Tanlu fault zone(TLFZ)is the largest active fault zone in eastern China.It is characterized by complex tectonic evolution and multiple faults and marks the boundary between the North and South China blocks.An indepth ...Tanlu fault zone(TLFZ)is the largest active fault zone in eastern China.It is characterized by complex tectonic evolution and multiple faults and marks the boundary between the North and South China blocks.An indepth understanding of the distinct crustal structures of both parts of the TLFZ will provide valuable insights into the lithospheric and crustal thinning in eastern China,extensive magmatism since the Mesozoic,and formation mechanisms of metallogenic belts along the Yangtze River.In this study,a two-layer H-κstacking approach was adopted to estimate the thicknesses of the sediment and crystalline crust as well as the corresponding vP/vS ratios based on high-quality teleseismic P-wave receiver functions recorded by permanent and temporary stations in and around the TLFZ.The geological units in the study region were delineated,especially the crustal structures beneath extensive sedimentary basins on both sides of the TLFZ.The following conclusions can be drawn:(1)The crustal thickness in and around the TLFZ greatly varies depending on the segment.In the northern segment,the crust is relatively thin beneath the eastern part of the Songliao Basin,a broad uplift of the Moho can be observed,and the Moho descends from south to north.The crust below the central and southern segments becomes thinner from west to east.The thickness of the crust is less than 30 km toward the eastern side of the boundary between the Jiangsu and Anhui provinces,that is,significantly thinner than in other areas.In terms of the vP/vS ratios,high anomalies were detected in the central-southern segments of the TLFZ,indicating the upwelling of deep mantle magma via deep faults.(2)Positive isostatic gravity anomalies were observed in the eastern part of the northern segment of the TLFZ and in the eastern part of the Suwan segment.The crustal thickness is smaller than that obtained from the Airy model of isostasy.This suggests that the lower crust in this area may have experienced intensive transformation processes,which may be related to crustal thinning(caused by crustal extension)and the strong uplift of the mantle in eastern China.The isostatic gravity anomalies between the eastern and western parts of the TLFZ indicate that the fault zone plays a dominant role in controlling the development of the deep crustal structure.(3)Significant crustal thinning was observed beneath the eastern part of the boundary between the Jiangsu and Anhui provinces in the southern segment of the TLFZ,suggesting that this area is prone to lithospheric thinning of the North China Craton.Due to the subduction,compression,and retreat of the Paleo-Pacific Plate during the Yanshanian Period as well as the dehydration of subducting oceanic crust(within subduction zones),the asthenosphere and oceanic crust in eastern China partially melted,resulting in mantle enrichment.The basic magma from the mantle is accumulated at the base of the crust,leading to magmatic underplating.In areas with weak topography toward the east of the TLFZ,magma rises to the upper crust and surface,resulting in the enrichment of multiple metal deposits in this area.展开更多
[Objectives]This study was conducted to achieve rapid and accurate detection of protein content in rice with a particle size of 1.0 mm.[Methods]A multi-model fusion strategy was proposed on the basis of Stacking ensem...[Objectives]This study was conducted to achieve rapid and accurate detection of protein content in rice with a particle size of 1.0 mm.[Methods]A multi-model fusion strategy was proposed on the basis of Stacking ensemble learning.A base learner pool was constructed,containing Partial Least Squares(PLS),Support Vector Machine(SVM),Deep Extreme Learning Machine(DELM),Random Forest(RF),Gradient Boosting Decision Tree(GBDT),and Multilayer Perceptron(MLP).PLS,DELM,and Linear Regression(LR)were used as meta-learner candidates.Employing integer coding technology,systematic dynamic combinations of base learners and meta-learners were generated,resulting in a total of 40 non-repetitive fusion models.The optimal combination was selected through a comprehensive evaluation based on multiple assessment indicators.[Results]The combination"PLS-DELM-MLP-LR"(code 1367)achieved coefficients of determination of 0.9732 and 0.9780 on the validation set and independent test set,respectively,with relative root mean square errors of 2.35%and 2.36%,and residual predictive deviations of 6.1075 and 6.7479,respectively.[Conclusions]The Stacking fusion model significantly enhances the predictive accuracy and robustness of spectral quantitative analysis,providing an efficient and feasible solution for modeling complex agricultural product spectral data.展开更多
