Pub Date : 2024-10-24DOI: 10.1016/j.jseaes.2024.106377
Muhammad Tayyab Naseer
<div><div>Quantitative seismic reservoir characterization is among the finest advancements in seismic technologies for sub-surface exploration of fluvial depositional systems (FDSS). These FDSS energy resources are combinations of thinly distributed gas-bearing trapping configurations such as the meander sandy channels (CH) along with aggradational parasequences (PBARS) of transgressive system tract (TST), which are developed during the extensive rise of sea-level followed by the rigorous standstill, and hence, which fills the PBARS and CH stratigraphic traps with possible hydrocarbons due to vertical and lateral changes in the facies. These thin-bedded CH and PBARS are very sensitive to a certain frequency component, which bandlimited seismic amplitudes (product of density and velocity) fail to quantify the paleo-thickness, paleo-velocities, paleo-densities, paleo-inclinations, paleo-geomorphology, vertical and lateral extents etc. of the stratigraphic traps. These parameters provide deep insights for quantitative-based stratigraphic reservoir characterizations. This study utilizes the spectral acoustic waveform seismic components and broadband spectrally-decomposed acoustic spectral waveform-based instantaneous lateral thickness variability static simulations (SLTRS) to quantify the FDSS of Southwest Pakistan. The 9–57 Hz bandwidth processed frequency volume reveals a poor tuning frequency component of 28 Hz and lateral extent of the stratigraphic, which failed to predict the direct geomorphology of PBARS and CH. 43-Hz spectral waveform could reveal the geomorphology with parallel-to-wavy seismic reflections (SRCS) for indicating the presence of meandering channels and PBARS. However, this attribute failed to predict the stratigraphic pinch-out zones and exact paleo-inclination of the PBARS and CH. The SLTRS have resolved the parallel-to-wavy SRCS with seismic sedimentological constraints, i.e., lithology-impedance contrast, phase of hydrocarbon generation, tuning frequencies, and thickness of the stratigraphic reservoir configurations, which implicates the channels systems at the shelf position of the basin. These attributes were unable to be predicted using the bandlimited seismic amplitudes. The SLTRS have simulated the gas zone with 2.921 gm. /c.c simulated gas density [SGD], 7880 m/s simulated gas velocity [SGV], 19–25 m simulated gas thickness [SGT], and 1° simulated inclination of PBARS, which implicates the high sinuosity CH and PBARS stratigraphic trap [SAS]. Similarly, for transgressive-to-retrogradation sealing configurations, SLTRS have resolved 2.864 gm. /c.c [SGD], 7365 [m/s] [SGV], 12–14 m simulated seal thickness [SST], and >2° inclination, which implicates the transgressive seal. The vertical and lateral extend of the stratigraphic trap was 16 m (proximal locations) (eastern margins) to 60 m (basin wards) (western margins) of the gas field. The quantitative uncertainty analysis between the SGD [gm. /c.c], SGT [m] and SGV [m/
{"title":"Quantitative appraisal of tectonically-influenced hydrocarbon-bearing Late-Cretaceous fluvial depositional system, Southwest Pakistan using spectral waveform-based instantaneous lateral thickness variability static simulations","authors":"Muhammad Tayyab Naseer","doi":"10.1016/j.jseaes.2024.106377","DOIUrl":"10.1016/j.jseaes.2024.106377","url":null,"abstract":"<div><div>Quantitative seismic reservoir characterization is among the finest advancements in seismic technologies for sub-surface exploration of fluvial depositional systems (FDSS). These FDSS energy resources are combinations of thinly distributed gas-bearing trapping configurations such as the meander sandy channels (CH) along with aggradational parasequences (PBARS) of transgressive system tract (TST), which are developed during the extensive rise of sea-level followed by the rigorous standstill, and hence, which fills the PBARS and CH stratigraphic traps with possible hydrocarbons due to vertical and lateral changes in the facies. These thin-bedded CH and PBARS are very sensitive to a certain frequency component, which bandlimited seismic amplitudes (product of density and velocity) fail to quantify the paleo-thickness, paleo-velocities, paleo-densities, paleo-inclinations, paleo-geomorphology, vertical and lateral extents etc. of the stratigraphic traps. These parameters provide deep insights for quantitative-based stratigraphic reservoir characterizations. This study utilizes the spectral acoustic waveform seismic components and broadband spectrally-decomposed acoustic spectral waveform-based instantaneous lateral thickness variability static simulations (SLTRS) to quantify the FDSS of Southwest Pakistan. The 9–57 Hz bandwidth processed frequency volume reveals a poor tuning frequency component of 28 Hz and lateral extent of the stratigraphic, which failed to predict the direct geomorphology of PBARS and CH. 43-Hz spectral waveform could reveal the geomorphology with parallel-to-wavy seismic reflections (SRCS) for indicating the presence of meandering channels and PBARS. However, this attribute failed to predict the stratigraphic pinch-out zones and exact paleo-inclination of the PBARS and CH. The SLTRS have resolved the parallel-to-wavy SRCS with seismic sedimentological constraints, i.e., lithology-impedance contrast, phase of hydrocarbon generation, tuning frequencies, and thickness of the stratigraphic reservoir configurations, which implicates the channels systems at the shelf position of the basin. These attributes were unable to be predicted using the bandlimited seismic amplitudes. The SLTRS have simulated the gas zone with 2.921 gm. /c.c simulated gas density [SGD], 7880 m/s simulated gas velocity [SGV], 19–25 m simulated gas thickness [SGT], and 1° simulated inclination of PBARS, which implicates the high sinuosity CH and PBARS stratigraphic trap [SAS]. Similarly, for transgressive-to-retrogradation sealing configurations, SLTRS have resolved 2.864 gm. /c.c [SGD], 7365 [m/s] [SGV], 12–14 m simulated seal thickness [SST], and >2° inclination, which implicates the transgressive seal. The vertical and lateral extend of the stratigraphic trap was 16 m (proximal locations) (eastern margins) to 60 m (basin wards) (western margins) of the gas field. The quantitative uncertainty analysis between the SGD [gm. /c.c], SGT [m] and SGV [m/","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"277 ","pages":"Article 106377"},"PeriodicalIF":2.7,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-21DOI: 10.1016/j.jseaes.2024.106378
