Boo‐Keun Khim, Young Kwan Sohn, Min Kyung Lee, Sunghan Kim, Jae Il Lee, Kyu Cheul Yoo
Abstract Glaciomarine laminated muds around the Antarctic continental margin are important in the marine geological record related to ice sheet dynamics. Microscopic observation and backscattered electron imagery of Pleistocene laminated muds in the Central Basin (Ross Sea) reveal that the light laminae comprise terrigenous angular to subangular silt‐sized particles, scattered diatom fragments, and eroded sand‐sized lumps of fossil‐bearing mud. In contrast, the dark laminae are clayey and biogenic with very tiny pieces of fossils. These laminated muds are interpreted to have been deposited by subglacial meltwater plumes underneath the advancing glaciers that torn off the earlier‐deposited and semi‐consolidated diatom‐rich sediments. Thus, most biogenic components of these laminated muds were recycled from older deposits, indicating that they are not related to enhanced biological production during the mud deposition. Our study suggests that the recycling of biogenic particles should be considered when interpreting the palaeoclimatic and palaeoceanographic implications of Antarctic environmental system.
{"title":"Pleistocene glaciomarine laminated muds in the Central Basin of the northwestern Ross Sea and their palaeoceanographic records","authors":"Boo‐Keun Khim, Young Kwan Sohn, Min Kyung Lee, Sunghan Kim, Jae Il Lee, Kyu Cheul Yoo","doi":"10.1111/ter.12688","DOIUrl":"https://doi.org/10.1111/ter.12688","url":null,"abstract":"Abstract Glaciomarine laminated muds around the Antarctic continental margin are important in the marine geological record related to ice sheet dynamics. Microscopic observation and backscattered electron imagery of Pleistocene laminated muds in the Central Basin (Ross Sea) reveal that the light laminae comprise terrigenous angular to subangular silt‐sized particles, scattered diatom fragments, and eroded sand‐sized lumps of fossil‐bearing mud. In contrast, the dark laminae are clayey and biogenic with very tiny pieces of fossils. These laminated muds are interpreted to have been deposited by subglacial meltwater plumes underneath the advancing glaciers that torn off the earlier‐deposited and semi‐consolidated diatom‐rich sediments. Thus, most biogenic components of these laminated muds were recycled from older deposits, indicating that they are not related to enhanced biological production during the mud deposition. Our study suggests that the recycling of biogenic particles should be considered when interpreting the palaeoclimatic and palaeoceanographic implications of Antarctic environmental system.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"123 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135570231","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}
Pauline Chenin, Simon Tomasi, Nick Kusznir, Gianreto Manatschal
Abstract Determining the volume and timing of magmatism during rifting and breakup is challenging due to the similar density and seismic velocity of inherited continental crust, magmatic additions and serpentinized mantle; and the difficulty of dating magmatic additions. Here rules of thumb to estimate these are proposed based on the characteristics of the top basement and Moho on seismically imaged margins. A simple kinematic model is used to generate first‐order crustal shapes of margins as a function of magma volume and timing of emplacement, which are successfully compared to a representative number of rifted margins. It appears that ‘magma‐rich margins’ require melt emplacement in advance of crustal thinning but not necessarily enhanced melt volume, while margins with exhumed mantle require a delay in melt emplacement but not necessarily a low magmatic volume. An alternative classification for the magma‐poor/magma‐rich dichotomy is proposed to better represent the crustal shape variability of rifted margins.
{"title":"Linking rifted margin crustal shape with the timing and volume of magmatism","authors":"Pauline Chenin, Simon Tomasi, Nick Kusznir, Gianreto Manatschal","doi":"10.1111/ter.12690","DOIUrl":"https://doi.org/10.1111/ter.12690","url":null,"abstract":"Abstract Determining the volume and timing of magmatism during rifting and breakup is challenging due to the similar density and seismic velocity of inherited continental crust, magmatic additions and serpentinized mantle; and the difficulty of dating magmatic additions. Here rules of thumb to estimate these are proposed based on the characteristics of the top basement and Moho on seismically imaged margins. A simple kinematic model is used to generate first‐order crustal shapes of margins as a function of magma volume and timing of emplacement, which are successfully compared to a representative number of rifted margins. It appears that ‘magma‐rich margins’ require melt emplacement in advance of crustal thinning but not necessarily enhanced melt volume, while margins with exhumed mantle require a delay in melt emplacement but not necessarily a low magmatic volume. An alternative classification for the magma‐poor/magma‐rich dichotomy is proposed to better represent the crustal shape variability of rifted margins.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135858792","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}
Kurt E. Sundell, Andrew K. Laskowski, Caden Howlett, Paul Kapp, Mihai Ducea, James B. Chapman, Lin Ding
Abstract Recent advancements in quantitatively estimating the thickness of Earth's crust in the geologic past provide an opportunity to test hypotheses explaining the tectonic evolution of southern Tibet. Outstanding debate on southern Tibet's Cenozoic geological evolution is complicated by poorly understood Mesozoic tectonics. We present new U‐Pb geochronology and trace element chemistry of detrital zircon from modern rivers draining the Gangdese Mountains in southern Tibet. Results are similar to recently published quantitative estimates of crustal thickness derived from intermediate‐composition whole rock records and show ~30 km of crustal thinning from 90 to 70 Ma followed by thickening to near‐modern values from 70 to 40 Ma. These results extend evidence of Late Cretaceous north–south extension along strike to the west by ~200 km, and support a tectonic model in which an east–west striking back‐arc basin formed along Eurasia's southern margin during slab rollback, prior to terminal collision of India with Eurasia.
