation.

Late Cretaceous to Eocene deformation, magmatism, mineralization, and sedimentation in the southern United States and northern Mexican Cordillera, the Borderland, is commonly attributed to the Laramide orogeny. However, apart from timing, this region shares few unequivocal similarities with the archetypal Laramide orogeny in the central to southern U.S. Rocky Mountain region and is difficult to reconcile with some tectonic and geodynamic models. The most diagnostic characteristics of the Laramide orogeny, including large basement-involved uplifts within a broken retroarc foreland basin, sedimentation in broad perimeter basins, and the cessation of magmatism, are not readily observed in the southwestern United States and northwestern Mexico. On a regional scale, this part of the Cordillera exhibits features consistent with a classic orogenic wedge, including deeper structural levels exposed in the hinterland and deformation progressively moving up structural-stratigraphic section toward the foreland. The age of deformation, regional orientation of structures, spatiotemporal patterns of magmatism and mineralization, and commonality of hinterland features suggest that the Borderland orogenic wedge may be a continuation of the Mexican orogen, the southernmost segment of the North American Cordillera. La deformación, el magmatismo, la mineralización y la sedimentación del Cretácico tardío al Eoceno en la Cordillera del sur de los Estados Unidos y el norte de México, a lo largo de la Frontera, se atribuyen comúnmente a la Orogenia Laramide. Sin embargo, aparte del tiempo, esta región comparte pocas similitudes con la orogenia arquetípica de Laramide en la región de las Montañas Rocosas del centro al norte de Estados Unidos y es difícil de conciliar con muchos modelos tectónicos y geodinámicos. Las características más diagnósticas de la orogenia Laramide, incluidos grandes levantamientos con basamento en una cuenca de retroarco fragmentada, amplias cuencas perimetrales que sobreimprimen la cuenca de antepaís de retroarco anterior y el cese del magmatismo, no se observan en el suroeste de Estados Unidos y el noroeste de México. A escala regional, esta parte de la Cordillera exhibe características consistentes con una cuña orogénica clásica que incluye niveles estructurales más profundos, expuestos en el interior y una deformación que avanza progresivamente hacia la sección estructural-estratigráfica del antepaís. La edad de deformación, la orientación regional de las estructuras, los patrones espaciotemporales del magmatismo y las características comunes del interior sugieren que la cuña orogénica fronteriza continúa en el orógeno mexicano, la terminación meridional de la Cordillera norteamericana.

Table S1: Sandstone petrography data. Table S2: Zircon U-Pb geochronology data.

Understanding the critical processes that lead to lithium (Li) enrichment is essential for the exploration and development of Li resources-a key component of "low-carbon" energy. The Ke'eryin-Taiyanghe plutons in central China provide a unique opportunity to investigate Li mineralization. The Ke'eryin pluton, a potential parental magma for spodumene-bearing pegmatites, consists of porphyritic biotite granite (KBG) and two-mica granite (KTMG), which crystallized at similar to 209 Ma and similar to 202 Ma, respectively. Sr-Nd-Hf-O isotopic compositions suggest that metasedimentary rocks and basaltic basement rocks were the major sources of the Ke'eryin pluton. A positive correlation between Li content in zircons and their delta O-18 values suggests that assimilation of metasedimentary rocks played a significant role in Li enrichment. The KBG is composed primarily of cumulate phases, whereas the KTMG represents the residual melt that underwent Li-rich melt extraction. Consequently, the Ke'eryin pluton cannot represent the parental magma composition of spodumene-bearing pegmatites. The Taiyanghe pluton consists of diorite (TD) and granodiorite (TG), which crystallized at similar to 210-212 Ma. The TD originated from partial melting of an enriched lithospheric mantle, as indicated by its enriched isotopic signatures. The TG was derived from partial melting of tholeiitic basaltic rocks and metasedimentary rocks. Pressure-temperature estimates indicate the existence of a high geothermal gradient during the Late Triassic, which facilitated crustal assimilation and prolonged magmatic fractionation. We propose that high geothermal gradients are an essential factor in promoting Li-enrichment in magmas. A global compilation of major Li-pegmatite deposits and high-temperature/pressure metamorphic events reveals a close spatiotemporal correlation.