Shoubiao Zhu
Surface strain rates in southwestern China can provide constraints on tectonic evolution of the Tibetan Plateau. Unfortunately, different strain rate fields were obtained from different authors although almost the same GPS data were exploited. Based on updated GPS data, in this paper, we calculate the strain rates in southwestern China using the method proposed by Zhu et al., 2005, Zhu et al., 2006. The results confirm that the strain rates in the Sichuan Basin and the South China Block are very small, and the high values are largely concentrated along the Xianshuihe-Anninghe-Xiaojiang fault system and the Sagaing Fault. Furthermore, the highest principal strain rates are located around the eastern Himalayan syntaxis (EHS), with compressive orientations perpendicular to the strike of the Main Thrust Belt. The basic characteristic of the strain rate distribution is in accordance with the tectonic structures from the geological and geophysical investigations. In particular, the two calculated extensive deformation regions basically match the locations of normal-faulting earthquakes in the Sichuan-Yunnan Rhombic Block (SYRB), with one in N-S extension trending in the northern SYRB, and the other nearly E-W orientation in the southern SYRB. We suggest that the extensive deformation and the normal faulting earthquakes in southwestern China is mainly controlled by the lower crustal channel flow with a bend direction, rather than by gravitational spreading alone, as previous authors proposed.
{"title":"Contemporary crustal strain rates derived from GPS measurements in southwestern China","authors":"Shoubiao Zhu","doi":"10.1016/j.jseaes.2024.106378","DOIUrl":"10.1016/j.jseaes.2024.106378","url":null,"abstract":"<div><div>Surface strain rates in southwestern China can provide constraints on tectonic evolution of the Tibetan Plateau. Unfortunately, different strain rate fields were obtained from different authors although almost the same GPS data were exploited. Based on updated GPS data, in this paper, we calculate the strain rates in southwestern China using the method proposed by <span><span>Zhu et al., 2005</span></span>, <span><span>Zhu et al., 2006</span></span>. The results confirm that the strain rates in the Sichuan Basin and the South China Block are very small, and the high values are largely concentrated along the Xianshuihe-Anninghe-Xiaojiang fault system and the Sagaing Fault. Furthermore, the highest principal strain rates are located around the eastern Himalayan syntaxis (EHS), with compressive orientations perpendicular to the strike of the Main Thrust Belt. The basic characteristic of the strain rate distribution is in accordance with the tectonic structures from the geological and geophysical investigations. In particular, the two calculated extensive deformation regions basically match the locations of normal-faulting earthquakes in the Sichuan-Yunnan Rhombic Block (SYRB), with one in N-S extension trending in the northern SYRB, and the other nearly E-W orientation in the southern SYRB. We suggest that the extensive deformation and the normal faulting earthquakes in southwestern China is mainly controlled by the lower crustal channel flow with a bend direction, rather than by gravitational spreading alone, as previous authors proposed.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"277 ","pages":"Article 106378"},"PeriodicalIF":2.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-20DOI: 10.1016/j.jseaes.2024.106369
Qingxu Zhao, Mianshui Rong, Jixin Wang, Xiaojun Li
The seismic activity in the north–south seismic belt of China is among the highest in the world. Predicting instrumental intensity and magnitude after an earthquake mitigates regional seismic disasters. The standard workflow for prediction involves building empirical formulas using characteristic parameters of the initial arrival seismic wave, but this method has limitations in accuracy. Recent data-driven models have shown promise in predicting instrument intensity and magnitude. Still, this is currently done mainly on a single-task basis and does not consider whether a multi-task model can utilize complementary information from different tasks to improve overall performance. This study proposes a data-driven multi-task model called SeismNet, which can simultaneously predict instrument intensity and magnitude. We tested the effectiveness of SeismNet using ground motion records of the north–south seismic belt of China. The model can predict instrument intensity and magnitude more rapidly and accurately than the baseline and single-task models, with increasing accuracy as the input seismic wave duration increases. We also tested the method on three destructive earthquake events (Ms > 6.5) that occurred in China and found that at 3 s after the P-wave arrival, the prediction is almost consistent with the observation. Overall, this study offers a new method for improving earthquake prediction accuracy in the North-South seismic belt of China.