{"title":"Episodic Late Cretaceous to Neogene crustal thickness variation in southern Tibet","authors":"Kurt E. Sundell, Andrew K. Laskowski, Caden Howlett, Paul Kapp, Mihai Ducea, James B. Chapman, Lin Ding","doi":"10.1111/ter.12689","DOIUrl":"https://doi.org/10.1111/ter.12689","url":null,"abstract":"Abstract Recent advancements in quantitatively estimating the thickness of Earth's crust in the geologic past provide an opportunity to test hypotheses explaining the tectonic evolution of southern Tibet. Outstanding debate on southern Tibet's Cenozoic geological evolution is complicated by poorly understood Mesozoic tectonics. We present new U‐Pb geochronology and trace element chemistry of detrital zircon from modern rivers draining the Gangdese Mountains in southern Tibet. Results are similar to recently published quantitative estimates of crustal thickness derived from intermediate‐composition whole rock records and show ~30 km of crustal thinning from 90 to 70 Ma followed by thickening to near‐modern values from 70 to 40 Ma. These results extend evidence of Late Cretaceous north–south extension along strike to the west by ~200 km, and support a tectonic model in which an east–west striking back‐arc basin formed along Eurasia's southern margin during slab rollback, prior to terminal collision of India with Eurasia.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013210","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}
Abstract Records of the Lomagundi–Jatuli Event (LJE) are well preserved globally, but high δ 13 C carb carbonates have not been identified in the North China Craton (NCC). Our results on ~ 3–4 km thick carbonates from the newly confirmed Palaeoproterozoic successions in Fanhe Basin in the northeastern NCC show that the ~2.20–2.06 Ga carbonates have positive carbon isotope excursion and those deposited after 2.06 Ga have normal carbon isotope. Specially, carbonates from the Daposhan Formation have δ 13 C carb values of 10.2‰–11.8‰, which is the largest positive carbon isotope excursion in the NCC. The ~2.20–2.06 Ga carbonates in Fanhe Basin have similar δ 13 C carb values as those contemporaneously deposited in other cratons and their δ 13 C carb values exhibit a decreasing trend from ~2.20 Ga to 2.06 Ga. Our identification of carbonates with high positive δ 13 C carb values in Fanhe Basin not only casts new lights on records of the LJE in the NCC, but also provides important constraints on global significance of the positive δ 13 C carb excursion of LJE.
