The Carboniferous-Permian Tarija basin of southern Bolivia evolved under major tectonic and climatic influence. The timing of transition from glacially influenced to arid conditions, after the Gondwanide tectonic event, has been based mainly on palynological correlations. This study presents data from three U-Pb detrital zircon samples (similar to 500 grains each), providing two robust maximum deposition ages (327 +/- 4 and 259 +/- 3 Ma). These results are integrated with stratigraphic cycles defining the Macharet & iacute;, Mandiyut & iacute; and Cuevo Groups. Our interpretation, supported by our data and previous studies, constrains a Mississippian to earliest Pennsylvanian age for the Macharet & iacute; Group and a Pennsylvanian age for the later Mandiyut & iacute; Group, both bounded by the regional Intra-Carboniferous unconformity (similar to 318 Ma). A major depositional hiatus followed the end of glaciation, with arid sedimentation recorded only after the late Permian (Cuevo Group).

Western North America is the archetypical Cordilleran orogenic system that preserves a Mesozoic to Cenozoic record of oceanic Farallon plate subduction-related processes. After prolonged Late Jurassic through mid-Cretaceous normal-angle Farallon plate subduction that produced the western North American batholith belt and retroarc fold-thrust belt, a period of low-angle, flat-slab subduction during Late Cretaceous-Paleogene time caused upper plate deformation to migrate eastward in the form of the Laramide basement-involved uplifts, which partitioned the original regional foreland basin. Major questions persist about the mechanism and timing of flat-slab subduction, the trajectory of the flat-slab, inter-plate coupling mechanism(s), and the upper-plate deformational response to such processes. Critical for testing various flat-slab hypotheses are the timing, rate, and distribution of exhumation experienced by the Laramide uplifts as recorded by lowtemperature thermochronology. In this contribution, we address the timing of regional exhumation of the Laramide uplifts by combining apatite fission-track (AFT) and (UTh-Sm)/He (AHe) data from 29 new samples with 564 previously published AFT, AHe, and zircon (U-Th)/He ages from Laramide structures in Arizona, Utah, Wyoming, Colorado, Montana, and South Dakota, USA. We integrate our results with existing geological constraints and with new regional cross sections to reconstruct the spatial and temporal history of exhumation driven by Laramide deformation from the mid-Cretaceous to Paleogene. Our analysis suggests a two-stage exhumation of the Laramide province, with an early phase of localized exhumation occurring at ca. 100-80 Ma in Wyoming and Montana, followed by a more regional period of exhumation at ca. 70-50 Ma. Generally, the onset of enhanced exhumation occurs earlier in the northern Laramide province (ca. 90 Ma) and later in the southern Laramide province (ca. 80 Ma). Thermal history models of selected samples along regional cross sections through Utah-Arizona-New Mexico and Wyoming-South Dakota show that exhumation occurred contemporaneously with deformation, implying that Laramide basement block exhumation is coupled with regional deformation. These results have implications for testing proposed migration pathway models of Farallon flat-slab and for how upper-plate deformation is expressed in flat-slab subduction zones in general

The Shinarump and Gartra Members form the basal part of the Chinle Formation in western USA and are the deposits of a river system that flowed northwestward from the Ouachita Orogen to the Auld Lang Syne basin during the Late Triassic. Previous estimates of paleoslope for this river have been limited by low numbers of data points. This study, therefore, presents a dataset of 1133 cross-set height measurements to form the basis for paleoslope reconstructions, and as part of a facies analysis which additionally includes clast counts identifying a total of 13,584 clasts, grain-size analyses measuring 7400 grains and paleoflow analyses composed of a further 975 trough cross-sets. Lithofacies analyses describe the Shinarump and Gartra Members as the deposits of a braided river system and identify previously unrecognized antidune deposits at the Vermilion Cliffs, northern Arizona. This suggests that the sandy facies at the top of the Shinarump Member may be deposits of flash flood events. Grain-size and cross-set height analysis allow for estimates of paleoslope to be produced, which range from 9.6 x 10(-5) to 4.3 x 10(-4), with a median value similar to 2.5 x 10(-4), on par with many modern continental scale rivers. These estimates predict that the upper surface of the Chinle basin was similar to 75-150 m above sea level on the Colorado Plateau at its time of deposition. To reveal the amount of subsidence necessary to accommodate the Chinle Formation, we tied a 2-D backstripping analysis to the calculated paleoslope reconstruction. The resulting basin accommodation distribution describes a low-magnitude (hundreds of meters), long-wavelength (>1000 km) deflection, fully compatible with characteristics of dynamic topography. The combination of subsidence analysis with an independent paleoelevation metric can be applied to other members of the Chinle Formation and may be useful in other similar contexts where dynamic topography is difficult to quantify.

