Segmentation and lateral growth of intracratonic strike-slip faults in the northern Tarim Basin, NW China: influences on Ordovician fault-controlled carbonate reservoirs

Intracratonic strike-slip faults have been recognized as a major factor controlling the formation of fracture-cave carbonate reservoirs in deep buried basins, yet which properties and how the strike-slip faults influence reservoir distribution and their connectivity are still ambiguous. This uncertainty significantly restricts hydrocarbon exploration and development, such as in the Fuman oilfield, northern Tarim Basin, NW China. Using a high-resolution 3D seismic reflection survey and borehole data, we investigated the geometry and kinematic evolution of the FI17 fault zone in the Fuman oilfield. This fault zone is characterized by a single fault zone, pop-up or pull-apart structures, right-stepping en echelon normal faults, and much smaller displacement (<30 m) normal fault arrays from bottom to top. The FI17 fault zone consists of four genetic segments, including the extensional strike-slip duplex, Riedel left-lateral shear, right-stepping horsetail splay, and horizontal slip segments in map view. In particular, the formation of the ∼18 km Riedel shear zone is characterized by the growth and linkage of segmented shear faults (synthetic and secondary synthetic shears). We observed that the large-scale fault-controlled fracture-cave reservoirs are distributed in positions with wider fault zones, which are characterized by overlapping of neighboring secondary shear faults. Furthermore, the reservoir width examined in this study is natural logarithmic correlated (positively) to the fault zone width. The reservoirs linked by the same shear faults show better internal connectivity. The spatial coherence between fault geometry and reservoir features indicates that segmentation and lateral growth of intracratonic strike-slip faults controls the occurrence of fracture-cave reservoirs, which may provide support for reservoir prediction in the Fuman oilfield and other deeply buried fault-controlled carbonate reservoirs in general

Research on Bone Stick Text Recognition Method with Multi-Scale Feature Fusion

Bone sticks are composed of thin slices of animal bones created by ancient people, which mainly served the functions of fixing books, writing scripts, and divination. The bone stick script is an essential material for studying the history of Chinese Western Han script. Using a neural network for text recognition can quickly interpret ancient text, while extracting deeper semantic information, neural networks will also lose superficial image details. After multi-layer convolution and pooling of bone sticks, the continuous loss of superficial details affects classification accuracy. At the same time, the unbalanced distribution of bone stick quantity leads to a low recognition rate with small samples of bone sticks. Aiming to solve the above problems, a bone stick recognition method based on multi-scale features and focal loss function is proposed. Firstly, based on the residual network ResNet, the output features of the first layer and four Conv_x layers are pooled globally to reduce the feature dimension of each channel, and the channel splicing method is used to add different depths of base information to the original high-level features, which improves the detail feature extraction ability of the model. Secondly, in view of the unbalanced distribution of the bone stick data, the original cross-entropy loss function is replaced by the focus loss function, which increases the penalty for classification errors and improves the recognition rate of classes with few training samples. Experimental results show that the recognition accuracy of the proposed method on the bone stick data set is up to 90.5%

Research on Bone Stick Text Recognition Method with Multi-Scale Feature Fusion

Bone sticks are composed of thin slices of animal bones created by ancient people, which mainly served the functions of fixing books, writing scripts, and divination. The bone stick script is an essential material for studying the history of Chinese Western Han script. Using a neural network for text recognition can quickly interpret ancient text, while extracting deeper semantic information, neural networks will also lose superficial image details. After multi-layer convolution and pooling of bone sticks, the continuous loss of superficial details affects classification accuracy. At the same time, the unbalanced distribution of bone stick quantity leads to a low recognition rate with small samples of bone sticks. Aiming to solve the above problems, a bone stick recognition method based on multi-scale features and focal loss function is proposed. Firstly, based on the residual network ResNet, the output features of the first layer and four Conv_x layers are pooled globally to reduce the feature dimension of each channel, and the channel splicing method is used to add different depths of base information to the original high-level features, which improves the detail feature extraction ability of the model. Secondly, in view of the unbalanced distribution of the bone stick data, the original cross-entropy loss function is replaced by the focus loss function, which increases the penalty for classification errors and improves the recognition rate of classes with few training samples. Experimental results show that the recognition accuracy of the proposed method on the bone stick data set is up to 90.5%