We investigated the Wood Mountain fault and the Show Goat formation in the northern Chiricahua Mountains in southeast Arizona, USA, to resolve the timing, style, and distribution of Late Cretaceous to Paleogene contractional deformation in the southern U.S. portion of the North American Cordillera. The Wood Mountain fault is a thin-skinned, low-angle to subhorizontal thrust fault that places Upper Paleozoic carbonate rocks structurally over the Upper Cretaceous to Paleocene Show Goat formation. The Show Goat formation is an similar to 420-m-thick succession of syntectonic clastic and volcanic strata that overlie a prominent angular unconformity above steeply dipping mid-Cretaceous-age rocks of the Bisbee Group. The angular unconformity records initial uplift and erosion related to the onset of regional contractional deformation. New zircon U-Pb data indicate deformation started at ca. 90-73 Ma. The lower Show Goat formation consists of alluvial-fan deposits that formed adjacent to uplifted fault blocks. The upper Show Goat formation records the development of a local volcanic center and primarily consists of lithic tuffs, ash-rich mudstones interpreted as volcanic mudflows, and andesitic lava flows and ash-flow tuffs. New detrital and igneous zircon U-Pb geochronology data constrain deposition of the Show Goat formation between 73 Ma and 63 Ma. New zircon U-Pb data from volcaniclastic deposits of the Bobcat Hill Formation in the Peloncillo Mountains, New Mexico, USA, located similar to 30 km east of the Chiricahua Mountains, indicate regional volcanism and syntectonic sedimentation started ca. 80 Ma. A compilation of regional syntectonic deposits suggests that Late Cretaceous to Paleogene contractional deformation cannot be characterized by a single deformation front propagating toward the foreland. Locally, deformation may have been out-of-sequence or episodic. Syntectonic basins in southeast Arizona and southwest New Mexico were relatively small and localized, formed within an actively deforming orogenic wedge, and were not part of a spatially continuous basin or depocenter.

Late Cretaceous to Paleogene contractional deformation in the southern U.S. Cordillera is commonly attributed to the Laramide Orogeny, in part because of the prevalence of moderate- to high-angle, basement-involved reverse faults. However, it is unclear if the tectonic models developed for the archetypal Laramide foreland belt in the U.S. Rocky Mountain region are applicable to the southern U.S. Cordillera. New geologic mapping of the northern Chiricahua Mountains in southeast Arizona, USA, indicates the presence of an originally sub-horizontal thrust fault, the Fort Bowie fault, and a thinskinned ramp-flat thrust system that is offset by a younger thrust fault, the Apache Pass fault, that carries basement rocks. Crosscutting relationships and new geochronologic data indicate deformation on both faults occurred between 60 Ma and 35 Ma. A biotite 40Ar/39Ar plateau age of 48 Ma from the hanging wall of the basement-involved Apache Pass fault is interpreted to record erosion related to reverse fault movement and rock uplift. The presence of thrust faults in southeast Arizona raises the possibility of a latest Cretaceous-Eocene retroarc orogenic wedge that linked the Sevier and Mexican thrust belts to the north and south, respectively. Basement-involved deformation does not rule out the presence of a retroarc wedge, and many Cordilleran orogenic systems include basement-involved thrusting.

Includes zircon U-Pb LA-ICP-MS data, zircon (U-Th)/He data, apatite (U-Th)/He data, and biotite Ar/Ar data.

