Cenozoic tectono-geomorphological growth of the SW Chinese Tian Shan: insight from AFT and detrital zircon U-Pb data

International audienceAs a unique example of the intracontinental mountain building, the Cenozoic deformation of the Tian Shan has been widely studied. The onset of Cenozoic exhumation of the SW Chinese Tian Shan was constrained at the Oligocene-Miocene boundary. However, the Cenozoic tectono-geomorphological growth process of the SW Chinese Tian Shan and adjacent piedmont basins remains a challenge. In this study, we carried out the geological mapping of satellite images and field investigations together with the apatite fission track (AFT) and detrital zircon U-Pb analyses to get further understanding of the Cenozoic tectonic deformation and geomorphological growth of the SW Chinese Tian Shan. Our results indicate that the exhumation of Maidan fault or topography growing of the Kokshaal Range commenced in the late Eocene ∼ Oligocene (35 - 25 Ma). Then, the structural deformation migrated southward to the Muziduke fault and the Atushi Basin Thrust (ABT) at ∼ 15 Ma. The growth strata of 6 - 3 Ma on the south flank of Keketamu Anticline imply that tectonic deformation propagates further basinward. Furthermore, the uplift of the Kokshaal Range also strongly affected the evolution of piedmont basins. The results suggest that the Atushi Basin was still likely linked to the Aksai Basin during the early Miocene. They were separated into two independent basins since ca. 13.7 - 10.5 Ma, as a response to the rapid uplift of the Kokshaal Range. Finally, we infer that the southeastern part of dextral Talas-Fergana fault (TFF) is likely transferred to the NEE-trending thrust faults of the SW Chinese Tian Shan since ∼ 15 Ma

Unbalanced sediment budgets in the catchment-alluvial fan system of the Kuitun River (northern Tian Shan, China): Implications for mass-balance estimates, denudation and sedimentation rates in orogenic systems

International audienceMass balances are often used to calculate sediment fluxes in foreland basins and denudation rates in adjacent mountain ranges on intermediate to long timescales (from a few tens of thousand to a million years). Here, we study the simple Quaternary catchment-alluvial fan system of the Kuitun River, in northern Tian Shan, to discuss some ideas about sediment storage, release, and bypass in relatively short (100 km long) sediment routing systems. This study shows that the Kuitun catchment and piedmont areas clearly present evidence of a significant and temporary storage of sediments during the Pleistocene. These sediments were then excavated and delivered farther into the foreland basin during the Holocene. The difference between the volumes of materials released from the catchment and piedmont areas (5.5 ± 1.7 km3) and the volume stored in a contemporaneous fan downstream (2.6 ± 0.6 km3) indicates that the latter did not trap the whole sediment load transported by the river. The alluvial fan was bypassed by 27 to 78% of this load toward its distal alluvial plain. If this value is well estimated, it implies a major volumetric partitioning of the deposits between the fan and the alluvial plain, with a very high sedimentation rate in the fan (1.97 ± 0.52 mm*y− 1) and a much lower one downstream (0.11 ± 0.11 mm*y− 1). However, this volumetric partitioning might only occur during periods with a very specific hydrological regime such as the Holocene deglaciation. Eventually, the peculiar sediment storage and release pattern within the Kuitun catchment and piedmont areas during the Pleistocene and Holocene complicates the calculation of mean paleodenudation rates using either sediment budgets or in situ produced cosmogenic nuclides

Exploiting satellite SAR for archaeological prospection and heritage site protection