The Frontal Cordillera is a first-order geologic feature of the southern central Andes, hosting the highest hinterland topography above the modern Pampean flat-slab segment. The timing of Frontal Cordillera exhumation is important for testing models of Andean tectonics, yet large latitudinal gaps exist between structural and thermochronological constraints for the region. We conducted a thermochronometric study using a 4.4 km age-elevation transect along the northeast ridge of Cerro Mercedario, the highest peak in the La Ramada massif at similar to 32 degrees S. Zircon (U-Th)/He dates indicate partial resetting, supporting a limited magnitude of exhumation in even the most extreme Andean topography. Single grain apatite (U-Th-Sm)/He dates range from 8.5 +/- 0.9 to 35.8 +/- 3.6 Ma, with median dates of similar to 10.5 to similar to 15.7 Ma with increasing elevation. Integrated with geologic mapping and thermal history modeling, these data suggest Early to Middle Miocene exhumation along the Santa Cruz and Espinacito faults concomitant with uplift of the La Ramada massif. New apatite helium data from the Cordillera del Tigre segment of the Frontal Cordillera are partially reset and preferred modeling interpretations suggest exhumation ca. 11-9 Ma, coeval with shortening in the eastward adjacent Precordillera. These data add to accumulating regional evidence for out-of-sequence deformation during the Miocene, consistent with internal (hinterland) growth of a subcritical orogenic wedge contemporaneous with surface uplift and crustal thickening in the south-central Andes.

The Miocene Climatic Optimum (MCO; similar to 17-14 Ma) is one of Earth's most recent protracted warming events and serves as an analog to anthropogenic climate change. Constraining the land surface response to the MCO is critical for paleoclimate model validation and for predictions of future climatic response. However, nonmarine records across the MCO interval are limited. The hinterland and foreland basins of the southern Central Andes in Argentina preserve stratigraphic records across the MCO. These continental deposits record the onset of dune fields at >30 Ma to similar to 19 Ma, with widespread eolian deposition at similar to 22-17 Ma. We document a regional change from eolian dune fields to fluvial and lacustrine conditions at similar to 18-15 Ma, broadly coincident with the MCO, over similar to 1000 km along-strike, in localities that would have occupied both high and low elevation positions and from different tectono-morphic settings. These paleoenvironmental changes are corroborated by new climate model simulations which show increased seasonality and precipitation along the eastern flank of the southern Central Andes during the MCO. Our results support a shift from arid to more humid and seasonal conditions during the MCO in the southern Central Andes, likely driven by intensification of the South American monsoon.

Changes in precipitation can drive major shifts in stratigraphy and fold-thrust belt behavior. We investigate the stratigraphic and orogenic response to pronounced climatic warming during the Middle Miocene Climatic Optimum (ca. 17-14 Ma) in the southern Central Andes. New and compiled stratigraphic and geochronologic data come from depocenters at ~25-35°S; these basins would have occupied both high and low elevation positions during the middle Miocene. Regionally ubiquitous eolianite deposition from ca. 22-17 Ma supports arid conditions on the eastern flank of the Central Andes preceding the Middle Miocene Climatic Optimum. Eolian facies are replaced by fluvial-lacustrine strata near the onset of the Middle Miocene Climatic Optimum over 1000 km along-strike. These results support a change from arid to more seasonal and humid conditions during the Middle Miocene Climatic Optimum. New climate models also support increased seasonality and moisture availability on the eastern flank of the Andes during the Middle Miocene Climatic Optimum, which we attribute to intensification of the South American Monsoon. We compare our results with published sequentially restored, regional cross-sections to explore linkages between the climatic shift and orogenic growth. A more seasonal climate should drive increased erosion, which in turn should drive the wedge into sub-critical state as predicted by critical taper theory.

