Bimodal volcanism is common across intracontinental rifts. However, tectonic controls on the composition of synextensional volcanism remain inadequately understood. In this study, we examined the spatial distributions of late Cenozoic faults and volcanic centers throughout the active Owens Valley rift basin (California, USA) in the western Basin and Range province of North America. Based on synthesized structural, topographic, geophysical, and geochemical observations, we suggest that the 3-D geometries of major faults in Owens Valley control the location, volume, residence time, and composition of synextensional volcanism. Specifically, northern and southern Owens Valley are wide, asymmetric grabens where master, listric normal faults have breakaways on one basin margin and extend beneath the opposing margin. Beneath opposing basin margins, master faults have thinned the lithosphere, creating space for decompression melting and enabling mantle melt to ascend into the crust in large volumes. Crustal dilatation and increased permeability allowed for some melt to stall and develop felsic compositions, whereas other mafic melt ascended with limited compositional change, resulting in bimodal volcanism. The asymmetric grabens in the north and south transition to a narrow, symmetric graben in central Owens Valley featuring high-angle, basin-bounding normal faults. There, normal and strike-slip faults serve as conduits for mafic melt to rapidly ascend with minimal wall rock contamination and compositional change. Our model linking rift-fault geometry to the location, volume, residence time, and composition of synextensional volcanism may apply to other intracontinental rifts with similar relationships.

Early Paleozoic plutonism and metamorphism in the Cenozoic Himalayan orogen is correlated with tectonomagmatic events that impacted the margins of the Gondwanan continent. Deciphering the tectonic origin of these Cambrian-Ordovician intrusions is important to better understand the evolution of the Gondwanan and Eurasian continents and initial conditions for Cenozoic Himalayan construction. To address these issues, we integrated geologic observations, whole-rock and Sr-Nd isotope geochemistry, and igneous and detrital zircon geochronology in the Himachal Himalaya along the Chenab, Pin, Sutlej, and Baspa river valleys in northwestern India. The goals of this study are to constrain: (1) the pre-Himalayan tectono-stratigraphic framework of the proto-Tethyan margin; and (2) the geodynamic setting for early Paleozoic peri-Gondwana crustal melting. Geologic, geochronologic, and geochemical data show that ca. 495-463 Ma crustal-derived peraluminous magmas crystallized at moderate to shallow crustal levels, synchronous with a regionally extensive Cambrian-Ordovician hiatus in sedimentation. Cambrian-Cretaceous strata in the Tethyan Himalaya show similar detrital zircon age distributions and evidence of a consistent provenance source via an extensive fluvial system over a broad area of eastern Gondwana. These results, combined with observed structural continuity across the Cambrian-Ordovician unconformity, suggest that the source area for the northern Greater India passive margin did not significantly change due to peri-Gondwanan orogenesis. New and compiled geologic observations, wholerock and Sr-Nd isotope geochemistry, and igneous and detrital zircon geochronology are consistent with global Paleozoic S-type magmatism along the margins of Gondwana, which may be explained by multiple or a single peri-Gondwanan silicic Large Igneous Province.

Although climate can strongly influence erosional efficiency (i.e., erosion rate for a given topography), demonstrating its impact in tectonically active areas has been challenging due to other confounding controlling factors, such as lithology. Here, we show that 10Be-derived erosion rates and efficiencies in the Himalayan orogen exhibit distinct relationships with climatic factors depending on lithology. We compile 173 10Be-derived, basin-averaged erosion rates across the orogen, including 12 newly measured rates from the Dibang and Lohit valleys in the easternmost Himalaya, regions characterized by high precipitation magnitudes and variability. We group basins based on lithologies separated by orogen-scale thrust faults and quantify erosional efficiency coefficients based on the relationships between erosion rates and topographic metrics. Our results show that erosion rates and erosional efficiency from sedimentary and metasedimentary rocks along the Himalayan range front display a positive, nonlinear correlation with climatic factors, such as the number of extreme rainfall events and mean annual precipitation rates. In contrast, erosion rates from crystalline lithologies in the hanging wall of the Main Central thrust show a strong correlation with fluvial topography, whereas erosional efficiency shows no statistically significant correlation with climatic factors. Rapid erosion rates and high erosional efficiencies in the eastern Himalayan range front are likely driven by extreme precipitation on tectonically active, steep slopes composed of mechanically weak metasedimentary rocks. Our findings highlight the importance of the interplay between controlling factors, which include tectonics, lithology, and climate, that drive surface erosion and influence the topographic evolution of orogenic systems.

