Upper Paleozoic Transitional Shale Gas Enrichment Factors: A Case Study of Typical Areas in China

Based on the shale gas research experience in North America, large-scale geological evaluations have been conducted in China to determine the enrichment characteristics of deep marine shale gas, leading to the discovery of the Fuling, Changning and Weiyuan shale gas fields. However, research on Upper Paleozoic transitional shale gas remains limited, restricting the subsequent exploration and development. Therefore, taking the Lower Permian Shanxi and Pennsylvanian Taiyuan Formations in the northeastern Ordos Basin and the Upper Permian Longtan Formation in southwestern Guizhou as examples, gas logging, gas desorption, thermal simulation, maximum vitrinite reflectance (Rmax), and X-ray diffraction (XRD) were used to study the influence of lithological associations, sedimentary facies, gas generation thresholds, and pore evolution on transitional shale gas, and then Upper Paleozoic transitional shale gas enrichment factors of the northeastern Ordos Basin and southwestern Guizhou were analysed. The results show that carbonaceous mudstone adjacent to coal seams presents a high gas content level, and is primarily developed in swamps in the delta plain environment, and swamps and lagoons in the barrier coastal environment. The gas generation threshold maturity (Rmax) of transitional shale is 1.6% and the corresponding threshold depths of the northeastern Ordos Basin and southwestern Guizhou are estimated to be 2265 m and 1050 m. Transitional shale pore evolution is jointly controlled by hydrocarbon generation, clay minerals transformation, and compaction, and may have the tendency to decrease when Rmax < 1.6% or Rmax > 3.0%, but increase when Rmax ranges between 1.6% and 3.0%, while the main influential factors of pore evolution differ in each period. Continuous distribution of transitional shale gas enrichment areas can be formed along the slope adjacent to coal seams with a moderate maturity range (1.6%–3.0%) in the northeastern Ordos Basin, and transitional shale gas can be enriched in the areas adjacent to coal seams with a moderate maturity range (1.6%–3.0%), abundant fractures, and favorable sealing faults in southwestern Guizhou

The fallout from Fukushima Daiichi nuclear accident profiles a new dating reference in ice and comparison with the Chernobyl accident

Absolute-age dating horizons play a pillar role in the reconstruction of an ice core chronology. In the modern era, these have included the global fallout from massive volcanic eruptions, atmospheric and marine thermonuclear weapons testing and nuclear accidents. After the occurrence of the Fukushima Daiichi nuclear accident (FDNA) on March 11 2011, the simulation of the radioactivity from the FDNA by a dispersion model (HYSPLIT) shows that the nuclides reached the study area in late March, consistent with the ground measurements in Xi’an, Lanzhou and Urumqi. To investigate the deposition of radioactivity resulting from the FDNA, we collected snowpack samples from four glaciers (i.e. Glacier No. 1, Glacier No. 72, Qiyi and Shiyi glaciers, respectively) in northwestern China and analysed them for total β activity (TBA). The measured TBA in the FDNA layers were increased by two to four times, compared with the averages in the non-FDNA layers. We revisited Glacier No. 1 in 2018 and studied a much deeper snow-pit profile for the TBA, seven years after the first-time investigation into a relatively shallow snow pit in 2011. The TBA concentrated in a dust layer and became more significant in 2018 compared to that in 2011. We compared the TBA in Glacier No. 1 with that in the Muztagata glacier from the Chernobyl accident in 1986, and the depositions of radioactivity in the two High-Asian glaciers were comparable. We conclude that the FDNA formed a distinctly new lasting reference in the snow, which could help date the snow and ice in the Northern Hemisphere

A Novel Detection Framework About Conditions of Wearing Face Mask for Helping Control the Spread of COVID-19

Properly wearing a face mask has become an effective way to limit the COVID-19 transmission. In this work, we target at detecting the fine-grained wearing state of face mask: face without mask, face with wrong mask, face with correct mask. This task has two main challenging points: 1) absence of practical datasets, and 2) small intra-class distance and large inter-class distance. For the first challenging point, we introduce a new practical dataset covering various conditions, which contains 8635 faces with different wearing status. For the second challenging point, we propose a novel detection framework about conditions of wearing face mask, named Context-Attention R-CNN, which enlarge the intra-class distance and shorten inter-class distance by extracting distinguishing features. Specifically, we first extract the multiple context feature for region proposals, and use attention module to weight these context feature from channel and spatial levels. And then, we decoupling the classification and localization branches to extract more appropriate feature for these two tasks respectively. Experiments show that the Context-Attention R-CNN achieves 84.1% mAP on our proposed dataset, outperforming Faster R-CNN by 6.8 points. Moreover, Context-Attention R-CNN still exceed some state-of-the-art single-stage detectors