Optical and Synthetic Aperture Radar (SAR) remote sensing has a long history of use and reached a good level of maturity in archaeological and cultural heritage applications, yet further advances are viable through the exploitation of novel sensor data and imaging modes, big data and high-performance computing, advanced and automated analysis methods. This paper showcases the main research avenues in this field, with a focus on archaeological prospection and heritage site protection. Six demonstration use-cases with a wealth of heritage asset types (e.g. excavated and still buried archaeological features, standing monuments, natural reserves, burial mounds, paleo-channels) and respective scientific research objectives are presented: the Ostia-Portus area and the wider Province of Rome (Italy), the city of Wuhan and the Jiuzhaigou National Park (China), and the Siberian “Valley of the Kings” (Russia). Input data encompass both archive and newly tasked medium to very high-resolution imagery acquired over the last decade from satellite (e.g. Copernicus Sentinels and ESA Third Party Missions) and aerial (e.g. Unmanned Aerial Vehicles, UAV) platforms, as well as field-based evidence and ground truth, auxiliary topographic data, Digital Elevation Models (DEM), and monitoring data from geodetic campaigns and networks. The novel results achieved for the use-cases contribute to the discussion on the advantages and limitations of optical and SAR-based archaeological and heritage applications aimed to detect buried and sub-surface archaeological assets across rural and semi-vegetated landscapes, identify threats to cultural heritage assets due to ground instability and urban development in large metropolises, and monitor post-disaster impacts in natural reserves

Pre‐symptomatic transmission of novel coronavirus in community settings

We used contact tracing to document how COVID‐19 was transmitted across 5 generations involving 10 cases, starting with an individual who became ill on January 27. We calculated the incubation period of the cases as the interval between infection and development of symptoms. The median incubation period was 6.0 days (interquartile range, 3.5‐9.5 days). The last two generations were infected in public places, 3 and 4 days prior to the onset of illness in their infectors. Both had certain underlying conditions and comorbidity. Further identification of how individuals transmit prior to being symptomatic will have important consequences.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163478/2/irv12773.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163478/1/irv12773_am.pd

Association of brain morphology and phenotypic profile in patients with unruptured intracranial aneurysm

IntroductionStudies have found a varying degree of cognitive, psychosocial, and functional impairments in patients with unruptured intracranial aneurysms (UIAs), whereas the neural correlates underlying these impairments remain unknown.MethodsTo examine the brain morphological alterations and white matter lesions in patients with UIA, we performed a range of structural analyses to examine the brain morphological alterations in patients with UIA compared with healthy controls (HCs). Twenty-one patients with UIA and 23 HCs were prospectively enrolled into this study. Study assessment consisted of a brain magnetic resonance imaging (MRI) scan with high-resolution T1-weighted and T2-weighted imaging data, a Montreal Cognitive Assessment (MoCA), and laboratory tests including blood inflammatory markers and serum lipids. Brain MRI data were processed for cortical thickness, local gyrification index (LGI), volume and shape of subcortical nuclei, and white matter lesions.ResultsCompared to the HCs, patients with UIA showed no significant differences in cortical thickness but decreased LGI values in the right posterior cingulate cortex, retrosplenial cortex, cuneus, and lingual gyrus. In addition, decreased LGI values correlated with decreased MoCA score (r = 0.498, p = 0.021) and increased white matter lesion scores (r = −0.497, p = 0.022). The LGI values were correlated with laboratory values such as inflammatory markers and serum lipids. Patients with UIA also showed significant regional atrophy in bilateral thalami as compared to the HCs. Moreover, the LGI values were significantly correlated with thalamic volume in the HCs (r = 0.4728, p = 0.0227) but not in the patients with UIA (r = 0.11, p = 0.6350).DiscussionThe decreased cortical gyrification, increased white matter lesions, and regional thalamic atrophy in patients with UIA might be potential neural correlates of cognitive changes in UIA

An Improved Segmentation Method for Automatic Mapping of Cone Karst from Remote Sensing Data Based on DeepLab V3+ Model

The South China Karst, a United Nations Educational, Scientific and Cultural Organization (UNESCO) natural heritage site, is one of the world’s most spectacular examples of humid tropical to subtropical karst landscapes. The Libo cone karst in the southern Guizhou Province is considered as the world reference site for these types of karst, forming a distinctive and beautiful landscape. Geomorphic information and spatial distribution of cone karst is essential for conservation and management for Libo heritage site. In this study, a deep learning (DL) method based on DeepLab V3+ network was proposed to document the cone karst landscape in Libo by multi-source data, including optical remote sensing images and digital elevation model (DEM) data. The training samples were generated by using Landsat remote sensing images and their combination with satellite derived DEM data. Each group of training dataset contains 898 samples. The input module of DeepLab V3+ network was improved to accept four-channel input data, i.e., combination of Landsat RGB images and DEM data. Our results suggest that the mean intersection over union (MIoU) using the four-channel data as training samples by a new DL-based pixel-level image segmentation approach is the highest, which can reach 95.5%. The proposed method can accomplish automatic extraction of cone karst landscape by self-learning of deep neural network, and therefore it can also provide a powerful and automatic tool for documenting other type of geological landscapes worldwide