The southeastern Tibetan Plateau has been a key area for Cenozoic deformation and orogenic expansion during India-Asia convergence. Yet, its tectonic and exhumation histories remain inadequately understood. In addition, significant debate has focused on whether lateral growth of the plateau was controlled by continental-scale, discrete faulting and/or lower crustal flow. To address these questions for the southeastern Tibetan Plateau, we performed field mapping and low-temperature thermochronology across the Tengchong and Baoshan blocks and along the Gaoligong and Chongshan shear zones. Cooling ages and thermal history models indicate that the region experienced at least four distinct cooling phases since the Miocene: ca. 18-10 Ma, ca. 7-5 Ma, and ca. 5-2 Ma. The Early to Middle Miocene (ca. 18-10 Ma) phase is characterized by greater and more rapid cooling and thus, dominated the exhumation history of the southeastern Tibetan Plateau margin. Ca. 18-10 Ma cooling is interpreted to be associated with oblique slip along the Gaoligong shear zone. Regional cooling from ca. 15-10 Ma was likely driven by lower crustal flow. Late Miocene (ca. 7-5 Ma) cooling was restricted to areas featuring deep river incision, suggesting influences from topography and enhanced erosion. Pliocene-early Pleistocene (ca. 5-2 Ma) cooling is linked to fault activity and volcanism associated with Indian slab dynamics beneath the Myanmar subduction zone. Our results also suggest that the lateral expansion of the southeastern Tibetan Plateau was driven by both continental-scale shear and lower-crustal flow rather than a singular dynamic mechanism.

In his classic contribution “A Heat Pipe Mechanism for Volcanism and Tectonics on Venus” [1989, JGR 94, B3, 2779-2785], Turcotte applied O’Reilly and Davies’ [1981, GRL 8, 313-316] model for Io’s volcanic heat transport to Venus, and further speculated that this mechanism might explain a thick lithosphere inferred for Archean Earth. The latter idea – to consider heat-pipe cooling for Earth – then lay fallow until roughly 15 years ago, when one of us (Moore) argued in talks and manuscripts (all rejected) that the cold, thick, and strong lithosphere generated by heat-pipe cooling might offer an alternative to subduction tectonics for generating the “too-cold” Hadean zircons reported by Hopkins et al. [2008, Nature 456, 493-496]. With the additional realization that the heat-pipe cooling mechanism might similarly account for the rocks preserved from the first half of Archean time, the concept of an early heat-pipe Earth finally received broad consideration just over a decade ago [Moore & Webb, 2013 Nature 501, 501-505]. Heat-pipe cooling is a hot stagnant-lid cooling mode based on our understanding of the active volcano-tectonics of Jupiter’s moon Io [O’Reilly & Davies, 1981]. Heat-pipes are not plumes: heat-pipes are conduits channeling melts upwards through lithosphere, whereas plumes commonly span the whole crust and mantle and accordingly have relatively complex histories. The heat-pipe Earth hypothesis posits that during the first third of Earth history, rapid volcanism dominated cooling from the end of the magma ocean period to the onset of (episodic?) plate tectonics. During the heat-pipe period, voluminous mafic volcanism resulted in protracted resurfacing, causing quasi-continuous burial of cold, hydrated surface materials that (1) cooled a single-plate lithosphere and (2) generated tonalite-trondhjemite-granodiorite melts deep in the lithosphere. It is noteworthy that the burial of surface materials to mantle depths – long seen as a distinguishing characteristic of plate tectonics – is a hallmark of heat-pipe cooling. The past decade has seen abundant explorations and tests of the heat-pipe Earth hypothesis, as well as renewed interest in the heat-pipe cooling mechanism for other terrestrial bodies. This presentation will review major results and consider key critiques. Highlights include demonstrations that heat-pipe cooling viably explains: (a) the early histories of the lithospheres preserved at Mercury, Venus, Mars, and the Moon, and thus can be hypothesized as a universal cooling mechanism for early / hot terrestrial bodies in our Solar System and others [Moore et al., 2017 EPSL 474, 13-19; Peterson et al., 2021 Sci.Adv. 7:eabh2482]; (b) the Eoarchean development of the Isua supracrustal belt of southern West Greenland [Webb et al., 2020 Lithosphere 12, 166-179 and a collection of subsequent works], which was previously understood exclusively via plate tectonic models; (c) the initiation of a global plate network, as thinning and corresponding warming of lithosphere during waning heat-pipe cooling caused thermal expansion which overcame the tensional strength of the lithosphere [Tang et al., 2020 Nat.Comm. 11:3621]; and (d) Earth’s detrital zircon depositional records older than ~3.3 Ga [Zuo et al., 2021 EPSL 575:117182].