Long-term changes in the snow–firn pack stratigraphy on Ürümqi glacier No. 1, eastern Tien Shan, China

ABSTRACT. We report on changes to the snowpack of Ürümqi glacier No. 1, eastern Tien Shan, China, resulting from climate change between 1961 and 2005. Data from more than 120 snow pits were used to investigate temporal changes in the snow stratigraphy for three periods 1961–62, 1980–83 and 2002–05. Both the thickness and structure of the snow were found to be significantly altered by climatic warming. The proportion of coarse-grained firn, which is usually formed by infiltration water, was found to have increased from 40 % to 65 % over the period 1961–2005, and the distribution of the glacier zones also changed significantly, with all boundaries moving up-slope. The recrystallization– infiltration zone disappeared in 1989. The mean ablation rate over the melt season increased by ��26

Correction of precipitation measurement for weighing precipitation gauges in a glacierized basin in the Tianshan Mountains

Precipitation is one of the most important climatological data for global hydrothermal cycle and climate change. The accuracy of precipitation data not only directly affects the hydrological processes, but also plays an important role in the climate and hydrology at regional and global scales. According to the in situ datasets, the precipitation measurement in automatic weather stations for Geonor T-200B was corrected by the World Meteorological Organization Solid Precipitation Intercomparison Experiment (WMO-SPICE) transfer functions. The parameters of transfer functions were tested and recalibrated by the local datasets. The results showed that the transfer functions showed better performance after recalibrating parameters by the local datasets. The root-mean-square error (RMSE) and mean bias decreased by an average of 34% and 42%, respectively. The corrected snowfall increased by 7% (14 mm) at the test station. Then, the new parameters were used in other automatic weather stations to correct precipitation, and it was found that solid precipitation was underestimated by 13% on the glacier surface affected by wind speed. Moreover, according to the corrected precipitation datasets observed in automatic weather stations and national meteorological stations, the precipitation–altitude relationship in the Urumqi River Basin was analyzed. The annual precipitation gradient was 115 mm km-1, and the maximum seasonal altitude occurred in summer with a value of 35 mm km-1 and in autumn with the lowest value of 1 mm km-1. When considering precipitation on the glacier surface, the yearly precipitation gradient was increased with the value of 158 mm km -1 in 2019

Geodetic Mass Balance of Haxilegen Glacier No. 51, Eastern Tien Shan, from 1964 to 2018

The eastern Tien Shan hosts substantial mid-latitude glaciers, but in situ glacier mass balance records are extremely sparse. Haxilegen Glacier No. 51 (eastern Tien Shan, China) is one of the very few well-measured glaciers, and comprehensive glaciological measurements were implemented from 1999 to 2011 and re-established in 2017. Mass balance of Haxilegen Glacier No. 51 (1999–2015) has recently been reported, but the mass balance record has not extended to the period before 1999. Here, we used a 1:50,000-scale topographic map and long-range terrestrial laser scanning (TLS) data to calculate the area, volume, and mass changes for Haxilegen Glacier No. 51 from 1964 to 2018. Haxilegen Glacier No. 51 lost 0.34 km2 (at a rate of 0.006 km2 a−1 or 0.42% a−1) of its area during the period 1964–2018. The glacier experienced clearly negative surface elevation changes and geodetic mass balance. Thinning occurred almost across the entire glacier surface, with a mean value of −0.43 ± 0.12 m a−1. The calculated average geodetic mass balance was −0.36 ± 0.12 m w.e. a−1. Without considering the error bounds of mass balance estimates, glacier mass loss over the past 50 years was in line with the observed and modeled mass balance (−0.37 ± 0.22 m w.e. a−1) that was published for short time intervals since 1999 but was slightly less negative than glacier mass loss in the entire eastern Tien Shan. Our results indicate that Riegl VZ®-6000 TLS can be widely used for mass balance measurements of unmonitored individual glaciers