Detect, Map, and Preserve Bronze and Iron Age Monuments along the Prehistoric Silk Road

Central Asia is rich in cultural heritage generated by thousands of years of human occupation. Aiming for a better understanding of Central Asia's archaeology and how this unique heritage can be protected, the region should be studied as a whole with regard to its cultural ties with China and combined efforts should be undertaken in shielding the archaeological monuments from destruction. So far, international research campaigns have focused predominantly on single-sites or small-scale surveys, mainly due to the bureaucratic and security related issues involved in cross-border research. This is why we created the Dzungaria Landscape Project. Since 2013, we have worked on collecting remote sensing data of Xinjiang including IKONOS, WorldView-2, and TerraSAR-X data. We have developed a method for the automatic detection of larger grave mound structures in optical and SAR data. Gravemounds are typically spatially clustered and the detection of larger mound structures is a sufficient hint towards areas of high archaeological interest in a region. A meticulous remote sensing survey is the best planning tool for subsequent ground surveys and excavation. In summer 2015, we undertook a survey in the Chinese Altai in order to establish ground-truth in the Hailiutan valley. We categorized over 1000 monuments in just three weeks thanks to the previous detection and classification work using remote sensing data. Creating accurate maps of the cemeteries in northern Xinjiang is a crucial step to preserving the cultural heritage of the region since graves in remote areas are especially prone to looting. We will continue our efforts with the ultimate aim to map and monitor all large gravemounds in Dzungaria and potentially neighbouring eastern Kazakhstan

A fluvial terrace record of late Quaternary folding rate of the Anjihai anticline in the northern piedmont of Tian Shan, China

Crustal shortening of the Tian Shan Range in northwest China has largely been accommodated by fold-and-thrust belts that mark the northern and southern mountain boundaries, which were formed during the basinward propagation of the deformation front of Tian Shan. Investigating the deformation rates of active folds (anticlines) in the mountain piedmonts within different timescales is important for understanding the mountain building and front propagation processes of the Tian Shan. In this study, we investigate the late Quaternary folding rate of the Anjihai anticline, one of the major anticlines in the northern piedmont of Tian Shan. Our study is based on optically stimulated luminescence (OSL) dating and topographic measurements of folded river terraces. Three well-preserved fluvial terraces across the Anjihai anticline were identified and dated to be 3.6 ± 0.1 ka, 9.0 ± 0.6 ka and 53.3 ± 2.2 ka, respectively. These terrace ages are combined with shortening and uplift of the terraces estimated using an area-conservation method and the terrace height profiles to evaluate the average shortening and uplift rates. Our results show that the minimum shortening rate of the Anjihai anticline is ~ 0.4 mm/a between 53 ka and 9 ka and ~ 1.1 mm/a over the past 9 ka, and the corresponding minimum uplift rates are ~ 0.5 mm/a and ~ 1.4 mm/a, respectively. If a local sedimentation rate of 0.3 mm/a is taken into consideration, the shortening rate is ~ 0.7 mm/a between 53 ka and 9 ka and ~ 1.3 mm/a since 9 ka, and the corresponding uplift rates are ~ 0.8 mm/a and ~ 1.5 mm/a, respectively. These data suggest that the Anjihai anticline has accommodated ~ 20-25% of the total shortening across the whole eastern Tian Shan (~ 5 mm/a) in the Holocene. Our results suggest that the Holocene is a relatively tectonically active time interval since the late Pleistocene. The late Quaternary shortening rate of the Anjihai anticline is much higher than its long-term average shortening rate (0.2 mm/a) since its formation at 7.4 Ma. A similar situation has also been observed for other active folds in the northern and southern piedmonts of Tian Shan. The higher late Quaternary folding rate is possibly attributed to the gradual propagation of the Tian Shan towards its northern and southern foreland basins in the Quaternary