The Zongwulong Shan-Qinghai Nanshan tectonic belt of the northern Tibet Plateau ex-perienced a protracted tectonic history,including the openings and closures of the Proto-and Paleo-Tethyan Oceans.Although the tectonic belt has been extensively studied,details regarding the tectonic processes involved in its development remain controversial.To better constrain the tec-tonic processes of this tectonic belt,we conducted detailed field geological mapping,zircon U-Pb geochronology,and whole-rock geochemical and Sr-Nd isotopic analyses.Our results show that in-trusive rocks in the tectonic belt crystallized in ca.292-233 Ma,perhaps in an arc/subduction set-ting.Geochemical and Sr-Nd isotopic data suggest that Early Permian-Late Triassic ultramafic-intermediate intrusions were sourced from the enriched mantle,whereas intermediate-acidic rocks were sourced from mixed crust-mantle.We present the tectonic model that involves:(1)Early Devo-nian-Early Permian intracontinental extension occurred in the northern margin of the Qaidam conti-nent(ca.416-292 Ma);(2)Early Permian-Late Triassic northward subduction of the Paleo-Tethyan Ocean resulted in arc magmatism(ca.292-233 Ma);and(3)subsequent Late Triassic intraconti-nental extension(ca.233-215 Ma).Our results suggest that the Late Paleozoic-Early Mesozoic de-velopment of the Zongwulong Shan-Qinghai Nanshan was related to the opening,subduction,and slab retreat of the Paleo-Tethyan Ocean,which has key implications for the tectonic evolution of the northern Tibetan Plateau.

The growth and evolution of the South China continent involved multiple, progressive tectonic processes during the Phanerozoic, including early Paleozoic orogeny and Mesozoic plate-margin activity associated with the Paleo-Tethyan and Paleo-Pacific oceanic realms. These overprinting tectonic events resulted in complicated rock assemblages and deformation patterns. The construction of the southeastern South China continent remains poorly understood particularly because early Paleozoic tectonism was modified by Mesozoic magmatism and deformation. In this study, we investigated the geology of the Wugong Shan region within the South China continent, which has experienced a protracted tectonic evolution since the Neoproterozoic. We combined new and published field observations, geochronological results, and geochemical and Sr-Nd isotopic data to constrain the chronostratigraphic framework and timing of Phanerozoic magmatism. Detrital zircon U-Pb results for thermal-contacted metasedimentary rocks suggest that Neoproterozoic-Ordovician strata were metamorphosed by the intrusion of early Paleozoic granitoids. Zircon U-Pb, whole-rock geochemical, and Sr-Nd isotopic results show that the Wugong Shan region experienced two dominant stages of magmatism at ca. 467-417 Ma and ca. 168-149 Ma. These stages involved the genera tion of S-type granites via partial remelting of Archean-Proterozoic continental crust. We integrated these results into a revised model for the Paleozoic-Mesozoic tectonic evolution of the Wugong Shan, which initially involved Middle Ordovician-Silurian intracontinental deformation associated with early Paleozoic plate-margin tectonic activity along the Wuyi-Yunkai orogenic belt in the South China continent. This was followed by the Triassic collision of the South and North China continents and Jurassic-Cretaceous plate-margin magmatic activity during the westward subduction of the Paleo-Pacific oceanic slab. The Wugong Shan is a Jurassic magmatic-metamorphic dome that formed locally and was exhumed due to subductionrelated magmatism.