Recent advancements in quantitatively estimating the thickness of Earth's crust in the geologic past provide an opportunity to test hypotheses explaining the tectonic evolution of southern Tibet. Outstanding debate on southern Tibet's Cenozoic geological evolution is complicated by poorly understood Mesozoic tectonics. We present new U-Pb geochronology and trace element chemistry of detrital zircon from modern rivers draining the Gangdese Mountains in southern Tibet. Results are similar to recently published quantitative estimates of crustal thickness derived from intermediate-composition whole rock records and show similar to 30 km of crustal thinning from 90 to 70 Ma followed by thickening to near-modern values from 70 to 40 Ma. These results extend evidence of Late Cretaceous north-south extension along strike to the west by similar to 200 km, and support a tectonic model in which an east-west striking back-arc basin formed along Eurasia's southern margin during slab rollback, prior to terminal collision of India with Eurasia.

The Pinaleno Mountains of southeastern Arizona is the eastern-most metamorphic core complex in the southern U.S. and northern Mexican Cordillera. This study investigates the thermal history and exhumation record of the Pinaleno core complex using mica 40Ar/39Ar, apatite and zircon (U-Th)/He, and apatite fission-track thermochronometers. The Pinaleno Mountains experienced two periods of rapid cooling during the Cenozoic. The first period, from ca. 27 to 21 Ma, records tectonic exhumation related to the development of the core complex and extensional shear zone. This period was followed by a relatively quiescent interval from 21 to 13.5 Ma that records little to no exhumation. The second period of rapid cooling, from 13.5 to 11 Ma, records tectonic exhumation related to high-angle normal faulting, characteristic of the Basin and Range province. The exhumation timing of the Pinaleno core complex matches previously recognized spatiotemporal trends in the southern Basin and Range province and indicates that core complex exhumation in this region started in southeastern Arizona (ca. 32-33 degrees N) and migrated both northward and southward. These trends correlate well with the latitude and timing of subduction of the Pacific-Farallon spreading ridge and the migration of the Mendocino (northward) and Rivera (southward) triple junctions. Spatiotemporal core complex exhumation trends also correlate well with regional magmatism associated with the mid-Cenozoic flare-up, including syn-extensional intrusive rocks found in the footwalls of core complexes. New thermochronologic data constrain rapid exhumation of the Pinaleno metamorphic core complex to ca. 27-21 Ma The Pinaleno Mountains experienced renewed tectonic exhumation from 13.5 to 11 Ma during Basin and Range-style extension Plate margin dynamics and local magmatism exert a primary influence on spatiotemporal patterns of core complex exhumation

The southern US and northern Mexican Cordillera experienced crustal melting during the Laramide orogeny (c. 80-40 Ma). The metamorphic sources of melt are not exposed at the surface; however, anatectic granites are present throughout the region, providing an opportunity to investigate the metamorphic processes associated with this orogeny. A detailed geochemical and petrochronological analysis of the Pan Tak Granite from the Coyote Mountains core complex in southern Arizona suggests that prograde metamorphism, melting, and melt crystallization occurred here from 62 to 42 Ma. Ti-in-zircon temperatures (TTi-zr) correlate with changes in zircon rare earth elements (REE) concentrations, and indicate prograde heating, mineral breakdown, and melt generation took place from 62 to 53 Ma. TTi-zr increases from similar to 650 to 850 degrees C during this interval. A prominent gap in zircon ages is observed from 53 to 51 Ma and is interpreted to reflect the timing of peak metamorphism and melting, which caused zircon dissolution. The age gap is an inflection point in several geochemical-temporal trends that suggest crystallization and cooling dominated afterward, from 51 to 42 Ma. Supporting this interpretation is an increase in zircon U/Th and Hf, a decrease in TTi-zr, increasing zircon (Dy/Yb)(n), and textural evidence for coupled dissolution-reprecipitation processes that resulted in zircon (re)crystallization. In addition, whole rock REE, large ion lithophile elements, and major elements suggest that the Pan Tak Granite experienced advanced fractional crystallization during this time. High-silica, muscovite +/- garnet leucogranite dikes that crosscut two-mica granite represent more evolved residual melt compositions. The Pan Tak Granite was formed by fluid-deficient melting and biotite dehydration melting of meta-igneous protoliths, including Jurassic arc rocks and the Proterozoic Oracle Granite. The most likely causes of melting are interpreted to be a combination of (1) radiogenic heating and relaxation of isotherms associated with crustal thickening under a plateau environment, (2) heat and fluid transfer related to the Laramide continental arc, and (3) shear and viscous heating related to the deformation of the deep lithosphere. The characteristics and petrologic processes that created the Pan Tak Granite are strikingly similar to intrusive suites in the Himalayan leucogranite belt and further support the association between the North American Cordilleran anatectic belt and a major orogenic and thermal event during the Laramide orogeny.