{"title":"An end-to-end multi-task network for early prediction of the instrumental intensity and magnitude in the north–south seismic belt of China","authors":"Qingxu Zhao, Mianshui Rong, Jixin Wang, Xiaojun Li","doi":"10.1016/j.jseaes.2024.106369","DOIUrl":"10.1016/j.jseaes.2024.106369","url":null,"abstract":"<div><div>The seismic activity in the north–south seismic belt of China is among the highest in the world. Predicting instrumental intensity and magnitude after an earthquake mitigates regional seismic disasters. The standard workflow for prediction involves building empirical formulas using characteristic parameters of the initial arrival seismic wave, but this method has limitations in accuracy. Recent data-driven models have shown promise in predicting instrument intensity and magnitude. Still, this is currently done mainly on a single-task basis and does not consider whether a multi-task model can utilize complementary information from different tasks to improve overall performance. This study proposes a data-driven multi-task model called SeismNet, which can simultaneously predict instrument intensity and magnitude. We tested the effectiveness of SeismNet using ground motion records of the north–south seismic belt of China. The model can predict instrument intensity and magnitude more rapidly and accurately than the baseline and single-task models, with increasing accuracy as the input seismic wave duration increases. We also tested the method on three destructive earthquake events (Ms > 6.5) that occurred in China and found that at 3 s after the P-wave arrival, the prediction is almost consistent with the observation. Overall, this study offers a new method for improving earthquake prediction accuracy in the North-South seismic belt of China.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"276 ","pages":"Article 106369"},"PeriodicalIF":2.7,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The crust and shallow upper mantle structure beneath the Upper Brahmaputra Valley, Indo-Burma Ranges, and Bengal Basin of Northeast India have been investigated based on receiver function (RF) analysis of teleseismic earthquakes recorded by 11 seismological stations. The study reveals a thin crust (∼35 km) beneath the Brahmaputra Valley (at JORH station) with a surface sedimentary layer of ∼4 km thick. The crustal thickness is observed to increase towards the north in the Himalaya (∼40 km at ZIRO and ITAN) and to the south (up to ∼46 km at KOHI). The crustal thickness near the Tripura fold-belt and Bengal Basin varies within ∼36–40 km. The study reveals the existence of a shallow mantle discontinuity (Hales discontinuity) at a variable depth range of ∼54–78 km characterized by a step increase (∼7.5–11 %) in shear wave velocity observed in the inverted models. The mineralogical phase transformation from spinel to garnet is considered as the origin of this discontinuity. The shallow depth of the discontinuity indicates an increase in upper mantle temperature which conforms to the high geothermal gradient reported in the region. The variation of depth of the discontinuity can be interpreted in terms of the addition of Cr+3 that shifts the spinel-garnet stability field to higher depths whereas Fe+2 shifts it to lower depths. Despite the high temperature in the upper mantle, the observed low Vp/Vs ratio (1.65–1.75) below the Hales discontinuity can be explained by the presence of a high fraction of orthopyroxene.
{"title":"A shallow mantle seismic discontinuity beneath northeast India: Evidence from receiver function analyses","authors":"Devajit Hazarika , Neeharika Shukla , Amlanjyoti Das , Somak Hajra , Sagarika Mukhopadhyay","doi":"10.1016/j.jseaes.2024.106375","DOIUrl":"10.1016/j.jseaes.2024.106375","url":null,"abstract":"<div><div>The crust and shallow upper mantle structure beneath the Upper Brahmaputra Valley, Indo-Burma Ranges, and Bengal Basin of Northeast India have been investigated based on receiver function (RF) analysis of teleseismic earthquakes recorded by 11 seismological stations. The study reveals a thin crust (∼35 km) beneath the Brahmaputra Valley (at JORH station) with a surface sedimentary layer of ∼4 km thick. The crustal thickness is observed to increase towards the north in the Himalaya (∼40 km at ZIRO and ITAN) and to the south (up to ∼46 km at KOHI). The crustal thickness near the Tripura fold-belt and Bengal Basin varies within ∼36–40 km. The study reveals the existence of a shallow mantle discontinuity (Hales discontinuity) at a variable depth range of ∼54–78 km characterized by a step increase (∼7.5–11 %) in shear wave velocity observed in the inverted models. The mineralogical phase transformation from spinel to garnet is considered as the origin of this discontinuity. The shallow depth of the discontinuity indicates an increase in upper mantle temperature which conforms to the high geothermal gradient reported in the region. The variation of depth of the discontinuity can be interpreted in terms of the addition of Cr<sup>+3</sup> that shifts the spinel-garnet stability field to higher depths whereas Fe<sup>+2</sup> shifts it to lower depths. Despite the high temperature in the upper mantle, the observed low Vp/Vs ratio (1.65–1.75) below the Hales discontinuity can be explained by the presence of a high fraction of orthopyroxene.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"276 ","pages":"Article 106375"},"PeriodicalIF":2.7,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-20DOI: 10.1016/j.jseaes.2024.106374
Hongliang Huo , Chenglin Liu , Aibin Zhao , Wenda Li , Rizwan Sarwar Awan , Tao Yi , Zhendong Lu , Qibiao Zang , Dehao Feng , Guoxiong Li , Jiajia Su
