Proximal Source Research Articles

Hysteresis analysis reveals dissolved carbon concentration – discharge relationships during and between storm events

The dissolved carbon concentration, which is responsible for aquatic ecosystem productivity and water quality, is tightly coupled with hydrological processes. Excess dissolved carbon may exacerbate eutrophication and hypoxia in aquatic ecosystems and lead to deterioration of water quality. Storm events dominate the dynamics of dissolved carbon concentrations, and this nonlinear behavior exhibits significant time scale dependence. Here, we identified inter- and intra-event variability in the dissolved carbon concentration–discharge (C–Q) relationship in an agriculture-intensive catchment. The driving factors of C–Q hysteresis patterns for dissolved inorganic carbon (DIC) and organic carbon (DOC) were quantified by redundancy analysis combined with hierarchical partitioning. At the inter-event scale, DIC exhibited mainly clockwise hysteresis, indicating an exhaustible, proximal source (e.g., groundwater). However, DOC hysteresis was generally counter-clockwise, indicating distal and plentiful sources (e.g., soil water) in the agricultural catchment. Hierarchical partitioning showed that total rainfall, peak discharge and flood intensity explained 28.38% of the total variation in C–Q hysteresis for DIC and 39.87% for DOC at the inter-event scale. At the intra-event scale, time series analysis of dissolved carbon concentration and discharge indicated the interconversion of supply limitation to transport limitation, which depends on the activation of the specific DIC or DOC source zones. These findings provide significant insights into understanding the dynamics of dissolved carbon during storm periods and are important for targeted watershed management practices aimed at reducing carbon loading to surface waters.

Quantifying international and interstate contributions to primary ambient PM2.5 and PM10 in a complex metropolitan atmosphere

We quantify the contributions of long-range and regionally transported aerosols to ambient primary PM2.5 and PM10 in a representative United States industrialized/urban atmosphere via detailed elemental analysis and chemical mass balance (CMB) modeling after identifying their presence using a variety of publicly available satellite data/information, software products, and synoptic-scale aerosol models. A year-long study in Houston, Texas identified North African dust as the principal long-range global source of primary particulate matter (PM). CMB estimated transatlantic dust from the Sahara-Sahel region to be dominant in the summer months contributing an average of 3.5 μg m−3 to PM2.5 and 7.9 μg m−3 to PM10 during May–August, i.e., the active Saharan dust season. Biomass burning was the chief source of regionally transported PM impacting air quality on different occasions throughout the year depending on the fire location. Four major biomass combustion events affecting air quality in Texas were calculated to contribute an average of 1.3 μg m−3 to PM2.5 and 1.4 μg m−3 to PM10 in corresponding samples whose origins were tracked to Canada, southeastern states of USA, and Central America using fire maps, HYSPLIT back trajectories, and the Navy Aerosol Analysis and Prediction System global aerosol model. Elemental concentrations and signature ratios revealed significant mixing of potassium, rare earth metals, and vanadium from proximal and distal crustal (natural) sources with anthropogenically emitted PM. This demonstrates the need to isolate the non-mineral components of these metals to employ them as tracers for primary PM emitted by biomass burning, petroleum refineries, and oil combustion. Transboundary contributions to primary PM2.5 were 1.5 μg m−3 and 3.1 μg m−3 to PM10 adding 16% to annual average mass concentration of both size fractions demonstrating that local sources were primarily responsible for ambient air quality with non-trivial contributions from international and interstate sources. Rigorously identifying and quantifying aerosol sources assists in improving air quality management policies designed to protect public health and comply with ever-decreasing federal PM standards that allow state agencies to exclude contributions that are not reasonably controllable or preventable from regulatory decisions and actions.