The timing of deformation within and adjacent to the Helena salient of west-central Montana is poorly constrained relative to other segments of the Sevier fold-and-thrust belt. This study presents low-temperature thermochronology data from the Little Belt Mountains, a basement-cored Laramide uplift that is juxtaposed with the leading edge of the salient. We analyzed eight samples of Paleoproterozoic basement for apatite fission-track (AFT) and zircon (U-Th)/He (ZHe) thermochronology. Four samples yielded AFT ages ranging from ca. 80 Ma to 73 Ma and associated long, unimodal confined track lengths, indicating rapid cooling and exhumation of Little Belt Mountains basement during the Late Cretaceous. The other four samples are characterized by younger AFT ages (ca. 55 Ma), which suggest a combination of prolonged residence in the apatite partial annealing zone and postexhumation magmatic reheating. In total, 20 new ZHe dates range from ca. 236 Ma to 28 Ma and show a correlation between date and effective uranium. Forward model results for ZHe data are consistent with upper-crustal residence during the Proterozoic followed by Phanerozoic burial and rapid Late Cretaceous cooling. Cross sections across the Little Belt Mountains display the geometry of the Volcano Valley fault zone, an array of down-to-the-south Proterozoic normal faults that profoundly influenced the development of the Cordilleran thrust belt. Our new constraints from the Little Belt Mountains when integrated with published kinematic constraints from the Helena salient reveal significant out-of-sequence deformation in this portion of the thrust belt between ca. 80 Ma and 55 Ma. A kinematic model is proposed that involves Late Cretaceous (ca. 80 Ma) exploitation of rheologically incompetent units at the base of the Belt Supergroup within the Helena Embayment, facilitating early exhumation in the Little Belt Mountains. Our new data and synthesis are consistent with previous interpretations in which an inherited stratigraphic and structural architecture of Proterozoic ancestry was the predominant control on the development of the Helena salient during Cretaceous−early Eocene time.

Respiratory virus infections in humans are a significant global health concern, causing a wide range of diseases with substantial morbidity and mortality worldwide. This underscores the urgent need for effective interventions to reduce the ...Respiratory virus infections in humans cause a broad-spectrum of diseases that result in substantial morbidity and mortality annually worldwide. To reduce the global burden of respiratory viral diseases, preventative and therapeutic interventions that are ...

New regional mapping and two focused geological maps with two crustal-scale balanced cross-sections along the Dudh Kosi and Tama Kosi Rivers in the Okhaldhunga region reveal the structural architecture of the eastern Nepal Himalaya. Our detrital zircon U-Pb ages for 14 samples and igneous zircon U-Pb ages for four samples show that the Okhaldhunga window primarily exposes the Ramgarh thrust sheet, which is composed of Paleoproterozoic Lesser Himalayan metasedimentary and igneous rocks. Structurally, the Ramgarh thrust sheet lies in the footwall of the Main Central thrust and is underlain by the Lesser Himalayan duplex (LHD), a hinterland dipping bumpy-roofed duplex, comprising Paleo-Mesoproterozoic Lesser Himalayan rocks and upper Paleozoic Gondwana Sequence rocks. The frontal part of the LHD is exposed in the southern sector of the Okhaldhunga window, above a major footwall ramp on the Main Himalayan thrust. Neoproterozoic-Cambrian Greater Himalayan rocks in the hanging-wall of the Main Central thrust are exposed toward the south in the synformal Mahabharat Range and in the north in the Sagarmatha-Rolwaling region. Kinematic restorations for our two transects, combined with published chronometric data, indicate that most of the deformation has been accommodated by Lesser Himalayan rocks since Middle-Late Miocene. The two balanced cross-sections indicate minimum shortening of similar to 561 and 544 km. Comparison of these estimates with published data for rocks structurally below the South Tibetan detachment system in the Himalaya indicates that heterogeneous post-collisional crustal shortening has determined the current tectonic configuration of the region.

