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There are rich geothermal resources in China and they are widely distributed. After years of continuous exploration and production, most of the shallow geothermal resources have been explored and the current exploration mainly focuses on deep ones. Among a great many geophysical exploration methods, seismic survey is the most effective means of geothermal resource exploration and production, but its weak seismic reflection signal, low S/N ratio and poor imaging of thermal reservoirs due to the seismic geological conditions restrict the production and utilization of deep geothermal resources. It considers through the analysis of the geophysical characteristics of the thermal reservoir that the main causes for the weak seismic reflection signals from deep thermal reservoirs are (1) the shielding effect of the strong wave impedance interface between the thermal reservoir and the caprocks; (2) the small reflection coefficient inside the thermal reservoir; and (3) the serious absorption and attenuation of high-temperature fluids such as hydrothermal fluids and steam in the thermal reservoirs by seismic waves. Accordingly, a series of seismic data acquisition technologies are proposed based on the high-precision vibroseis low-frequency shooting, high-sensitivity geophones long-spread receiving and small bin size highfold technologies, and their application in the seismic acquisition of dry-hot rocks (HDR) in Gonghe Basin, Qinghai, shows a very good application effect. [ABSTRACT FROM AUTHOR]

• Novel approach: our study proposes a 3D U-shaped neural network that can accurately simulate the temperature field of hot dry rocks in both space and time dimensions. This approach is a significant advancement as previous methods have addressed these tasks separately, presenting challenges. • Improved accuracy: by incorporating an attention mechanism and residual structure, our neural network captures the nonlinear relationship between the temperature field and rock strata parameters more accurately. This leads to more precise temperature field simulations of hot dry rocks and enhances our understanding of the system. • Practical implications: the simulated temperature field provides valuable insights into the effects of different geological formations on hot dry rocks. This information is crucial for predicting and exploiting hot dry rock geothermal reserves. Our findings lay the foundation for further research and development in this field and offer practical implications for the utilization of hot dry rock geothermal resources. Hot dry rock has emerged as a crucial renewable resource with a potential to provide significant energy to China. Accurately simulating the temperature field of hot dry rocks in space is essential in estimating their reserves. Moreover, predicting the temperature change curve of hot dry rocks over time is crucial for research in the field. Although these tasks are interrelated and share a common ground of simulating the temperature of hot dry rocks, previous approaches have dealt with them separately, each being challenging. In this study, we propose a 3D U-shaped deep-time neural network that can extract the nonlinear relationship between the temperature field and rock strata parameters, thereby enabling the simulation of the temperature field of hot dry rocks in both space and time dimensions. The proposed neural network, which incorporates an attention mechanism and residual structure, can incorporate multiple rock parameters and geological structures, leading to more accurate simulation of the temperature field of hot dry rocks. To train the network, we constructed extensive datasets based on granite rock parameters and actual geological structures, with the temperature fields simulated by the finite element method serving as labels. The resulting trained network model can successfully emulate the complex hot dry rock model, reducing the workload by combining the two networks into one. Furthermore, the simulated temperature field allows the observation of the effect of different geological activities on hot dry rocks. Network simulation has shown notable advancements in efficiency compared to traditional finite element methods. Moreover, it offers the advantage of exploring the impact of distinct geological structures on geothermal reservoirs in a spatial context. Additionally, it allows for the observation of temporal variations in the temperature distribution across different geological strata during different time periods. Thereby laying the groundwork for further prediction and exploitation of hot dry rock geothermal reserves. [ABSTRACT FROM AUTHOR]

The concentrations of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) and organic carbon in surface sediments, collected from the southern Bohai Bay, were determined to assess the potential contamination and determine the environmental risks associated with heavy metals. Results showed that heavy metal concentrations in the sediments generally met the China Marine Sediment Quality criteria. Both the ecotoxicological index and the potential ecological risk index suggest that the combined ecological risk of the six studied metals may be low, with the highest ecotoxicological potential zones located in the offshore area. The methods of enrichment factor and geoaccumulation index suggested that elevated concentrations of Cd, Cr, and Ni are presented in the region. Multivariate analysis also indicated that the lithogenic factor dominates the distribution of most part of the considered metals in the study area, whereas Cd and Cr are clearly influenced by anthropogenic inputs. The results of this study are likely to be a useful tool to authorities in charge of sustainable marine management. [ABSTRACT FROM AUTHOR]