Tectonic and climatic controls on sediment transport to the Southeast Indian Ocean during the Eocene: New insights from IODP Site U1514

The Eocene was a critical period of global plate reorganization and it also saw the Earth's climate transition from the warmhouse state to the coolhouse state. Reconstructing the Eocene sedimentary history in the climate-sensitive Southern Ocean is important for understanding paleoenvironmental changes in response to the accelerated Australia/Antarctica separation and global cooling throughout the middle and late Eocene. Here, we present the first detailed multiproxy record of a continuous sequence from International Ocean Discovery Program (IODP) Site U1514 in the Mentelle Basin off southwestern Australia. Our aim is to reconstruct the sediment provenances and paleoenvironmental evolution in response to the abovementioned climatic and tectonic changes in the mid-high southern latitudes during the Eocene. Provenance analyses based on Sr-Nd isotopes, trace elements, and clay mineral assemblages suggest that Eocene sediments at Site U1514 predominantly originated from the southwestern Australian continent and the Naturaliste Plateau. Sediment provenance variations during the middle Eocene indicate that the onset of fast separation between Australia and Antarctica at 43 Ma caused an increased supply of volcanic materials from the Naturaliste Plateau between 43 and 38 Ma. Terrigenous inputs to the Mentelle Basin during the middle Eocene were primarily controlled by paleoclimate changes rather than tectonic processes because coeval clay mineralogical changes (higher kaolinite/smectite ratio and MARkaolinite) indicate a period of stronger physical erosion and chemical weathering on the western Australian continent that resulted in increased terrigenous materials delivered to the Mentelle Basin. Our results reveal a 5 Myr-long (43–38 Ma) warming reversal in the southern mid-high latitudes, providing an exception to the generally short-lived (10–100 kyr-long) hyperthermals that interrupted the long-term global cooling throughout the middle to late Eocene. As for the late Eocene (38–37 Ma), tectonic processes related to the sudden acceleration in seafloor spreading in the Tasman Sea led to the exposure of shallower areas, resulting in rapid detritus accumulation at the study site. During the late Eocene (37–34 Ma), major sediment provenance shifted from distal source areas (e.g., the Yilgarn Craton) to relatively proximal sources (e.g., the Leeuwin Block and Perth Basin). We interpret that the regional uplift in southwestern Australia and coeval climate cooling resulted in the diversion and inactivation of large drainage systems, thus blocking the transportation of sediment from distant regions.

Mechanism of Capacitive Coupling of Proximal Electromagnetic Sources With Biological Bodies.

This study investigates the absorption of the induced E-field in homogeneous biological tissue exposed to highly localized field sources in proximity of the body, such as the charged tips of antennas, where E-field coupling dominates. These conditions are relevant for compliance testing of modern mobile phones where exposure is evaluated at small separation between radiators and the body. We derive an approximation that characterizes the decay of the induced E-field in the tissue as a function of distance. The absorption is quantified in terms of the local specific absorption rate (SAR) at the tissue surface as a function of the charge at the antenna tip. The approximation is based on the analytical evaluation of the E-fields of a charged disk under quasi-static conditions. We validate this approximation using full-wave simulations of dipoles. We demonstrate that the coupling mechanism of the E-field is dominated by the perpendicular field component and that wave propagation need not be considered for the characterization of the exposure. The surface SAR decreases approximately with the fourth power of the distance and with the square of the ratio of the permittivities of the tissue and free-space. The approximation predicts the induced maximum E-field with an accuracy of better than 1.5 dB. © 2022 Bioelectromagnetics Society.

Source areas of the Eastern Ebro Valley loess (NE Iberian Peninsula): Heavy mineral composition as a provenance indicator

AbstractLoess deposits of the Eastern Ebro Valley (NE Iberian Peninsula) occupy an area of ~2000 km2 mostly on the east of the Ebro depression and locally in the Móra Basin. We studied 38 samples of loess and 47 samples of their possible source areas, in order to determine the location of the origin of the loess materials, based on their particle size distribution and composition of heavy minerals. Our results clearly differentiate two depositional loess basins disconnected by the reliefs of the Pre‐Coastal Range with different mineralogical signatures: the Ebro Basin and the Móra Basin. The most relevant variables to discern source areas were the percentage of heavy minerals, the concentrations of zircon, staurolite, rutile and inosilicates, and the presence of gypsum. In the Ebro Basin, the largest set of loess deposits is located around a depocenter in the Batea region and along several lateral areas, with materials that come from the central alluvial plain of the Middle Ebro River (25 to >100 km travel distance), in addition to deflated materials from Miocene interfluvial substrates. On the other hand, loess deposits of the Móra Basin come from more proximal source areas (<15 km), originating from the alluvial materials of the Lower Ebro River that contain the contributions of its tributaries, the Cinca and Segre rivers. Taking into account the homogeneity in the mineralogical composition of complex loess sequences, we deduced a general WNW–ESE wind direction, which would have remained constant over the last two cold periods (MIS‐2 and MIS‐6). Along this axis, the Pàndols–Cavalls Range, with a height difference of 200–350 m, acted as a wind barrier separating the loess of Ebro Basin from the loess of Móra Basin.