Lacustrine gravity-flow tight sandstone reservoirs are rich in petroleum resources, and the presence of movable fluids is essential for the efficient recovery of tight oil. However, characterizing the properties of movable fluids and predicting their content are challenging due to the limited data available on these fluids. To address this research gap, it is imperative to conduct a comprehensive study on the distribution patterns and controlling factors of movable fluids within the lacustrine gravity-flow tight sandstone reservoirs of the Chang-7 Member in the Heshui region of the Ordos Basin. The study utilized a range of analytical techniques, such as thin section analysis, scanning electron microscopy (SEM), high-pressure mercury injection (HPMI), constant-rate mercury injection (CRMI), and nuclear magnetic resonance (NMR). We identified three distinct lithofacies and three types of pore-throat spaces within these lacustrine gravity-flow sandstones. The highest amount of movable fluid was observed in the submicron pore throats, followed by nanopore throats, while the micron pore throats exhibited the lowest amount. Our analysis indicates that petrophysical parameters, mineral composition, and pore throat structures collectively influence the content of movable fluids. Specifically, quartz and feldspar content are positively correlated with the movable fluid content, while clay and carbonate cement content are negatively correlated. Fine sandstones with massive bedding typically have a high content of movable fluids, which is associated with elevated quartz and feldspar content. In contrast, very fine sandstones to siltstones with parallel or ripple beddings have a very low content of movable fluids, characterized by high levels of carbonate and clay cementation. The study also suggests that the lower limit of the pore throat radius of movable fluid is about 0.03 μm. These findings offer novel insights for evaluating and predicting high-quality lacustrine gravity-flow tight sandstone reservoirs, enabling more effective exploration and development strategies.
{"title":"Evaluation of movable fluid and controlling factors in lacustrine gravity-flow tight sandstone reservoirs: Implications for predicting reservoir quality","authors":"Hongliang Huo , Chenglin Liu , Aibin Zhao , Wenda Li , Rizwan Sarwar Awan , Tao Yi , Zhendong Lu , Qibiao Zang , Dehao Feng , Guoxiong Li , Jiajia Su","doi":"10.1016/j.jseaes.2024.106374","DOIUrl":"10.1016/j.jseaes.2024.106374","url":null,"abstract":"<div><div>Lacustrine gravity-flow tight sandstone reservoirs are rich in petroleum resources, and the presence of movable fluids is essential for the efficient recovery of tight oil. However, characterizing the properties of movable fluids and predicting their content are challenging due to the limited data available on these fluids. To address this research gap, it is imperative to conduct a comprehensive study on the distribution patterns and controlling factors of movable fluids within the lacustrine gravity-flow tight sandstone reservoirs of the Chang-7 Member in the Heshui region of the Ordos Basin. The study utilized a range of analytical techniques, such as thin section analysis, scanning electron microscopy (SEM), high-pressure mercury injection (HPMI), constant-rate mercury injection (CRMI), and nuclear magnetic resonance (NMR). We identified three distinct lithofacies and three types of pore-throat spaces within these lacustrine gravity-flow sandstones. The highest amount of movable fluid was observed in the submicron pore throats, followed by nanopore throats, while the micron pore throats exhibited the lowest amount. Our analysis indicates that petrophysical parameters, mineral composition, and pore throat structures collectively influence the content of movable fluids. Specifically, quartz and feldspar content are positively correlated with the movable fluid content, while clay and carbonate cement content are negatively correlated. Fine sandstones with massive bedding typically have a high content of movable fluids, which is associated with elevated quartz and feldspar content. In contrast, very fine sandstones to siltstones with parallel or ripple beddings have a very low content of movable fluids, characterized by high levels of carbonate and clay cementation. The study also suggests that the lower limit of the pore throat radius of movable fluid is about 0.03 μm. These findings offer novel insights for evaluating and predicting high-quality lacustrine gravity-flow tight sandstone reservoirs, enabling more effective exploration and development strategies.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"277 ","pages":"Article 106374"},"PeriodicalIF":2.7,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-20DOI: 10.1016/j.jseaes.2024.106370
Weihua Wu , Werner Nel , Junfeng Ji , Jun Chen
The carbon sink effect of afforestation is key to mitigating current global warming. China’s planted forest area accounts for more than a quarter of the global afforestation efforts and has made a prominent contribution to carbon sequestration. Previously, afforestation as a carbon sink was primarily evaluated in terms of the biomass carbon pool and soil organic carbon pool. Plants play a significant role in enhancing the chemical weathering of rocks and minerals, which can lead to more CO2 consumption. However, role of plants in enhancing chemical weathering and contributing to CO2 removal has not been considered when calculating the artificial sink. This paper reviews relevant studies on the carbon sinks from weathering and forest biomass in China and synthesizes the research on how plants affecting weathering in natural ecosystems. Based on this, we estimate the atmospheric CO2 consumption from afforestation-enhanced weathering in China. If afforestation increases the natural weathering rate by a factor of four on average, the national carbon sink through weathering could increase by 33 %. This increase in carbon sink capacity amounts to 35 million tonnes CO2/y and represents ∼1/6 of China’s afforestation biomass carbon sink during 2014–2018. The significant contribution underscores the need for further comprehensive research into the carbon sink effect of afforestation-enhanced weathering in the future. Understanding how afforestation, global warming, and other anthropogenic activities interact to affect weathering will provide insights to accurately evaluate the role of large-scale afforestation in China’s efforts to meet its “dual-carbon” goals and mitigate global warming.