Abstract: We present a provenance study of core ZK2 from the Huanghe (Yellow River) Delta in order to assess the impacts of climate change on the sediment supplies during the last glacial–interglacial cycle. Facies analysis and sequence stratigraphy methods are used to construct the age model. Sr isotopic compositions of ZK2 range from 0.716389 to 0.723884, with 87Sr/86Sr increased with decreasing grain size. Nd and Pb isotopic compositions display two large major excursions during Marine Oxygen Isotope stages (MIS) 2 and 4, with less radiogenic εNd and lower 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb values during these periods. These excursions have been explained in terms of changes in the mixing proportion of sediments from the Loess Plateau and Ordos Plateau, resulting from East Asian monsoon intensity variations. The weak summer monsoon precipitation resulted in decreased erosion of Loess Plateau during MIS 2, 4 and the middle of MIS 3. Meanwhile, both the intensified East Asian winter monsoon and the southward expansions of Mu Us desert significantly enhanced the eolian sand entering the Huanghe. Therefore, our results highlight the impact of monsoon variability on erosion patterns in the Huanghe basin. [Copyright &y& Elsevier]

Although the geochemical and mineralogical characteristics and provenance of Permian-Triassic boundary (PTB) widespread volcanic ashes from southern China have been well investigated, the volcanic ashes just prior to the end-Permian mass extinction (EPME) have rarely been studied. This paper presents the mineralogical and geochemical compositions of volcanic ashes from the latest Permian coal-bearing strata of southwest China. Based on the relative abundances of kaolinite and mixed-layer illite/smectite (I/S), the volcanic ashes in the present study can be divided into tonsteins and K-bentonites, which are dominated by kaolinite and I/S, respectively. The I/S in K-bentonites formed during burial diagenesis in a non-marine environment, indicated by their low contents of sulfur and low ratios of Sr/Ba. Based on the general geothermal gradient and vitrinite reflectance of coals, the I/S was deduced to have formed under a temperature less than 100 °C. Collectively, the occurrence of vermicular kaolinite, as well as high-temperature quartz and euhedral primary zircon identified in tonstein samples indicate an intermediate-felsic pyroclastic origin for the volcanic ashes, while rounded quartz and mica grains both in tonsteins and K-bentonites reflect the products of erosion from sediment source regions. The negative Eu anomalies, rare earth elements (REY) distribution patterns, low contents of Sc, V, Cr, Co, Ni and Zn, and Al 2 O 3 /TiO 2 values, suggest that the tonsteins and K-bentonites are related to felsic volcanic eruptions. The relationship between Al 2 O 3 /TiO 2 vs. Nb/Yb and Al 2 O 3 /TiO 2 vs. Zr/TiO 2 ratios indicate that the tonsteins and K-bentonites were derived from at least two felsic sources: (1) some distal volcanic arc(s) and (2) the top of the Kangdian Upland exposing the alkaline-felsic volcanic rocks formed during the waning activity of the Emeishan plume and the basement of the Kangdian Upland exposing older felsic rocks. • Seven volcanic ash layers were recognized in the latest Permian coal-bearing strata. • The volcanic ashes with felsic origin are recognized as tonsteins and K-bentonites. • The volcanic ashes were associated with the Emeishan plume and the volcanic arcs. [ABSTRACT FROM AUTHOR]

The coal-hosted Ge deposit (Early Cretaceous) at Wulantuga, Inner Mongolia, northern China, is one of the largest Ge deposits in the world. Although the origin, modes of occurrence, and spatial distribution of Ge in this deposit have been investigated by several studies, the provenance and pathways of Ge from the source to the deposit are largely unknown. In this study, we investigated the 87Sr/86Sr values in the high-Ge coal of the Wulantuga deposit and the stratigraphically-equivalent low-Ge coal of the No. 1 Pit, both from the Shengli Coalfield, Inner Mongolia, northern China. In addition to an organic association, Sr and Ca in the high-Ge and low-Ge coals also occur in gypsum. The water-soluble Sr (i.e., in gypsum) in the high-Ge coal (Ge concentrations: 45–1170 ppm, 273 ppm on average, whole coal basis) has 87Sr/86Sr values in the range of 0.710411 to 0.710633 (with an average of 0.710478). In contrast, the low-Ge coal (Ge concentrations: up to 4.23 ppm, 0.45 ppm on average, whole coal basis) has lower 87Sr/86Sr values in two sub-groups, a low range of 0.709896–0.71005 (with an average of 0.709736) and a high range of 0.710173–0.710547 (with an average of 0.710329 and dominantly in the range of 0.710173–0.710406). The higher 87Sr/86Sr values in the high-Ge coals indicate that the highly-elevated concentration of Ge is associated with a local source of radiogenic Sr. The enrichment of Ge in the coal is due to several consecutive processes. Surface waters penetrated deeply into granite and dissolved at least partially more soluble phases of the granite. The Ge-rich solution flowed over ground or underground into the Shengli Coalfield and Ge precipitated in the peat, the precursor of the coal investigated in the coalfield. The 87Sr/86Sr values of the water-soluble fraction, the elemental compositions of high-Ge and low-Ge coals, and the geomorphological setting of the coalfield point to the Hercynian granodiorite intrusion on the nearby SE margin of the Shengli Coalfield as the primary source of Ge in the Wulantuga coal-hosted Ge deposit. In addition to serving as an indicator of the mode of formation of the coal-hosted Ge deposit, the 87Sr/86Sr values and their spatial distribution can provide an indication for the hydrological pathways of the mineralising fluid. • The Sr in gypsum in the high-Ge coals has 87Sr/86Sr values from 0.710411 to 0.710633. • The Sr in gypsum in the low-Ge coal has lower 87Sr/86Sr values, 0.709896–0.710547. • The higher 87Sr/86Sr values in the high-Ge coals indicate a grantic Ge source. [ABSTRACT FROM AUTHOR]