Distribution Pattern Analysis of Cortical Brain Infarcts on Diffusion-Weighted Magnetic Resonance Imaging: A Hypothesis-Generating Approach to the Burden of Silent Embolic Stroke.

Background In patients with covert cerebrovascular disease or proximal source of embolism, embolic silent brain infarction may precede major stroke events. Therefore, characterization of particularly cortical silent brain infarction is essential for identifying affected patients and commencing adequate secondary prevention. This study aimed to investigate differences in the distribution pattern of cortical ischemic stroke lesions to assess potential predilection sites of cortical silent brain infarction. Methods and Results We prospectively included all consecutive patients with stroke presenting from January 1 to December 31, 2018. Diffusion-weighted imaging lesions were used to generate voxel-based lesion maps and assigned to atlas-based cortical regions of interest in middle cerebral artery territories. Each region-of-interest lesion frequency was related to the respective region-of-interest volume to identify frequently affected and underrepresented cerebral cortex areas. Diffusion-weighted imaging data for voxel-based lesion maps were available in 334 out of 633 patients. Primary analysis revealed that small- (<0.24 cc) and medium-sized (0.24-2640 cc) lesions distributed predominantly along regions associated with sensorimotor or language function. Detailed analysis within middle cerebral artery territories showed an approximated frequency of missed cortical stroke lesions of up to 67% in the right and 69% in the left hemisphere. In particular, the frontal, temporal, and occipital cortices were underrepresented. Larger lesion size and areas associated with higher cortical function led to hospital admission. Conclusions Cortical brain infarcts in hospitalized patients are not dispersed equally but are predominantly located in brain structures associated with motor control and sensory and language function. Matching underrepresented cerebral cortex regions to symptoms not yet associated with stroke warrants further exploration.

Peers and teachers as the best source of social support for school engagement for both advantaged and priority education area students.

Promoting student’s school engagement is a major goal in our society. The literature has shown that students’ proximal sources of social support can play a fundamental role in facilitating this engagement. The purpose of this study was (1) to compare perceived support from four sources (mother, father, teacher, and peers) as a function of two different middle-school student backgrounds, a priority education area and a privileged area; (2) and (3) to examine the contribution of these main sources of social support, either directly or indirectly (through sense of school belonging) to school engagement; and (4) to test whether perceived social support is more strongly related to school engagement, directly or indirectly, among students from priority education school compared to students from the advantaged area. In all, 623 middle-school students (aged 11–16) from either a privileged or priority education area participated in this study. The results showed that the mother was perceived as providing more support, followed by the father, the teachers, and the peers. Students from the priority education area perceived more support from their teachers than their counterparts from the more privileged area did. A path analysis showed that each source of social support, except for maternal support, contributed to school engagement. Peers and teachers emerged as the best source of support for school engagement, having significant direct effects among students from the priority education area and both direct and indirect (through the sense of school belonging) effects among students from the advantaged area. Peer support also appears to have a double-edged effect on school engagement among students in the priority education area. This study contributes to enlightening the phenomenon of school engagement in adolescence by clarifying the role of social support and the related mediating process. Being perceived as an important source of social support by students is not enough to contribute to their sense of school belonging and school engagement.

Transportation of sediments by floating processes from southern Europe to the coastal regions of eastern Libya: Pumice rock fragments from at Tariyah and Qasr Libya coasts1