{"title":"High positive carbonate carbon isotope excursion identified in the North China Craton: Implications for the <scp>Lomagundi–Jatuli</scp> Event","authors":"Shuan‐Hong Zhang, Hong‐Yu Wang, Hao‐Shu Tang, Yu‐Hang Cai, Ling‐Hao Kong, Jun‐Ling Pei, Qi‐Qi Zhang, Guo‐Hui Hu, Yue Zhao","doi":"10.1111/ter.12687","DOIUrl":"https://doi.org/10.1111/ter.12687","url":null,"abstract":"Abstract Records of the Lomagundi–Jatuli Event (LJE) are well preserved globally, but high δ 13 C carb carbonates have not been identified in the North China Craton (NCC). Our results on ~ 3–4 km thick carbonates from the newly confirmed Palaeoproterozoic successions in Fanhe Basin in the northeastern NCC show that the ~2.20–2.06 Ga carbonates have positive carbon isotope excursion and those deposited after 2.06 Ga have normal carbon isotope. Specially, carbonates from the Daposhan Formation have δ 13 C carb values of 10.2‰–11.8‰, which is the largest positive carbon isotope excursion in the NCC. The ~2.20–2.06 Ga carbonates in Fanhe Basin have similar δ 13 C carb values as those contemporaneously deposited in other cratons and their δ 13 C carb values exhibit a decreasing trend from ~2.20 Ga to 2.06 Ga. Our identification of carbonates with high positive δ 13 C carb values in Fanhe Basin not only casts new lights on records of the LJE in the NCC, but also provides important constraints on global significance of the positive δ 13 C carb excursion of LJE.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135482853","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}
Abstract This study delves into the interplay of Rayleigh wave‐groundwater‐aquifer dynamics, utilizing seismic data from designated stations, particularly the magnitude 9 event on March 11, 2011 (02:46:23 PM epicenter), Tohoku earthquake, Japan. Auto spectra uncover significant peaks, linking groundwater level with the vertical motion of Rayleigh waves. High coherence between groundwater levels and seismogram vertical displacements confirms this connection. Coherence analysis validates it at the significant frequency bands. Groundwater storage coefficient estimation aligns with typical values of confined aquifers, ranging from 1.0E‐05 to 1.0E‐03. This consistency applies across different methods and other earthquake events, highlighting seismic impact. The findings enhance understanding of aquifer behavior during seismic events, aiding groundwater management and earthquake readiness in susceptible regions. Further research should expand datasets for coefficient accuracy. Insights advance aquifer behavior comprehension during seismic events, guiding groundwater management and earthquake readiness in prone areas.
{"title":"Storage in the deep aquifer: Stochastic process in time and frequency domain using groundwater level response to seismic activation of the Tohoku earthquake, Japan, 2011","authors":"David Ching‐Fang Shih","doi":"10.1111/ter.12686","DOIUrl":"https://doi.org/10.1111/ter.12686","url":null,"abstract":"Abstract This study delves into the interplay of Rayleigh wave‐groundwater‐aquifer dynamics, utilizing seismic data from designated stations, particularly the magnitude 9 event on March 11, 2011 (02:46:23 PM epicenter), Tohoku earthquake, Japan. Auto spectra uncover significant peaks, linking groundwater level with the vertical motion of Rayleigh waves. High coherence between groundwater levels and seismogram vertical displacements confirms this connection. Coherence analysis validates it at the significant frequency bands. Groundwater storage coefficient estimation aligns with typical values of confined aquifers, ranging from 1.0E‐05 to 1.0E‐03. This consistency applies across different methods and other earthquake events, highlighting seismic impact. The findings enhance understanding of aquifer behavior during seismic events, aiding groundwater management and earthquake readiness in susceptible regions. Further research should expand datasets for coefficient accuracy. Insights advance aquifer behavior comprehension during seismic events, guiding groundwater management and earthquake readiness in prone areas.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135739576","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}
Abstract This paper draws attention to the contribution of tidal friction (TF) to plate tectonic processes. Our proposed model supports recent geodetic observations and geodynamic models highlighting exogenous local contributions to plate motions. The TF has a westward effect on lithospheric plates and the lithosphere as a whole. To determine the extent of this effect, we use the asthenospheric viscosity estimated using the Eötvös force. We also show that TF has a detectable impact on the latitudinal distribution of earthquake activity.
{"title":"Impact of tidal friction on the motion of lithospheric plates and earthquake activity","authors":"Csilla Fodor, Péter Varga, Nico Sneeuw","doi":"10.1111/ter.12685","DOIUrl":"https://doi.org/10.1111/ter.12685","url":null,"abstract":"Abstract This paper draws attention to the contribution of tidal friction (TF) to plate tectonic processes. Our proposed model supports recent geodetic observations and geodynamic models highlighting exogenous local contributions to plate motions. The TF has a westward effect on lithospheric plates and the lithosphere as a whole. To determine the extent of this effect, we use the asthenospheric viscosity estimated using the Eötvös force. We also show that TF has a detectable impact on the latitudinal distribution of earthquake activity.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"132 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135247755","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}
Nan Wang, Zhiyong Zhang, Marco G. Malusà, Jien Zhang, Lin Wu, Dunfeng Xiang, Wenjiao Xiao
Abstract The impact of tectonics, volcanism and climate in controlling temporal and spatial variations in rift‐basin sedimentation is still poorly understood. Here, we tackle this issue by the analysis of mid‐Cretaceous sediments deposited in the Songliao Basin, northeastern China. We present new zircon U–Pb, apatite fission‐track and trace‐element data from the northeastern basin, which are discussed within the framework of the published geochronology dataset. Our results reveal a major provenance change from syn‐rift tectonic extension to post‐rift thermal subsidence at ~103 Ma. During the syn‐rift stage, the detrital inputs were dominantly from transverse rivers sourced from the surrounding mountains including graben shoulders and volcanoes. During the post‐rift stage and coeval thermal subsidence, the basin sedimentation was controlled by coexisting transverse and axial drainage systems sourced from uplifting regions in the south. We conclude that tectonics, not climate, exerted a major control in sediment provenance change in the mid‐Cretaceous Songliao Basin.