• Surface pollen concentration is proportional to content of silt and clay. • Both Pinus and fern spores showed a gradual increase toward the deeper waters. • Yellow River input dominated the pollen provenance in the Bohai Sea. • Circulation are the main driving forces for pollen-spore transport. • Fluctuations of fossil Pinus and herbs revealed the sea level and climate changes. To elucidate the mechanisms responsible for pollen and spore transportation and deposition in the Bohai Sea, fully covered seafloor-surface sediment samples were collected for palynological and grain size analysis. The results reveal that the pollen and spore concentrations were higher in the head of Liaodong Bay and in the muddy area of the Bohai Sea. The Yellow River was the main source of pollen and spores in the Bohai Sea. The sediments with relatively high pollen concentrations consisted mainly of clay and fine silt, whereas sediment with lower pollen concentrations was mostly fine sand. In addition, the percentages of Pinu s pollen and pteridophyte spores increased with increasing sea water depth, while other arboreal (excluding Pinus) and herbaceous pollen generally decreased with increasing distance from the shore. The relationship between the pollen taxa and the water depth of the sampling points shows that the fluvial water plays a predominant role in pollen transmission within 20 m of water depth, while the wind is the main driving force for pollen transmission when the water depth exceeds 20 m. Although Pinus pollen and pteridophyte spores were over-represented, there was good correlation between marine pollen signals and terrestrial vegetation. Apart from the influence of rivers and wind on pollen and spore deposition, the tidal currents and circulation were also main force responsible for transporting sediment and determining the differentiation of pollen and spores in the Bohai Sea. The comparison of pollen and spore percentages between surface sediment and fossil records from sedimentary cores made it possible to identify changes in pollen sources and transport mechanisms. Meanwhile, the percentage fluctuations of fossil Pinus and herbaceous pollen revealed concomitant changes of the sea level and climate. These findings are of paramount importance to the interpretation of Quaternary marine pollen data from the Bohai Sea, China. [ABSTRACT FROM AUTHOR]

In an effort to assess the potential contamination and determine the environmental risks associated with heavy metals, the surface sediments in Liaodong Bay, northeast China, were systematically sampled and analyzed for the concentrations of Cu, Pb, Zn, Cr, Ni, As, and Hg. The metal enrichment factor (EF) and geoaccumulation index (I geo) were calculated to assess the anthropogenic contamination in the region. Results showed that heavy metal concentrations in the sediments generally met the criteria of China Marine Sediment Quality (GB18668-2002); however, both EF and I geo values suggested the elevation of Pb concentration in the region. Based on the effect-range classification (TEL-PEL SQGs), Cu, Pb, Ni, and As were likely to pose environment risks, and the toxic units decreased in the order: Ni > Pb > Cr > Zn > As > Cu > Hg. The spatial distribution of ecotoxicological index (mean-ERM-quotient) suggested that most of the surface sediments were "low-medium" priority zone. Multivariate analysis indicated that the sources of Cr, Ni, Zn, Cu, and Hg resulted primarily from parent rocks, and Pb or As were mainly attributed to anthropogenic sources. The results of this study would provide a useful aid for sustainable marine management in the region.

Sixty-nine samples of surface sediments (0-5 cm) recovered from the eastern Beibu Bay were analyzed for TOC and heavy metals to examine the element distribution pattern and potential pollutant sources. The sediments in the study area are characterized by variable heavy metal concentrations that are comparable with those of the surrounding regions. Obvious positive correlations were observed amongst the concentrations of Zn, Cr, Pb, Cd, Cu and the clay contents, suggesting that fine clay particles are important carriers of trace metals in the sediments. Hg and As show a considerable/low positive correlation with TOC, indicating that organic matter may play a discernible role in the sediment chemistry. Cd contamination was detected in the north of the study area primarily due to the input of phosphate fertilizers carried by rivers. In comparison, Zn, Cr, Pb, and partly Cu are predominantly sourced from lithogenic components, and Hg and As are mainly from organic matter related to anthropogenic input., (Published by Elsevier Ltd.)