{"title":"Prospects for the potential carbon sink effects of afforestation to enhance weathering in China","authors":"Weihua Wu , Werner Nel , Junfeng Ji , Jun Chen","doi":"10.1016/j.jseaes.2024.106370","DOIUrl":"10.1016/j.jseaes.2024.106370","url":null,"abstract":"<div><div>The carbon sink effect of afforestation is key to mitigating current global warming. China’s planted forest area accounts for more than a quarter of the global afforestation efforts and has made a prominent contribution to carbon sequestration. Previously, afforestation as a carbon sink was primarily evaluated in terms of the biomass carbon pool and soil organic carbon pool. Plants play a significant role in enhancing the chemical weathering of rocks and minerals, which can lead to more CO<sub>2</sub> consumption. However, role of plants in enhancing chemical weathering and contributing to CO<sub>2</sub> removal has not been considered when calculating the artificial sink. This paper reviews relevant studies on the carbon sinks from weathering and forest biomass in China and synthesizes the research on how plants affecting weathering in natural ecosystems. Based on this, we estimate the atmospheric CO<sub>2</sub> consumption from afforestation-enhanced weathering in China. If afforestation increases the natural weathering rate by a factor of four on average, the national carbon sink through weathering could increase by 33 %. This increase in carbon sink capacity amounts to 35 million tonnes CO<sub>2</sub>/y and represents ∼1/6 of China’s afforestation biomass carbon sink during 2014–2018. The significant contribution underscores the need for further comprehensive research into the carbon sink effect of afforestation-enhanced weathering in the future. Understanding how afforestation, global warming, and other anthropogenic activities interact to affect weathering will provide insights to accurately evaluate the role of large-scale afforestation in China’s efforts to meet its “dual-carbon” goals and mitigate global warming.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"276 ","pages":"Article 106370"},"PeriodicalIF":2.7,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-20DOI: 10.1016/j.jseaes.2024.106372
Xian-Gang Xie , Maoliang Zhang , Wei Liu , Yi Liu , Linan Wang , Yunchao Lang , Sheng Xu
Strike-slip faults play a significant role in creating deeply penetrating fractures with high permeability, thus promoting rapid migration of CO2-rich fluids to the surface. However, there are rare observations regarding how strike-slip movement could affect deep CO2 emissions. Here, we focus on the Karakoram fault system (KKFS), western Tibet, to estimate diffuse soil CO2 fluxes and to unravel potential controlling factors for CO2 emissions. Average CO2 fluxes of geothermal fields range in 22–2475 g m−2 d−1, significantly higher than the across-fault profiles (6–116 g m−2 d−1). A mass balance model based on δ13C-CO2 and CO2 concentration of soil gases reveals that deep carbon constitutes 49.1–91.5 % (average = 73.9 %) and 0.2–40.5 % (average = 25.5 %) of soil-gas carbon released from geothermal fields and across-fault profiles, respectively. Deep carbon could be produced by thermal decomposition of crustal rocks considering CO2-rich fluids with radiogenic helium isotopes. Strikingly, higher CO2 fluxes preferentially occur in geothermal fields along a bending segment of the KKFS, where localized shear deformation is prominent as documented by high slip rates over geological timescales, dense splay faults, clustering of earthquake events, and elevated strain rates. We suggest that high stress acting on the KKFS bend could enhance the deformation and fracturing of fault zone rocks, leading to production of metamorphic CO2 and efficient release of CO2-rich fluids through the highly permeable fault system. Our results could shed new light on CO2 origins and fluxes of strike-slip faults that are characterized by spatially heterogeneous strain partitioning and thus localized enhanced shear deformation.