Abstract&#x0D; Fragments of pumice of various sizes and roundness were found mixed with recent coastal sediments of calcareous sand, calcareous granules, and shells in At Tariyah coast southwest of Benghazi, and in the coastal area of Qasr-Libya, Al Jabal Al Akhdar, northeastern Libya. The source area for the pumice fragments appears to be the active volcanic regions of eastern and southern Sicily; Etna volcano and submarine volcano known as the CampiFlegrei del Mar di Sicilia respectively. &#x0D; The pumice must have traveled a distance of at least 1000km across the Mediterranean Sea as a floating load. &#x0D; The recent coastal sediments of the Al Jabal Al Akhdar area are derived mainly from two different sources; a southern proximal source consisting of a well-exposed sequence of Tertiary carbonate rocks that produced well-sorted sand-size fragments and a northern distal source that produced cobble-size fragments of pumice. &#x0D; The mechanism of transporting sediments by floating as a floating load, from one sedimentary basin to another is completely different from the other well-known and documented methods of bedload and suspended load. Floating fragments can be transported for long distances and finally deposited without appreciable changes in size, roundness, shape, or sorting. Pumice deposited on the eastern coast of Libya indicates that long-distance transport produces minimal or negligible changes in the textural parameters of floating load components.

Mass wasting along the Cascadia subduction zone: Implications for abyssal turbidite sources and the earthquake record

The only submarine records of large (>Mw7) prehistoric earthquakes along the Cascadia subduction zone are derived from sequences of deep sea turbidites interpreted to represent synchronous, shaking-induced failures along the continental slope. However, the spatial correlation of these deposits along the margin is complicated and the chronological constraints involve significant uncertainties, raising questions about how these deposits were generated. Here we present the most comprehensive spatial database of seafloor failure scarps across the Cascadia margin to date, with more than 8700 features mapped. We observe pervasive mass wasting of the steep lower slope along the ∼800 km length of the margin. This portion of the margin is heavily deformed, uplifted and oversteepened, such that it may be optimally preconditioned to fail during intense shaking events. Our results suggest disintegration of the steep lower slope is likely the primary source of turbidity flows triggered by earthquake shaking in Cascadia. This more proximal source for seismoturbidite generation may be the principal process along subduction margins with steep lower slope topography and may explain why seismoturbidites are found in areas containing few submarine canyons. Furthermore, the extensive mass wasting present on the steep lower slope of central Cascadia, a critical 250 km long section where no records currently exist, suggests additional turbidite records may be found along this portion of the margin by selecting optimal sample sites based on failure patterns. The strong clustering of seafloor failures along the lower slope also suggests the most earthquake intense shaking may be spatially restricted to a narrow zone along the deformation front, which could have important implications for hazard predictions across the region.

The Evolution of Permian Source-to-Sink Systems and Tectonics Implications in the NW Junggar Basin, China: Evidence from Detrital Zircon Geochronology

The basin type of the Junggar Basin changed during the Permian, but the time constraint of the tectonic evolution remains unclear. Besides, the fan deltas developed in the Permian in the Mahu Sag in the northwestern of the oil-rich basin. However, the provenances of the sedimentary systems remain unclear. Based on petrology and detrital zircon U-Pb ages, this study investigates the source-to-sink systems evolution and tectonics implications. Abundant lithic clasts in sandstones with low compositional and textural maturity imply proximal sources. The dating results showed a dominant peak (310–330 Ma) and a secondary peak (400–440 Ma) in the northern Mahu Sag, only one peak at 295–325 Ma in the central Mahu Sag, several peaks at 270–350 Ma in the southern Mahu Sag, and multiple peaks at 370–450 Ma in the Zhongguai Uplift. Thus, the north-western Junggar Basin was divided into four major source-to-sink systems, with adjacent central West Junggar as the main provenance and northern and southern West Junggar as the secondary provenance. The proportion of sediment supply from the southern and northern West Junggar is higher during the Middle-Late Permian. It suggests that the source-to-sink systems show inheritance and evolve from a single provenance into a complex provenance, indicating the uplift of West Junggar. The tectonic inversion may occur early in the Middle Permian and the response to tectonic activity is stronger in the southern West Junggar than in the northern West Junggar.

A “Local First” Approach to Glacigenic Sediment Provenance Demonstrated Using U-Pb Detrital Zircon Geochronology of the Permo-Carboniferous Wynyard Formation, Tasmanian Basin