An ongoing question in understanding the evolution of the Himalayan-Tibetan orogeny is how much of the observed upper crustal shortening and crustal thickness is related to the Cenozoic collision between India and Asia vs earlier tectonic events along the southern margin of Asia. While the Pamir Mountains located at the western end of the orogen have been proposed to have experienced significant Cenozoic shortening, recent studies have interpreted upper crustal shortening to be primarily mid- to Late Cretaceous. To further understand the timing of upper crustal deformation in the Pamir, we investigated synorogenic clastic deposits within the footwall of the north-dipping Tanymas thrust fault along the suture between the Northern and Central Pamir terranes. Sandstones from these deposits were analyzed by detrital zircon U-Pb, zircon fission track, and muscovite 40Ar/39Ar analyses to assess the age and source of the detritus. Results show the deposits were sourced from the Northern Pamir (hanging wall of the Tanymas thrust) and provide an Early Cretaceous maximum deposition age of ∼130–120 Ma, interpreted to constrain their age and date motion on the Tanymas thrust fault as Early Cretaceous. Our results, integrated with previous studies, show Cretaceous deformation in the Pamir began in the Northern Pamir (∼140–110 Ma) before sweeping into the Southern Pamir in the mid- to Late Cretaceous (∼110–75 Ma). These results are consistent with previous interpretations of an Early Cretaceous phase of shallow- or flat-slab northward subduction followed by slab rollback and southward migration of deformation and magmatism in the mid- Cretaceous.

The uplift history of the Pamir-Tian Shan orogens remains debated, and is crucial to understanding the aridification of Central Asia. To address this question, we performed inverse modeling of the westward-flowing Vakhsh River along the Alai Valley between the Pamir and Tian Shan orogens. We validated the application of this method in reconstructing uplift history of mountains with complex climatic and tectonic settings. The modeled results reveal three episodes of accelerated uplift of the Vakhsh River drainage at ca. 10-7 Ma, ca. 5 Ma, and 2-0 Ma. The late Miocene rapid uplift at rates of 0.6-0.8 mm/yr of the Vakhsh River drainage occurred at ca. 10-7 Ma. Rock uplift, coeval with compressional deformation and exhumation around the Alai Valley, was likely driven by crustal shortening during the Pamir-Tian Shan convergence. Narrowing of the Alai Valley started to impact westerly atmospheric flow, leading to incipient rain shadow responsible for emergence of desert in the proximal leeward Tarim Basin. Accelerated uplift at ca. 5 Ma and 2-0 Ma at rates of 1.0-1.4 mm/yr and 1.7-2.3 mm/yr, increased surface elevations to near modern heights (3.5-5 km) that largely blocked the westerlies, causing enhanced aridification in the Tarim Basin. Our modeling results highlight the important role of mountain building in shaping late Cenozoic climate in Central Asia.