The Isua and Tussaap supracrustal belts of the Itsaq gneiss complex, southwestern Greenland, form the largest and best-preserved exposure of Eoarchean supracrustal materials on Earth. Previous studies have almost exclusively focused on the ∼35-km-long, arc-shaped Isua supracrustal belt and adjacent ca. 3.8–3.7 Ga meta-tonalite bodies, which are the basis for competing Archean tectonic regime interpretations (i.e., plate versus heat-pipe tectonics). In this study, we performed geologic field mapping of the seldom-explored Tussaap supracrustal belt, located ~11 km south of the Isua supracrustal belt, to better constrain its litho-structural framework and test the predictions of existing Eoarchean tectonic models. Observations from this study and previous works show that the Tussaap supracrustal belt consists of a east-northeast-striking, ~12-km-long and

The growth and evolution of the Eurasian continent involved the progressive closure of major ocean basins during the Phanerozoic, including the Tethyan and Paleo-Asian oceanic realms. Unraveling this complicated history requires interpreting multiple overprinted episodes of subduction-related magmatism and collisional orogeny, the products construction of the Himalayan-Tibetan orogen due to the India-Asia collision. In particular, the tectonic evolution of northern sin is poorly resolved due to several phases of Phanerozoic orogeny that have been reactivated during the Cenozoic deformation. In this study, we investigated the geology of the northern Qaidam continent, which activity associated with the development of the Eastern Kunlun orogen to the south and the Qilian orogen to the north. We combined new and published field observations, geochronologic and thermochronologic ages, and geochemical data to construct regional associated with oceanic subduction and continental collision. Results suggest that the phases of subduction magmatism and collision. First, a Cambrian-Ordovician magmatic arc developed in the northern Qaidam continent due to south-dipping subduction. This phase was followed by the closure of the Qilian Ocean and the collision of the resulting in Silurian-Devonian orogeny and the development of a regional unconformity across northern Tibet. A subsequent Permthe northern Qaidam continent due to northdipping subduction. This phase was followed by the closure of the Neo-Kunlun Ocean and the south and Qaidam continent. These interpretations are incorporated into a new and formation of northern Tibet and the Eurasia continent.

The nature of Precambrian metamorphic basement rocks and overall tectonic evolution of the Qaidam block in northern Tibet remains debated despite being important to understanding the assembly of Asia. Paleogeographic reconstructions of Precambrian supercontinents rarely consider Phanerozoic tectonic modification of its constituent Precambrian blocks. This issue is particularly relevant for the Qaidam block and its neighboring crustal fragments, which experienced significant Phanerozoic overprinting from multiple tectonic episodes. To address this problem, we systematically reviewed key geological observations and regional datasets related to Proterozoic magmatism, metamorphism, and sedimentation of major Precambrian blocks in China. This synthesis provided new constraints on the Proterozoic tectonic evolution of the Qaidam block, including paleogeographic supercontinent configurations and nature of multiple continental-drift-collision events. New results of field mapping, geochronological, and geochemical analyses allow us to divide the Precambrian rocks of the Qaidam block into four divisions: (1) Paleoproterozoic gneiss and schist; (2) Meso- and (3) Neoproterozoic metasedimentary rocks; and (4) Proterozoic intrusions. We propose that the Qaidam block was part of a “Greater North China” block, which experienced early Paleoproterozoic post-collisional extension and continental collision along the Paleoproterozoic Northern Margin orogen to form the Columbia-Nuna supercontinent. The Greater North China block subsequently experienced Mesoproterozoic extension related to supercontinent breakup. In addition, we propose that the Greater North China block was affixed to the western margin of Laurentia and Siberia as part of Rodinia in the Neoproterozoic, rifted in the late Neoproterozoic, and drifted in the early Paleozoic as a series of microcontinents.