Quantifying proportions of different material sources to loess based on a grid search and Monte Carlo model: A case study of the Ili Valley, Central Asia

The Ili Valley is among the main distribution areas of loess deposits in Xinjiang Province, Central Asia, while the provenance of Ili loess remains under debate. In this study, samples from near-surface loess, two types of topsoil and modern riverbed sediment were analyzed for their concentrations of major and trace geochemical elements to determine the relative proportions of different provenances of loess deposits in different zones of the Ili Valley. The results obtained by the grid search technology and Monte Carlo model indicated that the proximal material is dominated in the Ili loess. Alluvial-diluvial sediments as the main local material source have significantly influenced loess in the western region of Ili Valley. Moreover, this influence gradually decreases in the eastern region and the Zhaosu Basin. The proportion of modern riverbed sediment in the eastern Ili Valley is significantly lower than that in the Zhaosu Basin and is lowest in the western Ili Valley. However, the proportion of dust and topsoil type-II with the mean value of 11.8% and 7.2%, respectively, is highest in the western Ili Valley and lowest in the Zhaosu Basin. The complex natural background of the Ili Valley can be used to interpret the quantitative results and the geochemical characteristics of Ili loess from different regions. The reliability of the proposed method can be assessed by environmental indicators such as grain size, and geomorphic-hydrological background and other published records

Late Holocene hydroclimatic changes inferred from a karst peat archive in the western Guizhou Plateau, SW China

The paleoenvironmental implications of Ca-related indices of peat from karst regions are poorly understood. In this study, we analyze a 450-cm peat core drilled from a sub-alpine karst mountain in the western Guizhou Plateau, SW China. This core is analyzed for carbonate contents and loss on ignition (LOI). High-resolution X-ray fluorescence (XRF) core scanning was also performed to see the variation of chemical compositions. Based on these measurements and 12 accelerator mass spectrometry (AMS)C-14 dates, we reconstructed the history of hydroclimatic shifts in SW China and explored the significance of Ca-related indices. The reconstructed hydro climatic conditions were consistent with the stalagmite, lacustrine sediment, and peat records from the regions controlled by the Indian monsoon. Abrupt decreases in precipitation and temperature were clearly shown during the 4.2 ka and Little Ice Age (LIA) cold events. High carbonate contents in the Yejiping peat during the Medieval Warm Period (MWP) were linked to a warm and humid climate. Additionally, wavelet analysis shows that variations in Ca content have 500, 125, 103, 80, 58, 43, 20, and 12-a quasi-periods, which correspond to the Gleissberg, Pacific Decadal Oscillation (PDO), and Schwabe cycles. Our results highlight the importance of Ca related indices in peat deposits from karst depressions and provide a detailed description of the MWP and the LIA

Table2_Segmentation and lateral growth of intracratonic strike-slip faults in the northern Tarim Basin, NW China: influences on Ordovician fault-controlled carbonate reservoirs.XLSX

Intracratonic strike-slip faults have been recognized as a major factor controlling the formation of fracture-cave carbonate reservoirs in deep buried basins, yet which properties and how the strike-slip faults influence reservoir distribution and their connectivity are still ambiguous. This uncertainty significantly restricts hydrocarbon exploration and development, such as in the Fuman oilfield, northern Tarim Basin, NW China. Using a high-resolution 3D seismic reflection survey and borehole data, we investigated the geometry and kinematic evolution of the FI17 fault zone in the Fuman oilfield. This fault zone is characterized by a single fault zone, pop-up or pull-apart structures, right-stepping en echelon normal faults, and much smaller displacement (I17 fault zone consists of four genetic segments, including the extensional strike-slip duplex, Riedel left-lateral shear, right-stepping horsetail splay, and horizontal slip segments in map view. In particular, the formation of the ∼18 km Riedel shear zone is characterized by the growth and linkage of segmented shear faults (synthetic and secondary synthetic shears). We observed that the large-scale fault-controlled fracture-cave reservoirs are distributed in positions with wider fault zones, which are characterized by overlapping of neighboring secondary shear faults. Furthermore, the reservoir width examined in this study is natural logarithmic correlated (positively) to the fault zone width. The reservoirs linked by the same shear faults show better internal connectivity. The spatial coherence between fault geometry and reservoir features indicates that segmentation and lateral growth of intracratonic strike-slip faults controls the occurrence of fracture-cave reservoirs, which may provide support for reservoir prediction in the Fuman oilfield and other deeply buried fault-controlled carbonate reservoirs in general.</p