文摘Tanlu fault zone(TLFZ)is the largest active fault zone in eastern China.It is characterized by complex tectonic evolution and multiple faults and marks the boundary between the North and South China blocks.An indepth understanding of the distinct crustal structures of both parts of the TLFZ will provide valuable insights into the lithospheric and crustal thinning in eastern China,extensive magmatism since the Mesozoic,and formation mechanisms of metallogenic belts along the Yangtze River.In this study,a two-layer H-κstacking approach was adopted to estimate the thicknesses of the sediment and crystalline crust as well as the corresponding vP/vS ratios based on high-quality teleseismic P-wave receiver functions recorded by permanent and temporary stations in and around the TLFZ.The geological units in the study region were delineated,especially the crustal structures beneath extensive sedimentary basins on both sides of the TLFZ.The following conclusions can be drawn:(1)The crustal thickness in and around the TLFZ greatly varies depending on the segment.In the northern segment,the crust is relatively thin beneath the eastern part of the Songliao Basin,a broad uplift of the Moho can be observed,and the Moho descends from south to north.The crust below the central and southern segments becomes thinner from west to east.The thickness of the crust is less than 30 km toward the eastern side of the boundary between the Jiangsu and Anhui provinces,that is,significantly thinner than in other areas.In terms of the vP/vS ratios,high anomalies were detected in the central-southern segments of the TLFZ,indicating the upwelling of deep mantle magma via deep faults.(2)Positive isostatic gravity anomalies were observed in the eastern part of the northern segment of the TLFZ and in the eastern part of the Suwan segment.The crustal thickness is smaller than that obtained from the Airy model of isostasy.This suggests that the lower crust in this area may have experienced intensive transformation processes,which may be related to crustal thinning(caused by crustal extension)and the strong uplift of the mantle in eastern China.The isostatic gravity anomalies between the eastern and western parts of the TLFZ indicate that the fault zone plays a dominant role in controlling the development of the deep crustal structure.(3)Significant crustal thinning was observed beneath the eastern part of the boundary between the Jiangsu and Anhui provinces in the southern segment of the TLFZ,suggesting that this area is prone to lithospheric thinning of the North China Craton.Due to the subduction,compression,and retreat of the Paleo-Pacific Plate during the Yanshanian Period as well as the dehydration of subducting oceanic crust(within subduction zones),the asthenosphere and oceanic crust in eastern China partially melted,resulting in mantle enrichment.The basic magma from the mantle is accumulated at the base of the crust,leading to magmatic underplating.In areas with weak topography toward the east of the TLFZ,magma rises to the upper crust and surface,resulting in the enrichment of multiple metal deposits in this area.
文摘董志塬地区位于黄土高原中心地带,滑坡灾害频发,亟需明确滑坡易发性分区,以支持该区域滑坡隐患的科学防控。因此,本文以董志塬为研究区,选取高程、坡向和NDVI等12个影响因素作为评价因子,基于频率比(frequency ratio,FR)模型,结合随机森林(random forest,RF)与人工神经网络(artificial neural network,ANN)模型开展滑坡静态易发性评价,并分析各因子对评价精度的贡献。结果表明,FRRF和FR-ANN模型的曲线下面积(area under the curve,AUC)值分别为0.922和0.918,表明FR-RF模型在董志塬滑坡易发性评价中的精度更高。坡度、坡向和道路密度对滑坡易发性的贡献率分别为16.7%、15.3%和1.4%。为克服地形复杂和数据更新滞后的问题,本文将FR-RF模型的易发性结果与InSAR Stacking结果相结合,将静态滑坡易发性评价精度由6.9%提升到8.1%。动态易发性结果表明,董志塬滑坡高易发区主要分布于河流沿岸,占总面积的6.5%,该区域的滑坡数量占总滑坡数的23.6%,滑坡密度15.7个/km^(2)。低易发区主要位于远离河流的中部区域,占总面积的81.7%,滑坡数量占总滑坡数的57.8%,滑坡密度4.7个/km^(2)。本研究通过融合InSAR Stacking方法,解决了静态滑坡易发性评价数据更新滞后问题,减少了假阴性错误,为传统滑坡易发性评价赋予了时效性,可以实现董志塬滑坡易发性动态评价,为灾害防治提供了重要数据支持。
文摘[Objectives]This study was conducted to achieve rapid and accurate detection of protein content in rice with a particle size of 1.0 mm.[Methods]A multi-model fusion strategy was proposed on the basis of Stacking ensemble learning.A base learner pool was constructed,containing Partial Least Squares(PLS),Support Vector Machine(SVM),Deep Extreme Learning Machine(DELM),Random Forest(RF),Gradient Boosting Decision Tree(GBDT),and Multilayer Perceptron(MLP).PLS,DELM,and Linear Regression(LR)were used as meta-learner candidates.Employing integer coding technology,systematic dynamic combinations of base learners and meta-learners were generated,resulting in a total of 40 non-repetitive fusion models.The optimal combination was selected through a comprehensive evaluation based on multiple assessment indicators.[Results]The combination"PLS-DELM-MLP-LR"(code 1367)achieved coefficients of determination of 0.9732 and 0.9780 on the validation set and independent test set,respectively,with relative root mean square errors of 2.35%and 2.36%,and residual predictive deviations of 6.1075 and 6.7479,respectively.[Conclusions]The Stacking fusion model significantly enhances the predictive accuracy and robustness of spectral quantitative analysis,providing an efficient and feasible solution for modeling complex agricultural product spectral data.