走向滑动断层在形成具有高渗透性的深穿透裂缝方面发挥着重要作用，从而促进富含二氧化碳的流体快速迁移到地表。然而，有关走向滑动如何影响深层二氧化碳排放的观测却很少见。在此，我们以西藏西部的喀喇昆仑断层系统（KKFS）为研究对象，估算土壤中弥散的二氧化碳通量，并揭示二氧化碳排放的潜在控制因素。地热田的平均二氧化碳通量介于 22-2475 g m-2 d-1 之间，明显高于跨断层剖面（6-116 g m-2 d-1）。基于δ13C-CO2 和土壤气体二氧化碳浓度的质量平衡模型显示，深层碳分别占地热田和跨断层剖面释放的土壤气体碳的 49.1-91.5%（平均 = 73.9%）和 0.2-40.5%（平均 = 25.5%）。深层碳可能是由地壳岩石热分解产生的，考虑到富含二氧化碳的流体具有放射性氦同位素。令人震惊的是，较高的二氧化碳通量优先出现在KKFS弯曲段沿线的地热田中，地质时间尺度上的高滑动率、密集的飞溅断层、地震事件的集群以及较高的应变率都证明了这里局部剪切变形的显著性。我们认为，作用于 KKFS 弯道的高应力可能会增强断层带岩石的变形和断裂，导致变质二氧化碳的产生，并通过高渗透性断层系统有效释放富含二氧化碳的流体。我们的研究结果可以为研究具有空间异质应变分区特征的走向滑动断层的二氧化碳来源和通量提供新的视角，这些断层具有局部剪切变形增强的特征。
{"title":"Deep CO2 emissions facilitated by localized shear deformation: A case study of the Karakoram fault system, western Tibet","authors":"Xian-Gang Xie , Maoliang Zhang , Wei Liu , Yi Liu , Linan Wang , Yunchao Lang , Sheng Xu","doi":"10.1016/j.jseaes.2024.106372","DOIUrl":"10.1016/j.jseaes.2024.106372","url":null,"abstract":"<div><div>Strike-slip faults play a significant role in creating deeply penetrating fractures with high permeability, thus promoting rapid migration of CO<sub>2</sub>-rich fluids to the surface. However, there are rare observations regarding how strike-slip movement could affect deep CO<sub>2</sub> emissions. Here, we focus on the Karakoram fault system (KKFS), western Tibet, to estimate diffuse soil CO<sub>2</sub> fluxes and to unravel potential controlling factors for CO<sub>2</sub> emissions. Average CO<sub>2</sub> fluxes of geothermal fields range in 22–2475 g m<sup>−2</sup> d<sup>−1</sup>, significantly higher than the across-fault profiles (6–116 g m<sup>−2</sup> d<sup>−1</sup>). A mass balance model based on δ<sup>13</sup>C-CO<sub>2</sub> and CO<sub>2</sub> concentration of soil gases reveals that deep carbon constitutes 49.1–91.5 % (average = 73.9 %) and 0.2–40.5 % (average = 25.5 %) of soil-gas carbon released from geothermal fields and across-fault profiles, respectively. Deep carbon could be produced by thermal decomposition of crustal rocks considering CO<sub>2</sub>-rich fluids with radiogenic helium isotopes. Strikingly, higher CO<sub>2</sub> fluxes preferentially occur in geothermal fields along a bending segment of the KKFS, where localized shear deformation is prominent as documented by high slip rates over geological timescales, dense splay faults, clustering of earthquake events, and elevated strain rates. We suggest that high stress acting on the KKFS bend could enhance the deformation and fracturing of fault zone rocks, leading to production of metamorphic CO<sub>2</sub> and efficient release of CO<sub>2</sub>-rich fluids through the highly permeable fault system. Our results could shed new light on CO<sub>2</sub> origins and fluxes of strike-slip faults that are characterized by spatially heterogeneous strain partitioning and thus localized enhanced shear deformation.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"277 ","pages":"Article 106372"},"PeriodicalIF":2.7,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding the mechanisms and locations of interseismic strain accumulation along faults is essential for assessing earthquake hazards. However, the mechanical response during the transition from deep fault locking to creep behavior remains uncertain. Estimating the slip deficit within these transition zones is challenging. This study challenges the assumption of a constant depth distribution of interseismic slip rate along the fault over time and proposes variable locking depths as an alternative model. By rejecting the constant locking depth assumption, singularity issues during stress theorem resolution are resolved. To address this, we employ a methodology considering creep propagation within a fully elastic medium. This approach incorporates long-term deformation resulting from viscoelastic flow in the upper mantle and lower crust. Including viscoelastic effects improves the fit to interseismic deformation rates, yielding lower locking depths compared to fully elastic models. To conduct the investigation, the GPS velocity field is recovered using the forward problem and the boundary element method. Subsequently, a physics-based inversion approach, deep interseismic creep, is employed to determine interseismic deformation patterns on a strike-slip fault. Furthermore, this study examined the correlation between the dislocation parameters and their relationship, as well as established the probability distributions associated with each faulting parameter. This research highlights the importance of considering variable locking depths in understanding interseismic strain accumulation and the transition to creep behavior along faults. The findings contribute to improved earthquake hazard assessment and mitigation strategies by providing valuable insights into fault behavior mechanics along the North Tabriz Fault.