We propose that a “local first” approach should be applied to the interpretation of provenance indicators in glacigenic sediments of all depositional ages, especially where the glacier flow path is poorly constrained and the records of potential source lithologies are incomplete. Provenance proxies, specifically U-Pb detrital zircon geochronology, of glacigenic sediments are commonly used to infer the size and distribution of past ice centers, which are in turn used to inform ancient climate reconstructions. Interpretations of these proxies often assume that similar provenance signals between glacigenic units of the same depositional age are evidence that they were deposited by the same glacier, even when those units are, not infrequently, separated by thousands of kilometers. Though glaciers are capable of transporting sediment great distances, this assumption is problematic as it does not acknowledge observations from the geologic records of Pleistocene ice sheets that show provenance proxies in glacial sediments are most likely to reflect proximal (within 100 km) sediment sources located along a specific flow path. In a “local first” approach, provenance indicators are first compared to local source lithologies. If the indicator cannot be attributed to proximal sources, only then should progressively more distal sources be investigated. Applying a local first approach to sediment provenance in ancient glacial systems may result in significant revisions to paleo ice sheet reconstructions. The effectiveness of the local first approach is demonstrated here by comparing new U-Pb detrital zircon dates from the Permo-Carboniferous glacigenic Wynyard Fm with progressively distal source lithologies along the glacier’s inferred flow path. The Wynyard Fm and source lithologies were compared using an inverse Monte-Carlo unmixing model (DZMix). All measured Wynyard Fm detrital zircon dates can be attributed to zircon sources within 33 km of the sample location along the glacier’s flow path. This interpretation of a proximal detrital zircon provenance does not conflict with the popular interpretation made from sedimentological observations that the Wynyard Fm was deposited by a large, temperate outlet glacier or ice stream that flowed south-to-north across western Tasmania. Overall, a local first approach to glacial sediment provenance, though more challenging than direct comparisons between glacigenic sedimentary deposits, has the potential to elucidate the complex histories and flow paths of glacial sedimentary systems of all depositional ages.

A case study application of machine-learning for the detection of greenhouse gas emission sources

Conclusively linking local, episodic enhancements in greenhouse gas concentrations to a specific emission source can be challenging, particularly when faced with multiple proximal sources of emissions and variable meteorology, and in the absence of co-emitted tracer gases. This study demonstrates and evaluates the efficacy of using machine-learning tools to detect episodic emissions of methane (CH4) from a shale gas extraction facility in Lancashire (United Kingdom). Two machine-learning tools (rmweather and Prophet) were trained using a two-year climatological baseline dataset collected prior to gas extraction operations at the facility. The baseline dataset consisted of high-precision trace gas concentrations and meteorological data, sampled at 1 Hz continuously between 2016 and 2019. The models showed good overall predictive capacity for baseline CH4 concentrations, with R2 values of 0.85 and 0.76 under optimised training conditions for rmweather and Prophet, respectively. CH4 concentrations were then forecast for an 18-month period from the onset of operations at the shale gas facility (in 2018). Forecast values were compared with true measurements to detect anomalous deviations that may indicate the presence of new emission events associated with the operational facility. Both models successfully detected two periods in which CH4 emissions were known to have occurred (December 2018 and January 2019) via anomalous deviations between modelled and measured concentrations. This work demonstrates the application of machine-learning models for the detection of CH4 emission events from newly built industrial sources, when used in combination with real-time atmospheric monitoring and a baseline dataset collected prior to installation.

Clinical and radiographic phenotypes of patients with multifocal subcortical versus cortical cerebral infarcts

Background and purposeInfarct topology is a key determinant in classification of a stroke as potentially embolic, with cortical and multifocal lesions being presumed embolic. Whether isolated subcortical multifocal infarcts are likely embolic has not been well studied. MethodsA prospective, single-center cohort study of consecutive patients with acute multifocal strokes confirmed on diffusion-weighting imaging (DWI) was queried, and patients compared according to the presence of isolated subcortical infarct topology versus cortical ± subcortical topology. Descriptive statistics and multivariable logistic regression were used to determine independent predictors of cryptogenic, subcortical infarcts. ResultsOf 1739 patients screened, 743 had complete diagnostic testing with DWI evidence of acute infarction, 183 (24.6%) of whom had a multifocal stroke pattern. Isolated subcortical involvement was disproportionate among patients with ESUS (64.9%) when compared to patients with cardioembolic (24.3%) or large vessel disease (10.8%, p<0.01). Following multivariable adjustment, independent predictors of isolated subcortical multifocal infarction were milder strokes (OR 0.94, 95%CI 0.89-0.98) and higher grade Fazekas score (OR 2.32, 95%CI 1.02-5.29), while cardioembolism (OR 0.30, 95%CI 0.08-1.13) and large vessel disease (OR 0.27, 95%CI 0.08-0.91) remained inversely associated (as compared to ESUS). ConclusionsThese data suggest that multifocal subcortical infarctions are less likely to have an associated proximal embolic source than multifocal infarctions with cortical involvement. The strong association with chronic microvascular disease suggests this topology is more consistent with acute-on-chronic microvascular injury rather than an occult embolic source.