The construction of Earth’s largest highland, the Tibetan Plateau, is generally considered to have been generated by the Cenozoic India-Asia collision. However, the extent to which high topography existed prior to the Cenozoic remains unclear. The Hexi Corridor foreland basin of the northern Tibetan Plateau is an ideal region in which to investigate this history, given its widespread exposure of Early Cretaceous sedimentary sequences. In this study, we examined the Early Cretaceous strata in the northern Hexi Corridor to understand the relationships between pre-Cenozoic sedimentation and tectonic deformation and constrain the late Mesozoic tectonic setting of the adjacent Qilian Shan and Alxa blocks bordering the northern Tibetan Plateau. Results of sandstone petrology analyses, paleocurrent observations, and U-Pb geochronology suggest that the oldest Early Cretaceous sediments deposited in the northern Hexi Corridor were sourced from the southern Alxa block during the earliest Cretaceous. By the late Early Cretaceous, Hexi Corridor sediments were sourced from both the southern Alxa block to the north and the Qilian Shan to the south. Sandstone petrologic results indicate that the northern Hexi Corridor experienced a tectonic transition from contraction to extension during the Early Cretaceous. These findings suggest that the northern Tibetan Plateau region was partially uplifted to a high elevation during the late Mesozoic before the India-Asia collision.

The northwest-trending Altai Mountains of central Asia expose a complex network of thrust and strike-slip faults that are key features accommodating intracontinental crustal shortening related to the Cenozoic India-Asia collision. In this study, we investigated the Quaternary slip history of the Fuyun fault, a right-lateral strike-slip fault bounding the southwestern margin of the Altai Mountains, through geologic mapping, geomorphic surveying, and optically stimulated luminescence (OSL) geochronology. At the Kuoyibagaer site, the Fuyun fault displaces three generations of Pleistocene-Holocene fill-cut river terraces (i.e., T-3, T-2, and T-1) containing landslide and debris-flow deposits. The right-lateral offsets are magnified by erosion of terrace risers, suggesting that river course migration has been faster than slip along the Fuyun fault. The highest T-p2 terrace was abandoned in the middle Pleistocene (150.4 +/- 8.1 ka uppermost OSL age) and was displaced 145.5 +45.6/-12.1 m along the Fuyun fault, yielding a slip rate of 1.0 +0.4/-0.1 mm/yr since the middle Pleistocene. The lower T-p1 terrace was abandoned in the late Pleistocene and aggraded by landslides and debris flows in the latest Pleistocene-Holocene (36.7 +/- 1.6 ka uppermost OSL age). T-p1 was displaced 67.5 +14.2/-6.1 m along the Fuyun fault, yielding a slip rate of 1.8 +0.5/-0.2 mm/yr since the late Pleistocene. Our preferred minimum slip rate of similar to 1 mm/yr suggests the Fuyun fault accommodates similar to 16% of the average geodetic velocity of similar to 6 mm/yr across the Altai Mountains. Integration of our new Fuyun slip rate with other published fault slip rates accounts for similar to 4.2 mm/yr of convergence across the Chinese Altai, or similar to 70% of the geodetic velocity field.