{"title":"Evaluating interseismic deformation patterns in the North Tabriz Fault (Iran) using enhanced fitting of velocity field and analysis of surface deformation","authors":"Milad Salmanian , Asghar Rastbood , Masoud Mashhadi Hossainali","doi":"10.1016/j.jseaes.2024.106376","DOIUrl":"10.1016/j.jseaes.2024.106376","url":null,"abstract":"<div><div>Understanding the mechanisms and locations of interseismic strain accumulation along faults is essential for assessing earthquake hazards. However, the mechanical response during the transition from deep fault locking to creep behavior remains uncertain. Estimating the slip deficit within these transition zones is challenging. This study challenges the assumption of a constant depth distribution of interseismic slip rate along the fault over time and proposes variable locking depths as an alternative model. By rejecting the constant locking depth assumption, singularity issues during stress theorem resolution are resolved. To address this, we employ a methodology considering creep propagation within a fully elastic medium. This approach incorporates long-term deformation resulting from viscoelastic flow in the upper mantle and lower crust. Including viscoelastic effects improves the fit to interseismic deformation rates, yielding lower locking depths compared to fully elastic models. To conduct the investigation, the GPS velocity field is recovered using the forward problem and the boundary element method. Subsequently, a physics-based inversion approach, deep interseismic creep, is employed to determine interseismic deformation patterns on a strike-slip fault. Furthermore, this study examined the correlation between the dislocation parameters and their relationship, as well as established the probability distributions associated with each faulting parameter. This research highlights the importance of considering variable locking depths in understanding interseismic strain accumulation and the transition to creep behavior along faults. The findings contribute to improved earthquake hazard assessment and mitigation strategies by providing valuable insights into fault behavior mechanics along the North Tabriz Fault.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"277 ","pages":"Article 106376"},"PeriodicalIF":2.7,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-20DOI: 10.1016/j.jseaes.2024.106366
Jin-zhi Ma , Zhuowei Xiao , Long Li , Yinshuang Ai
The Daliangshan block is located between the Tibetan Plateau and the South China block and has accommodated several M > 6.5 damaging earthquakes in the past ∼600 years, as well as intense tectonic deformation and complex fault structures. In this study, we analyze more than two years of continuous seismic data recorded by a recently deployed dense seismic array. We used a recently developed machine learning-based earthquake location workflow (ESPRH) to construct a high-precision earthquake catalog for the region and obtained 3539 earthquakes, which is approximately three times as many as the National Earthquake Data Center (NEDC) catalog contains. The seismicity distribution not only confirms the nature of the faults marked on the map but also delineates the detailed geometry of the unmapped faults, including the en échelon faults at the northern end of the Zemuhe Fault and the “V”-shaped conjugate fault within the Mabian Fault Zone. The Zemuhe Fault and Lianfeng Fault are prone to hosting large earthquakes according to the derived low b-value. The western side of the Daliangshan block is dominated by strike-slip faults. Combining the fault geometry presented in this paper, we observed that the fault properties on the eastern side are complex. This tectonic phenomenon is attributed to the fact that during the lateral extrusion of the southeastern edge of the Chuandian fragments, the northeastern part of the Daliangshan block was squeezed by the South China block more strongly than its southwestern part. We provide the first precise earthquake catalog for Daliangshan block, which can be used as important seismological data for regional hazard assessment and research on the southeastern (SE) margin of the Tibetan Plateau.