The economics of sediment quality on barrier shoreline restoration

This paper depicts a simulation-based assessment of sediment quality on the performance of dedicated dredging projects for barrier island restoration in coastal Louisiana, USA. The research involved the development and integration of two sub-models. In the first, geomorphic modeling was used to simulate sediment transport dynamics within a proxy barrier island template over a 50-year trajectory. The template was assumed to be nourished with one of two sources of dredged material: nearshore (NS) sediments of lower quality (smaller grain diameter, higher organic fines); or higher quality sediments from distal sources located on the Outer Continental Shelf (OCS). In the second model, agency project records and commercial bids were used to estimate project construction costs as a function of dredge material quantity, transport distance, and project target elevation. These sub-models were coupled within a net present value framework from which average annual break-even values for ecosystem services (EBEV) were derived as an efficiency metric for comparing the economic performance of NS- and OCS-sourced projects. Results indicate that in some cases, the physical resiliency afforded by even small increases in sand diameter (+4 μm d50) can translate to greater long-term economic viability (lower EBEV) for OCS-sourced sediment transported over longer distances. Moreover, projects constructed with much higher diameter OCS sediment (+44 μm d50) with low fines and transported over relatively long distances (200 μm, 5% fines, 15–20 miles) were found to be more cost-effective than all comparably-sized projects constructed with lower quality NS sediments obtained from proximal sources (156 μm, 20% fines, 3–5 miles). For some comparisons, this quality advantage yielded a lower EBEV for OCS-sourced projects with transport distances exceeding 30 miles. Under storm-punctuated simulations, these quality advantages were more pronounced, with greater physical and economic implications for earlier (Y5) versus later (Y20) occurring storms. Budgeting for dedicated dredging projects has traditionally centered on the value of sediment as a commodity, with a focus on material placement cost. The findings of this study, however, indicate that a more comprehensive accounting of sediment quality and performance is required to maximize the economic efficiency of coastal restoration spending.

Anthropogenic land use and urbanization alter the dynamics and increase the export of dissolved carbon in an urbanized river system

Greenhouse gas emissions from urban rivers play a crucial role in global carbon (C) cycling, this is tightly linked to dissolved C in rivers but research gaps remain. The effects of urbanization and anthropogenic land-use change on riverine dissolved carbon dynamics were investigated in a temperate river, the River Kelvin in UK. The river was constantly a source of methane (CH4) and carbon dioxide (CO2) to the atmosphere (excess concentration of CH4 ranged from 13 to 4441 nM, and excess concentration of CO2 ranged from 2.6 to 230.6 μM), and dissolved C concentrations show significant spatiotemporal variations (p < 0.05), reflecting a variety of proximal sources and controls. For example, the concentration variation of dissolved CH4 and dissolved CO2 were heavily controlled by the proximity of coal mine infrastructure in the tributary near the river head (~ 2 km) but were more likely controlled by adjacent landfills in the midstream section of the rivers main channel. Concentration and isotopic evidence revealed an important anthropogenic control on the riverine export of CO2 and dissolved organic carbon (DOC). However, dissolved inorganic carbon (DIC) input via groundwater at the catchment scale primarily controlled the dynamics of riverine DIC. Furthermore, the positive relationship between the isotopic composition of DIC and CO2 (r = 0.79, p < 0.01) indicates the DIC pool was at times also significantly influenced by soil respiratory CO2. Both DIC and DOC showed a weak but significant correlation with the proportion of urban/suburban land use, suggesting increased dissolved C export resulting from urbanization. This research elucidates a series of potentially key effects anthropogenic activities and land-use practices can have on riverine C dynamics and highlights the need for future consideration of the direct effects urbanization has on riverine C dynamics.

