{"title":"印度西北部地壳结构和成分的显著变化:岩浆活动的印迹","authors":"B. Gowthami, D.S. Saju, G. Mohan","doi":"10.1016/j.pepi.2024.107198","DOIUrl":null,"url":null,"abstract":"<div><p>Northwestern India was affected by the Neoproterozoic Malani and Erinpura magmatism, Cretaceous rifting, and magmatism associated with the Deccan precursors. Receiver function analysis was done using 1704 RFs from 18 stations to image and decipher the imprints of the magmatic events and comprehend the crustal modifications in terms of variations in structure and composition. The H-κ grid search and neighbourhood inversion techniques are used to retrieve the crustal structure and Vp/Vs ratios (<span><math><mi>κ</mi></math></span>). The study reveals significant variations in the crustal thickness (H = 34 km to 43 km), composition (<span><math><mi>κ</mi><mspace></mspace></math></span>=1.74 to 1.92) and shear wave velocity structure across northwestern India. The terrains encompassing the Erinpura granite and the Malani igneous suite in the vicinity of the Barmer rift are characterized by a thick (H ≥ 41 km) crust with felsic to intermediate composition (<span><math><mi>κ</mi></math></span> ≤ 1.81). The crust beneath the southern part of the Marwar basin is ≈ 38–40 km thick with mafic composition (<span><math><mi>κ</mi><mspace></mspace></math></span>> 1.81). The region around the Barmer rift has a thin crust (H = 34–36 km) with intermediate to mafic composition. The region hosting the Early Cretaceous to Paleogene alkaline complexes exhibits a high Vp/Vs ratio (<span><math><mi>κ</mi><mspace></mspace></math></span>= 1.91) that may be associated with mafic cumulates emplaced by magmatic events that overprint the signatures of the Malani event. The crust is heterogeneous with low/high velocity intracrustal layers that reflect the fractionation of magma at different depths. The mafic residue, together with magmatic intrusions, results in a mafic lowermost crust with high shear velocities of 3.9–4.0 km/s beneath most stations. Overall, northwestern India is characterized by a thick crust with intermediate crustal composition and intracrustal layering resulting from large scale magmatic events linked to the Neoproterozoic reorganization of plates and younger magmatic events.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"352 ","pages":"Article 107198"},"PeriodicalIF":2.4000,"publicationDate":"2024-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Significant variations in the structure and composition of the crust beneath northwestern India: Imprints of magmatism\",\"authors\":\"B. Gowthami, D.S. Saju, G. Mohan\",\"doi\":\"10.1016/j.pepi.2024.107198\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Northwestern India was affected by the Neoproterozoic Malani and Erinpura magmatism, Cretaceous rifting, and magmatism associated with the Deccan precursors. Receiver function analysis was done using 1704 RFs from 18 stations to image and decipher the imprints of the magmatic events and comprehend the crustal modifications in terms of variations in structure and composition. The H-κ grid search and neighbourhood inversion techniques are used to retrieve the crustal structure and Vp/Vs ratios (<span><math><mi>κ</mi></math></span>). The study reveals significant variations in the crustal thickness (H = 34 km to 43 km), composition (<span><math><mi>κ</mi><mspace></mspace></math></span>=1.74 to 1.92) and shear wave velocity structure across northwestern India. The terrains encompassing the Erinpura granite and the Malani igneous suite in the vicinity of the Barmer rift are characterized by a thick (H ≥ 41 km) crust with felsic to intermediate composition (<span><math><mi>κ</mi></math></span> ≤ 1.81). The crust beneath the southern part of the Marwar basin is ≈ 38–40 km thick with mafic composition (<span><math><mi>κ</mi><mspace></mspace></math></span>> 1.81). The region around the Barmer rift has a thin crust (H = 34–36 km) with intermediate to mafic composition. The region hosting the Early Cretaceous to Paleogene alkaline complexes exhibits a high Vp/Vs ratio (<span><math><mi>κ</mi><mspace></mspace></math></span>= 1.91) that may be associated with mafic cumulates emplaced by magmatic events that overprint the signatures of the Malani event. The crust is heterogeneous with low/high velocity intracrustal layers that reflect the fractionation of magma at different depths. The mafic residue, together with magmatic intrusions, results in a mafic lowermost crust with high shear velocities of 3.9–4.0 km/s beneath most stations. Overall, northwestern India is characterized by a thick crust with intermediate crustal composition and intracrustal layering resulting from large scale magmatic events linked to the Neoproterozoic reorganization of plates and younger magmatic events.</p></div>\",\"PeriodicalId\":54614,\"journal\":{\"name\":\"Physics of the Earth and Planetary Interiors\",\"volume\":\"352 \",\"pages\":\"Article 107198\"},\"PeriodicalIF\":2.4000,\"publicationDate\":\"2024-04-21\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Physics of the Earth and Planetary Interiors\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0031920124000566\",\"RegionNum\":3,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"GEOCHEMISTRY & GEOPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Physics of the Earth and Planetary Interiors","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0031920124000566","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
Significant variations in the structure and composition of the crust beneath northwestern India: Imprints of magmatism
Northwestern India was affected by the Neoproterozoic Malani and Erinpura magmatism, Cretaceous rifting, and magmatism associated with the Deccan precursors. Receiver function analysis was done using 1704 RFs from 18 stations to image and decipher the imprints of the magmatic events and comprehend the crustal modifications in terms of variations in structure and composition. The H-κ grid search and neighbourhood inversion techniques are used to retrieve the crustal structure and Vp/Vs ratios (). The study reveals significant variations in the crustal thickness (H = 34 km to 43 km), composition (=1.74 to 1.92) and shear wave velocity structure across northwestern India. The terrains encompassing the Erinpura granite and the Malani igneous suite in the vicinity of the Barmer rift are characterized by a thick (H ≥ 41 km) crust with felsic to intermediate composition ( ≤ 1.81). The crust beneath the southern part of the Marwar basin is ≈ 38–40 km thick with mafic composition (> 1.81). The region around the Barmer rift has a thin crust (H = 34–36 km) with intermediate to mafic composition. The region hosting the Early Cretaceous to Paleogene alkaline complexes exhibits a high Vp/Vs ratio (= 1.91) that may be associated with mafic cumulates emplaced by magmatic events that overprint the signatures of the Malani event. The crust is heterogeneous with low/high velocity intracrustal layers that reflect the fractionation of magma at different depths. The mafic residue, together with magmatic intrusions, results in a mafic lowermost crust with high shear velocities of 3.9–4.0 km/s beneath most stations. Overall, northwestern India is characterized by a thick crust with intermediate crustal composition and intracrustal layering resulting from large scale magmatic events linked to the Neoproterozoic reorganization of plates and younger magmatic events.
期刊介绍:
Launched in 1968 to fill the need for an international journal in the field of planetary physics, geodesy and geophysics, Physics of the Earth and Planetary Interiors has now grown to become important reading matter for all geophysicists. It is the only journal to be entirely devoted to the physical and chemical processes of planetary interiors.
Original research papers, review articles, short communications and book reviews are all published on a regular basis; and from time to time special issues of the journal are devoted to the publication of the proceedings of symposia and congresses which the editors feel will be of particular interest to the reader.