New thermochronologic and microstructural data from the Quitobaquito Hills provide insight into conditions of deformation in the middle crust of southwestern Arizona during Late Cretaceous to early Paleogene crustal shortening associated with low angle subduction. The mylonitic Quitobaquito shear zone juxtaposes Paleoproterozoic (~1.6 Ga) gneiss and schist structurally above Jurassic (175–170 Ma) meta-volcanic and meta-volcaniclastic rocks. The shear zone dips ~50° SSE and exhibits top-to-the-north, reverse-sense kinematics based on mineral (quartz) stretching lineations in outcrop and σ-type and domino-type fragmented porphyroclasts, mica fish, and S-C fabrics in thin section. The main shear zone is ~30 m thick and underlain by at least one footwall imbricate in the Jurassic sequence. Argon-argon and zircon (U-Th)/He thermochronologic data from the footwall and hanging wall of the shear zone reveal distinct time-temperature paths from approximately 70 to 55 Ma, interpreted to represent the timing of displacement on the shear zone. From ~55 Ma to present, both blocks of the shear zone experienced similar exhumation histories, including a period of moderate cooling during Eocene time. Quartz and feldspar recrystallization fabrics and deformation mechanisms bracket deformation temperature between 450–600°C, consistent with thermochronologic data and greenschist- to lower-amphibolite-facies mineral assemblages in the Jurassic metamorphic rocks. Local metamorphic foliations are parallel to the Quitobaquito shear zone and metamorphism of footwall rocks is interpreted as synkinematic with the shear zone. The timing and kinematics of the Quitobaquito shear zone indicate that it is an expression of Laramide contractional tectonism in southwestern Arizona. We did not find structural or thermochronological evidence to suggest that the shear zone is a reactivated strand of the postulated Jurassic Mojave-Sonora megashear.

Eastern Myanmar is located at the junction of the Changning-Menglian and Chiang Rai-Chiang Mai zone and is a crucial region for constraining the evolution of the eastern Paleo-Tethys. This study presents new zircon U-Pb geochronological, mineral and whole-rock geochemical, and Sr-Nd-Hf-O isotopic data for magmatic rocks from the Sukhothai arc in eastern Myanmar. The rock suites analyzed include 360-355 Ma basaltic rocks and trondhjemitic dikes, and 257-254 Ma volcanic rocks and gabbroic cumulates. The basaltic rocks were derived from partial melting of me ' lange pair with peridotite and experienced assimilation and fractional crystallization (AFC). The trondhjemitic dikes were formed by partial melting of the basaltic rocks and experienced fractional crystallization at shallow depth. We suggest that andesite and dacite were derived from partial melting of depleted mantle wedge and underwent AFC process. The gabbroic cumulates are a crystallizing phase associated with the melts that produced the coeval volcanic rocks. We propose that eastern Myanmar, Central Tibet, SW Yunnan and Southeast Asia share a similar three-staged magmatic history, forming a ~ 4000 km long magmatic belt. Stage I records the magmatic events related to subduction of the eastern Paleo-Tethys Ocean during the Early Carboniferous. A back-arc basin was opened during the Late Carboniferous, and extensive subductionrelated magmatism was followed since the Permian. Stage II records the igneous rocks formed during the final amalgamation between the Indochina and Sibumasu Blocks during the Late Permian to Middle Triassic. Stage III is defined by the post-collisional magmatism distributed across the suture zone during the Late Triassic.

Abstract The mechanisms driving crustal deformation and uplift of orogenic plateaus are fundamental to continental tectonics. Large‐scale crustal flow has been hypothesized to occur in eastern Tibet, but it remains controversial due to a lack of geologic evidence. Geochemical and isotopic data from Cenozoic igneous rocks in the eastern Tibet‐Gongga‐Zheduo intrusive massif, provide a way to test this model. Modeling results suggest that Cenozoic magmas originated at depths of ∼30–40 km, the depth that crustal flow has been postulated to occur at. Detailed isotopic analyses indicate that the igneous rocks are derived from partial melting of the local Songpan‐Ganzi crust, arguing against a long‐distance crustal flow. Episodic magmatism during the Cenozoic showing a repeated shifting of magmatic sources can be correlated with crustal uplift. The continued indentation of the Indian Block and upwelling of the asthenosphere contribute to the crustal deformation, magmatism, and uplift.