Source-to-sink evolution of syn-rift alkaline lake sediments in the Lower Permian Fengcheng Formation, Junggar Basin, NW China: Evidence from petrology, detrital zircon geochronology and geochemistry

• Chemical weathering intensity increased upwards in the ∼ 280 Ma Fengcheng Formation. • Detrital material of the FC Formation was supplied by the West Junggar, due to active normal faults. • Syn-rift sediments were deposited in an alkaline lake under arid climatic conditions. Source-to-sink evolution of intracontinental rift basins is an effective tool to evaluate syn -rifting tectonic processes and sediment dispersal. Provenance analysis, using petrological and geochemical analysis and detrital zircons U-Pb dating of the Lower Permian Fengcheng Formation, provides new insights into the provenance of alkaline lake deposits in the Mahu sag, Junggar Basin. Volcanic detritus and detrital feldspar grains are abundant, indicative of proximal sources. The rare earth and trace element characteristics of three sandstone samples are consistent with a dominant source from the Carboniferous – early Permian mafic and felsic rocks in West Junggar. Sandstone geochemistry suggests that chemical weathering intensity increased upwards, probably in response to reduced aridity. The detrital zircon U-Pb age patterns show a prominent Carboniferous peak (340–300 Ma), minor early Permian (∼280 Ma) and Silurian peaks (440–420 Ma). Quantitative unmixing modelling suggests that most detrital zircons were derived laterally from the Central West Junggar (CWJ), and a few zircons were derived axially from the Zharma-Saur and Boshchekul-Chingiz arcs in Northern and Southern West Junggar. The lateral source was more important in the Middle Member than in the Lower Member of the Fengcheng Formation. The average age of the youngest five detrital zircons and the low weathering indices indicate that the maximum slip of the bounding normal fault occurred at 284–?279 Ma. Seismic and hydrothermal activity caused by the normal fault displacement, as well as the increase in the supply of volcanic composition from the lateral CWJ, played an important role in the alkaline lake deposition.

Long-term analysis of cryoseismic events and associated ground thermal stress in Adventdalen, Svalbard

Abstract. The small-aperture Spitsbergen seismic array (SPITS) has been in continuous operation at Janssonhaugen for decades. The high-Arctic location in the Svalbard archipelago makes SPITS an ideal laboratory for the study of cryoseisms, a nontectonic class of seismic events caused by freeze processes in ice, ice–soil, and ice–rock materials. We extracted a catalog of &gt; 100 000 events from the nearly continuous observation period between 2004 and 2021, characterized by short-duration ground shaking of just a few seconds. This catalog contains two main subclasses where one subclass is related to underground coal-mining activities and the other is inferred to be dominated by frost quakes resulting from thermal-contraction cracking of ice wedges and crack-filling vein ice. This inference is supported by the correspondence between peaks in observed seismicity with peaks in modeled ground thermal stress, based on a Maxwellian thermo-viscoelastic model constrained by borehole observations of ground temperature. The inferred frost quakes appear to be dominated by surface wave energy and SPITS proximal source positions, with three main areas that are associated with dynamic geomorphological features, i.e., erosional scarps and a frozen-debris/solifluction lobe. Seismic stations providing year-round, high-temporal-resolution measurements of ground motion may be highly complementary to satellite remote sensing methods, such as InSAR (interferometric synthetic aperture radar), for studying the dynamics of periglacial environments. The long-term observational record presented in this study, containing tens of thousands of cryoseismic events, in combination with a detailed record of borehole ground temperature observations, provides a unique insight into the spatiotemporal patterns of cryoseisms. The observed patterns may guide the development of models that can be used to understand future changes to cryoseismicity based on projected temperatures.

Protracted (>60 Myrs) thermal evolution of a Neoproterozoic metasedimentary sequence from eastern Borborema Province (NE Brazil): Thermal and rheological implications for orogenic development