{"title":"Geo‐thermochronological analysis reveals transition from transverse to axial detrital inputs during Cretaceous rifting in the Songliao Basin, <scp>NE</scp> China","authors":"Nan Wang, Zhiyong Zhang, Marco G. Malusà, Jien Zhang, Lin Wu, Dunfeng Xiang, Wenjiao Xiao","doi":"10.1111/ter.12682","DOIUrl":"https://doi.org/10.1111/ter.12682","url":null,"abstract":"Abstract The impact of tectonics, volcanism and climate in controlling temporal and spatial variations in rift‐basin sedimentation is still poorly understood. Here, we tackle this issue by the analysis of mid‐Cretaceous sediments deposited in the Songliao Basin, northeastern China. We present new zircon U–Pb, apatite fission‐track and trace‐element data from the northeastern basin, which are discussed within the framework of the published geochronology dataset. Our results reveal a major provenance change from syn‐rift tectonic extension to post‐rift thermal subsidence at ~103 Ma. During the syn‐rift stage, the detrital inputs were dominantly from transverse rivers sourced from the surrounding mountains including graben shoulders and volcanoes. During the post‐rift stage and coeval thermal subsidence, the basin sedimentation was controlled by coexisting transverse and axial drainage systems sourced from uplifting regions in the south. We conclude that tectonics, not climate, exerted a major control in sediment provenance change in the mid‐Cretaceous Songliao Basin.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135815486","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}
Abstract Ancient orogens within the supercontinent like Columbia can remain stable evolution as long as the cratons. What kind of lithospheric mantle was beneath those orogens and how it evolved into a stable state are still enigmatic. The Trans‐North China orogen (TNCO) is one of the typical collisional orogens within the Columbia supercontinent and was formed at ca. 1.85 Ga. Our work reveals that a cluster of kimberlites intruded the orogenic belt at ca. 1.54 Ga. These rocks were originally generated under a thick lithosphere (>200 km). Their entrained olivine cores show a composition of overlapping olivines from refractory mantle peridotites. The results suggest a thick and refractory lithospheric mantle beneath the TNCO at ca. 1.54 Ga. Such craton‐like property may result from large volume melt extraction from the lithospheric mantle, possibly caused by the ca. 1.78 Ga large igneous event, which eventually induces the long‐term stability of the TNCO during the subsequent supercontinent cycle.
{"title":"A craton‐like subcontinental lithospheric mantle beneath the Trans‐North China Orogen revealed by the ca. 1.54 Ga kimberlites","authors":"Yu‐Sheng Zhu, Jin‐Hui Yang, Qiu‐Li Li, Hao Wang, Ya‐Dong Wu, Fu‐Yuan Wu","doi":"10.1111/ter.12683","DOIUrl":"https://doi.org/10.1111/ter.12683","url":null,"abstract":"Abstract Ancient orogens within the supercontinent like Columbia can remain stable evolution as long as the cratons. What kind of lithospheric mantle was beneath those orogens and how it evolved into a stable state are still enigmatic. The Trans‐North China orogen (TNCO) is one of the typical collisional orogens within the Columbia supercontinent and was formed at ca. 1.85 Ga. Our work reveals that a cluster of kimberlites intruded the orogenic belt at ca. 1.54 Ga. These rocks were originally generated under a thick lithosphere (>200 km). Their entrained olivine cores show a composition of overlapping olivines from refractory mantle peridotites. The results suggest a thick and refractory lithospheric mantle beneath the TNCO at ca. 1.54 Ga. Such craton‐like property may result from large volume melt extraction from the lithospheric mantle, possibly caused by the ca. 1.78 Ga large igneous event, which eventually induces the long‐term stability of the TNCO during the subsequent supercontinent cycle.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136136090","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}
Abstract The North‐South Gravity Lineament (NSGL), characterized by an abrupt variation in both the Bouguer gravity anomaly and topography, acts as a significant geological boundary in eastern China. The formation of such a lateral feature is believed to be associated with lithospheric thinning. The Songliao Basin (SLB) is considered to mark the centre of the lithospheric thinning in Northeast China, whereas its thinning mechanism remains unclear. Here we perform integrated geophysical‐petrological modelling of the crust and upper mantle structure along a passive‐source seismic profile crossing the NSGL, to understand the thinning mechanism beneath the SLB based on the constructed lithospheric extension and delamination models. Our delamination model identifies the compositional variation across the NSGL and the S‐wave velocity signature dominated by high velocity beneath the SLB, which are compatible with previous geochemical and geophysical results. The multidisciplinary analyses suggest that the lithospheric delamination is a plausible mechanism to account for the thinning to the east of the NSGL. The resulting model also shows that the NSGL is a lithospheric‐scale geophysical and geochemical boundary separating two distinct structural domains. In combination with previous evidence, structural discrepancies across the NSGL can be attributed to the lithospheric delamination driven by the subduction of the Palaeo‐Pacific plate.