大凉山地块位于青藏高原和华南地块之间，在过去的 600 多年里曾发生过多次 M > 6.5 级破坏性地震，并伴有强烈的构造变形和复杂的断层结构。在本研究中，我们分析了最近部署的密集地震阵列记录的两年多连续地震数据。我们利用最近开发的基于机器学习的地震定位工作流程（ESPRH）构建了该地区的高精度地震目录，获得了 3539 次地震，约为国家地震数据中心（NEDC）地震目录所含地震次数的三倍。地震分布不仅证实了地图上标注的断层的性质，还勾勒出了未绘制地图的断层的详细几何形状，包括泽木河断层北端的梯形断层和马边断层带内的 "V "形共轭断层。根据得出的低 b 值，则木河断层和莲峰断层容易发生大地震。大凉山地块西侧以走向滑动断层为主。结合本文提出的断层几何特征，我们观察到东侧的断层性质比较复杂。这种构造现象是由于在川地碎块东南边缘横向挤压过程中，大凉山地块东北部受到华南地块的挤压比其西南部更为强烈。我们首次提供了大凉山区块的精确地震目录，可作为青藏高原东南缘区域灾害评估和研究的重要地震学数据。
{"title":"Microseismicity and fault structure in the Daliangshan block within the Southeastern Tibetan Plateau","authors":"Jin-zhi Ma , Zhuowei Xiao , Long Li , Yinshuang Ai","doi":"10.1016/j.jseaes.2024.106366","DOIUrl":"10.1016/j.jseaes.2024.106366","url":null,"abstract":"<div><div>The Daliangshan block is located between the Tibetan Plateau and the South China block and has accommodated several M > 6.5 damaging earthquakes in the past ∼600 years, as well as intense tectonic deformation and complex fault structures. In this study, we analyze more than two years of continuous seismic data recorded by a recently deployed dense seismic array. We used a recently developed machine learning-based earthquake location workflow (ESPRH) to construct a high-precision earthquake catalog for the region and obtained 3539 earthquakes, which is approximately three times as many as the National Earthquake Data Center (NEDC) catalog contains. The seismicity distribution not only confirms the nature of the faults marked on the map but also delineates the detailed geometry of the unmapped faults, including the en échelon faults at the northern end of the Zemuhe Fault and the “V”-shaped conjugate fault within the Mabian Fault Zone. The Zemuhe Fault and Lianfeng Fault are prone to hosting large earthquakes according to the derived low b-value. The western side of the Daliangshan block is dominated by strike-slip faults. Combining the fault geometry presented in this paper, we observed that the fault properties on the eastern side are complex. This tectonic phenomenon is attributed to the fact that during the lateral extrusion of the southeastern edge of the Chuandian fragments, the northeastern part of the Daliangshan block was squeezed by the South China block more strongly than its southwestern part. We provide the first precise earthquake catalog for Daliangshan block, which can be used as important seismological data for regional hazard assessment and research on the southeastern (SE) margin of the Tibetan Plateau.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"276 ","pages":"Article 106366"},"PeriodicalIF":2.7,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-19DOI: 10.1016/j.jseaes.2024.106371
Zhishun Zhang , Guanglu Zhang , Yanyan Zhao , Chenhui Liu , Sheng Liu , Jun Yang , Xiaoqiang Guo , Haotian Wei , Sanzhong Li
The delivery of bioavailable iron (Fe) to the marine environment has important implications for marine biogeochemical cycling. However, only limited studies have explored the transportation and transformation of sediment Fe in oxic open marginal seas. In this study, we compiled and analyzed newly measured and published Fe speciation data for sediments in the northern South China Sea. The expected FeT/Al ratio of marine sediment calculated from river discharge is consistent with the measured one. This indicates limited estuarine trap removal occurred during the seaward input of riverine particulate Fe. However, the proportion of Fe oxides within the total Fe pool (Feox/FeT) in offshore sediments (0.28 ± 0.03) is lower than that in source river particulates (>0.38). We propose that the transformation of Fe oxides into authigenic Fe-bearing clay minerals during reverse weathering may be the best explanation. Furthermore, the Feox/FeT ratios in sediments increase from shelf to basin and have a good positive correlation with the contents of fine-grained fraction (<4 μm). We argue that this redistribution of reactive Fe oxides from shelf to basin is mainly controlled by physical shuttle (sorting). In addition, the Fe speciation of deep (>50 cmbsf) sediments in the northern South China Sea is influenced by diagenesis. We conclude that, unlike the low-O2 continental margins, the oxic northern South China Sea mainly serves as an Fe sink.
{"title":"Transportation and transformation of sedimentary Fe speciation in the northern South China Sea","authors":"Zhishun Zhang , Guanglu Zhang , Yanyan Zhao , Chenhui Liu , Sheng Liu , Jun Yang , Xiaoqiang Guo , Haotian Wei , Sanzhong Li","doi":"10.1016/j.jseaes.2024.106371","DOIUrl":"10.1016/j.jseaes.2024.106371","url":null,"abstract":"<div><div>The delivery of bioavailable iron (Fe) to the marine environment has important implications for marine biogeochemical cycling. However, only limited studies have explored the transportation and transformation of sediment Fe in oxic open marginal seas. In this study, we compiled and analyzed newly measured and published Fe speciation data for sediments in the northern South China Sea. The expected Fe<sub>T</sub>/Al ratio of marine sediment calculated from river discharge is consistent with the measured one. This indicates limited estuarine trap removal occurred during the seaward input of riverine particulate Fe. However, the proportion of Fe oxides within the total Fe pool (Fe<sub>ox</sub>/Fe<sub>T</sub>) in offshore sediments (0.28 ± 0.03) is lower than that in source river particulates (>0.38). We propose that the transformation of Fe oxides into authigenic Fe-bearing clay minerals during reverse weathering may be the best explanation. Furthermore, the Fe<sub>ox</sub>/Fe<sub>T</sub> ratios in sediments increase from shelf to basin and have a good positive correlation with the contents of fine-grained fraction (<4 μm). We argue that this redistribution of reactive Fe oxides from shelf to basin is mainly controlled by physical shuttle (sorting). In addition, the Fe speciation of deep (>50 cmbsf) sediments in the northern South China Sea is influenced by diagenesis. We conclude that, unlike the low-O<sub>2</sub> continental margins, the oxic northern South China Sea mainly serves as an Fe sink.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"276 ","pages":"Article 106371"},"PeriodicalIF":2.7,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：