The McCoy Mountains Formation (McMF) in southern California-Arizona preserves an anomalously thick record of sedimentation during the Mesozoic at a critical time when western North America experienced contrasting tectonic events related to intracontinental rifting along the Mexican Border rift system and consolidation of the North American Cordilleran system. The spaciotemporal interactions among these events and the development of the McCoy basin challenge our understanding of the evolution of the southern extent of North America. At its type locality in the McCoy Mountains, the McMF consists of similar to 7 km of low-grade metasedimentary rocks, originally interpreted as meandering fluvial to alluvial-fan deposits. Uncertainty in the initial timing of sedimentation in the McCoy basin has resulted in multiple tectonic models. We measured similar to 7160 m of detailed stratigraphy and present new sedimentological and detrital zircon results showing that the McCoy basin was occupied by deep-water turbidite systems. These systems deposited an upward-coarsening succession of fine- to coarse-grained detritus during the Cretaceous (ca. 137-70 Ma). Provenance data indicate that the McCoy basin received sediment from Proterozoic basement rocks and metamorphosed Palaeozoic to early Mesozoic sedimentary units. These source rocks are equivalent to the stratigraphy found in the Grand Canyon and Colorado Plateau regions and were likely shed from the southward-advancing Maria fold-thrust belt and possibly the southern Sevier belt in southern Nevada and California. These results, combined with subsidence curves typical of foreland basins, favour deposition within a subaqueous flexural foreland basin system. The presence of a Cretaceous foreland basin this far southwest challenges previously proposed models and suggests that the contractional tectonic regime associated with the North American Cordillera extended into the southwestern most United States during the Early-Late Cretaceous.

The Manantiales basin contains >4 km of nonmarine sedimentary strata that accumulated at 31.75-32.5(degrees)S during construction of the High Andes. We report field and analytical data from the underexplored northern portion of this basin. The basin contains upper Eocene-middle Miocene strata that accumulated in back-bulge or distal foredeep through inner-wedge-top depozones of the Andean foreland basin as it migrated through this region. A revised accumulation history for the basin-filling Rio de los Patos and Chinches Formations supports a regional pattern of flexure in front of an east-vergent orogenic wedge. The former formation consists of eolian and localized fluviolacustrine deposits which accumulated between ca. 38 Ma and <= 34 Ma during thrust belt development in Chile. A subsequent <= 12 Myr hiatus may reflect passage of the flexural forebulge or cessation of subsidence during orogenic quiescence. The overlying Chinches Formation records a transition from the foredeep to wedge-top depozones. Foredeep deposits of east-flowing, meandering streams were incised prior to ca. 18 Ma, after which deposits of axial rivers, playas, and perennial lakes ponded in a depression behind orogenic topography to the east. After ca. 15 Ma, alluvial-fan deposits were syndepositionally deformed adjacent to growing thrust-belt structures along the western basin margin. Although the basin record supports a westward step in the locus of deformation during Early-Middle Miocene time, it conflicts with models involving west-vergence of the orogenic wedge. Rather, this pattern can be explained as out-of-sequence deformation alternating with wedge forward propagation, consistent with Coulomb wedge models incorporating syntectonic sedimentation.

Carbonate rocks are susceptible to diagenesis, and the correct identification of diagenetic features and stages are primary tasks in paleoelevation and paleoclimate studies using carbonate proxies. In this study, we apply three key parameters that include stable isotopes, clumped isotope temperatures, and U-Pb ages to identify different diagenetic stages, i.e., eogenesis, mesogenesis, and telogenesis. We then adopt these criteria to explore the diagenetic history of the middle-late Eocene lacustrine carbonates in the Gerze area of western central Tibet, which have yielded contrasting interpretations of diagenetic stages and paleoelevation estimates. Petrographic observations and electron microprobe element mapping permitted the identification of different diagenetic features. The Gerze carbonates (4GZ section) contain distinct phases of micrite and vein/vug-fill calcite (sparite) with different stable oxygen isotope values of -4 to -6 %o and -10 to -14 %o (VPDB), respectively. The micrites are dominantly dolomite in composition and yield clumped isotope temperatures of 40-50 degrees C, which are interpreted to be the result of dolomitization during shallow burial. In contrast, the vein/vug-fill calcites exhibit lower clumped isotope temperatures of 20-30 degrees C and U-Pb ages of 3.0-3.3 Ma, indicating a late-stage telogenetic origin after exhumation to near the Earth's surface. Our documentation of different carbonate diagenetic stages sheds light on existing paleoelevation interpretations. We conclude that existing evidence remains inconclusive as to the paleoelevation of the Gerze area basin floors during the middle-late Eocene.