Table1_Segmentation and lateral growth of intracratonic strike-slip faults in the northern Tarim Basin, NW China: influences on Ordovician fault-controlled carbonate reservoirs.XLSX

Intracratonic strike-slip faults have been recognized as a major factor controlling the formation of fracture-cave carbonate reservoirs in deep buried basins, yet which properties and how the strike-slip faults influence reservoir distribution and their connectivity are still ambiguous. This uncertainty significantly restricts hydrocarbon exploration and development, such as in the Fuman oilfield, northern Tarim Basin, NW China. Using a high-resolution 3D seismic reflection survey and borehole data, we investigated the geometry and kinematic evolution of the FI17 fault zone in the Fuman oilfield. This fault zone is characterized by a single fault zone, pop-up or pull-apart structures, right-stepping en echelon normal faults, and much smaller displacement (I17 fault zone consists of four genetic segments, including the extensional strike-slip duplex, Riedel left-lateral shear, right-stepping horsetail splay, and horizontal slip segments in map view. In particular, the formation of the ∼18 km Riedel shear zone is characterized by the growth and linkage of segmented shear faults (synthetic and secondary synthetic shears). We observed that the large-scale fault-controlled fracture-cave reservoirs are distributed in positions with wider fault zones, which are characterized by overlapping of neighboring secondary shear faults. Furthermore, the reservoir width examined in this study is natural logarithmic correlated (positively) to the fault zone width. The reservoirs linked by the same shear faults show better internal connectivity. The spatial coherence between fault geometry and reservoir features indicates that segmentation and lateral growth of intracratonic strike-slip faults controls the occurrence of fracture-cave reservoirs, which may provide support for reservoir prediction in the Fuman oilfield and other deeply buried fault-controlled carbonate reservoirs in general.</p

Paleoenvironment change and its impact on carbon and nitrogen accumulation in the Zoige wetland, northeastern Qinghai-Tibetan Plateau over the past 14,000 years

As the largest alpine wetland and peat deposition area in China, the Zoige wetland is climatically sensitive. The organic matter (OM) in peat stores copious environmental information. Here we report new data on the organic geochemistry of a 4.5 m peat profile HY2014 from southern Zoige wetland. Based on closely spaced accelerator mass spectrometry (AMS) C-14 dating, we established a high-resolution geochronological framework beginning at 14,057 a BP. Moreover, we estimated the sedimentation flux of TOC and TN (SFs) and their influencing factors. Before 10,916 a BP, the lake shrunk and peat began to develop under cold and dry conditions, and SFs were at their lowest values due to low productivity. More OM originated from hydrophyte and marsh plants. From 10,916 to 3050 a BP, peat was widely and well developed, and the climate was warm and humid, despite a cooling and drying trend. The HY2014 profile experienced an optimum climate during 10,91626000 a BP, when SFs had the highest values that benefited from high productivity, and OM mainly originated from terrestrial plants. After 3050 a BP, the climate was the coldest and driest. The high SFs over the past 2000 a BP were mainly resulted from the low decomposition rate. The plant community, primary productivity, and decomposition rate were closely linked with the temporal variation of SFs. The environment change was mainly controlled by summer solar insolation, and the Zoige wetland was significantly influenced by the Indian summer monsoon