The thermal evolution of orogenic belts is quite varied. While some show rapid cooling, others record high temperatures for tens of millions of years. Here, we report the latter situation based on U-Pb zircon and monazite dating of paragneiss and micaschist from the Surubim Complex (eastern Borborema Province, NE Brazil). The Borborema Province and its African counterparts (Cameroon belt and Nigerian Shield) formed during amalgamation of West Gondwana in the Late Neoproterozoic (Brasiliano/Pan-African Orogeny). The location of the Surubim Complex in the central core of this large orogenic system offers the opportunity to study tectonic processes at work in the inner regions of ancient orogens. Basement-involved thick-skinned tectonics, regional low-angle foliation related to NW-directed thrusting, transcurrent shear zones and intrusion of granitic plutons characterize the Brasiliano Orogeny in the study area. Zircon data indicate provenance of the Surubim Complex mainly from proximal sources, predominantly 2.2–2.0 Ga-old basement rocks (including an orthogneiss here dated at 2132 ± 11 Ma), and from Neoproterozoic extension-related granitoids. The ages of the youngest detrital zircon grains range from 690 to 650 Ma. The weighted mean age (647 ± 4 Ma) of low Th/U zircon overgrowths in one sample is tentatively interpreted as dating syn-extensional metamorphism given the small age difference to the youngest detrital zircon population. A time lag of c. 17 Myrs, between 647 Ma and 630 Ma, suggests a temperature drop due to contractional deformation. The ages of the oldest magmatic grains from a leucosome sample and of monazite grains from a paragneiss sample, together with data from the literature, show that temperatures high enough to promote local anatexis during development of the regional low-angle foliation were reached around 630 Ma. Afterwards, as indicated by zircon and monazite growth and/or recrystallization, temperatures remained relatively elevated until the transition to the transcurrent regime, at c. 590 Ma, and persisted so up to c. 563 Ma. The results outline a protracted thermal history spanning more than 60 Myrs. This evolution is comparable to the tectonothermal evolution of long-lived hot orogens, where persistence of high temperature conditions for a long time has been related to the formation of orogenic plateaus.

Trade, production, and cultural integration at Cerro de Coamiles, Nayarit

During the Early/Middle Postclassic (AD 900-1350), the Aztatlan Tradition spread throughout Western Mexico and grew to be one of the most influential groups in the region. The cultural core of this tradition was centered on the coastal plain of Nayarit with numerous major population centers taking part in expansive trade networks. One such major Aztatlán site is Coamiles, excavated from 2005 to 2010 by the Instituto Nacional de Antropología e Historía (INAH). From these excavations, we here present the results of ceramic and obsidian analyses as well as discussions of site architecture. These results demonstrate the widespread importation of obsidian from the Jalisco highlands as well as simultaneous local production of lithic tools from more proximal sources. In contrast, ceramic analyses illustrate a ceramic industry that appears largely reliant upon local production with little, if any, ceramic trade. Finally, the architecture of the ceremonial center suggests an integration into broader cosmological belief systems that are still maintained today with modern indigenous populations. Overall, Coamiles was a paragon of Aztatlán culture. We can look to Coamiles and see similar attributes as we find throughout the entire coastal plain during the Postclassic. In this way, Coamiles is an ideal case study for understanding this prolific tradition.

Clinical implications of the distinct anatomy and innervation of the long head biceps tendon.

The proximal long head of the biceps tendon (LHBT) has been recognized as a well-known cause of anterior shoulder pain. Previous studies have identified a heterogeneous distribution of nerve fibers in the tendon, with a higher abundance of fibers in the proximal and distal thirds of the tendon. This suggests that the proximal portion of the long head biceps tendon may have a different source of innervation than the distal portion. The purpose of this study was to review the innervation of the superior shoulder and identify the proximal source of sensory innervation of the LHBT. The relevant hypothesis was that the suprascapular nerve (SSN) was the proximal source of sensory innervation to the LHBT. Gross and microdissection of eight fresh human cadaver shoulders were performed, with a focus on the distal articular branches of suprascapular nerve (SSN). Utilizing 3.5× magnification loupes, the medial subacromial branch (MSAb), lateral subacromial branch (LSAb), and posterior glenohumeral branch (PGHb) were identified and followed distally to their terminal branches. In all specimens, terminal branches of the lateral subacromial branch supplied the proximal LHBT and the superior labrum. Terminal branches of the posterior glenohumeral branch supplied the posterosuperior labrum and, to a lesser extent, the labral attachment of the LHBT. These findings confirm branches of the suprascapular nerve as the proximal source of sensory innervation to the LHBT. Identification of the suprascapular nerve as a source of proximal innervation of the LHBT may influence clinical decisions related to nonsurgical and surgical intervention, nerve blocks, and nerve ablation procedures.