The Sub-Andean retroarc region is a unique example of an active continentalscale retroarc foreland basin system. Heavily targeted for hydrocarbon exploration, the region hosts a large volume of subsurface data coupled to surface studies dedicated to refining its evolution in time and space. This paper presents a regional correlation of stratigraphic markers from seismic reflection and well logs across the Sub-Andean foothills at 23-21 degrees S in southern Bolivia and northern Argentina, which reveals the contrasting tectonics that preceded the foreland basin setting. Supported by published geochronological data and new zircon U-Pb maximum depositional ages, we describe the deposistratigraphy and discrete episodes of foreland basin subsidence and shortening. Based on interpreted stratigraphic breaks, we define the extent and stepwise evolution of this foreland basin, which was characterized by the progressive eastward migration of foreland basin depozones. Based on restored thickness profiles, we present flexural models of basin subsidence for the Sub-Andean foothills region. The modeling of discrete episodes of foreland basin subsidence refines the widely accepted bimodal elastic strength in the foreland basin at 21-23 degrees S, which is weaker in the western ranges (similar to 20 km effective elastic thickness) and stronger eastward (>40 km). Modeling results also reveal minimum values of subsidence rates (up to 1.2 mm/yr) in the sequential foredeep depozones and suggest that the modeled tectonic load migration-as constrained by the record of syntec tonic strata-probably increased over time through the incorporation of Sub-Andean rocks into the orogenic wedge.

Paleoelevation and paleoclimate reconstructions based on carbonate proxies rely on the preservation of syndepositional surface water isotopic signatures. This study investigates the reliability of fine-grained carbonates (micrites) in recording well-preserved isotopic composition. Utilizing a suite of research tools, including petrography, X-ray diffraction mineralogy, stable isotopes, clumped isotope temperatures, isotope mixing, solid-state bond reordering modeling, and trace element concentrations, we examine the diagenetic history of late Oligocene micritic carbonates from the Nima Basin in central Tibet. Our findings reveal that the lacustrine carbonates at deposition were micritic and calcite-dominated. However, they underwent partial dolomitization through cryptic recrystallization during shallow burial at temperatures of similar to 34-40 degrees C, likely influenced by groundwaters with abundant Mg2+ and trace elements distinct from surface waters. Subsequently, during the further burial at temperatures of similar to 120-130 degrees C, vein calcites precipitated from thermal fluids. Concurrently, the calcite component of fluid-adjacent micrites underwent open-system recrystallization, recording temperatures of 100-130 degrees C, while the associated dolomite component remained minimally altered due to its higher resistance to dissolution. In contrast, micritic calcites unaffected by thermal fluids experienced partial solid-state bond reordering that elevated clumped isotope temperatures to 50-60 degrees C. This study underscores the complex diagenetic histories that micrites can undergo, emphasizing the need for caution when interpreting carbonate stable oxygen isotopes in paleoclimate and paleoelevation studies, especially in tectonically active regions. Finally, our analysis infers that the stable oxygen isotopic values of the calcitic soil carbonates in the Nima Basin are well-preserved and reflect moderately high paleoelevations of similar to 3.3 km at 26-25 Ma. This suggests a >1 km elevation gain during the Neogene, highlighting subsurface geodynamic processes as additional drivers of surface uplift in central Tibet.

Informal verbal interaction is the core matrix for human social life. A mechanism for coordinating this basic mode of interaction is a system of turn-taking that regulates who is to speak and when. Yet relatively little is known about how this system ...