{"title":"Geophysical‐petrological modelling of the crust and upper mantle structure across the North‐South Gravity Lineament in <scp>NE</scp> China: Insights into the lithospheric thinning mechanism","authors":"Sheng Zhu, Yangfan Deng, Zhou Zhang, Xin Li","doi":"10.1111/ter.12684","DOIUrl":"https://doi.org/10.1111/ter.12684","url":null,"abstract":"Abstract The North‐South Gravity Lineament (NSGL), characterized by an abrupt variation in both the Bouguer gravity anomaly and topography, acts as a significant geological boundary in eastern China. The formation of such a lateral feature is believed to be associated with lithospheric thinning. The Songliao Basin (SLB) is considered to mark the centre of the lithospheric thinning in Northeast China, whereas its thinning mechanism remains unclear. Here we perform integrated geophysical‐petrological modelling of the crust and upper mantle structure along a passive‐source seismic profile crossing the NSGL, to understand the thinning mechanism beneath the SLB based on the constructed lithospheric extension and delamination models. Our delamination model identifies the compositional variation across the NSGL and the S‐wave velocity signature dominated by high velocity beneath the SLB, which are compatible with previous geochemical and geophysical results. The multidisciplinary analyses suggest that the lithospheric delamination is a plausible mechanism to account for the thinning to the east of the NSGL. The resulting model also shows that the NSGL is a lithospheric‐scale geophysical and geochemical boundary separating two distinct structural domains. In combination with previous evidence, structural discrepancies across the NSGL can be attributed to the lithospheric delamination driven by the subduction of the Palaeo‐Pacific plate.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136308849","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}
Junpeng Wang, Yunzhe Jiao, K. Jiang, T. Kusky, Lu Wang, H. Deng
Tectono‐thermal records older than ca. 1.8 Ga in the North China craton have been poorly resolved given that they have been strongly overprinted by younger events, despite being key to understanding the tectonic evolution of the craton. We report results of monazite Th–U–Pb isochron geochronology via electron probe microanalysis on the Zanhuang massif in the North China craton, to determine its detailed Precambrian tectono‐thermal history. Results suggest that the ca. 2.1 Ga tectono‐thermal event can be divided into distinct ca. 2.17 Ga and ca. 2.10 Ga stages, reflecting metamorphism related to retroarc regional extension of the North China craton. Similarly, the previously established ca. 1.8 Ga metamorphic event can be divided into distinct ca. 1.88 Ga and ca. 1.79 Ma stages. Through a detailed summary and comparison, we interpret that the ca. 1.88 Ga monazite age reflects the timing of peak metamorphism, which was followed by ca. 1.79 Ga retrogression.
{"title":"Two Paleoproterozoic tectono‐thermal events in the Central Orogenic belt, North China craton, determined from EPMA Th–U–Pb monazite geochronology of the Zanhuang massif","authors":"Junpeng Wang, Yunzhe Jiao, K. Jiang, T. Kusky, Lu Wang, H. Deng","doi":"10.1111/ter.12680","DOIUrl":"https://doi.org/10.1111/ter.12680","url":null,"abstract":"Tectono‐thermal records older than ca. 1.8 Ga in the North China craton have been poorly resolved given that they have been strongly overprinted by younger events, despite being key to understanding the tectonic evolution of the craton. We report results of monazite Th–U–Pb isochron geochronology via electron probe microanalysis on the Zanhuang massif in the North China craton, to determine its detailed Precambrian tectono‐thermal history. Results suggest that the ca. 2.1 Ga tectono‐thermal event can be divided into distinct ca. 2.17 Ga and ca. 2.10 Ga stages, reflecting metamorphism related to retroarc regional extension of the North China craton. Similarly, the previously established ca. 1.8 Ga metamorphic event can be divided into distinct ca. 1.88 Ga and ca. 1.79 Ma stages. Through a detailed summary and comparison, we interpret that the ca. 1.88 Ga monazite age reflects the timing of peak metamorphism, which was followed by ca. 1.79 Ga retrogression.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"1 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41761215","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}
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