Dominique Cluzel, A. Montanini, A. Secchiari, E. Ferrari, M. Heizler, F. Jourdan, S. Meffre, R. Zhou, C. Teyssier
{"title":"新喀里多尼亚蛇绿混杂岩(西南太平洋)弧前侵入岩的新地球化学和年龄约束(40 Ar/39 Ar 和 U-Pb):热俯冲起始处产生的熔体的多样性","authors":"Dominique Cluzel, A. Montanini, A. Secchiari, E. Ferrari, M. Heizler, F. Jourdan, S. Meffre, R. Zhou, C. Teyssier","doi":"10.1144/jgs2023-145","DOIUrl":null,"url":null,"abstract":"\n New Caledonia Ophiolite is crosscut by coarse to medium grained pyroxenites and hornblende gabbros/diorites dykes intruded between 55.5Ma and 50Ma (U-Pb zircon and\n 40\n Ar/\n 39\n Ar hornblende), while finer-grained dolerites of tholeiitic affinity are younger (50-47 Ma). Production of hornblende-gabbros/diorites was modelled by moderate degree (20-40%) of partial melting of the HT amphibolites of the metamorphic sole. End-member compositions, hornblendites and anorthosites, resulted from solid-state phase segregation of crystal mushes within tectonically active magmatic conduits. Cascade reactions of slab melts with mantle wedge peridotites successively formed clinoenstatite-boninite magmas, which fed gabbronorite cumulate lenses at the mantle-crust transition, in turn clinoenstatite-boninite melts reacted with peridotites to form websterites. The youngest magmas of tholeiitic affinity, appeared about 6 Ma after subduction inception when the cooler subducting slab plunged more steeply. Incipient slab retreat allowed corner flow, triggering low pressure hydrous melting of the uplifted asthenosphere . The early stages of forearc magmatism were closely associated with transcurrent shear zones, which recorded oblique subduction inception. The lower Eocene tectonic and magmatic features of the New Caledonia ophiolite witness the existence of a north- or northeast-dipping hot (forced) subduction zone in the Southwest Pacific, which appears notably distinct from the slightly younger west-dipping Izu-Bonin-Marianna cold (spontaneous) subduction system.\n \n \n Thematic collection:\n This article is part of the Ophiolites, melanges and blueschists collection available at:\n https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists\n \n \n Supplementary material:\n https://doi.org/10.6084/m9.figshare.c.6949265\n","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":null,"pages":null},"PeriodicalIF":2.6000,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"New geochemical and age constraints (\\n 40\\n Ar/\\n 39\\n Ar and U-Pb) on forearc intrusive rocks from New Caledonia Ophiolite (SW Pacific): diversity of melts generated at hot subduction inception\",\"authors\":\"Dominique Cluzel, A. Montanini, A. Secchiari, E. Ferrari, M. Heizler, F. Jourdan, S. Meffre, R. Zhou, C. Teyssier\",\"doi\":\"10.1144/jgs2023-145\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"\\n New Caledonia Ophiolite is crosscut by coarse to medium grained pyroxenites and hornblende gabbros/diorites dykes intruded between 55.5Ma and 50Ma (U-Pb zircon and\\n 40\\n Ar/\\n 39\\n Ar hornblende), while finer-grained dolerites of tholeiitic affinity are younger (50-47 Ma). Production of hornblende-gabbros/diorites was modelled by moderate degree (20-40%) of partial melting of the HT amphibolites of the metamorphic sole. End-member compositions, hornblendites and anorthosites, resulted from solid-state phase segregation of crystal mushes within tectonically active magmatic conduits. Cascade reactions of slab melts with mantle wedge peridotites successively formed clinoenstatite-boninite magmas, which fed gabbronorite cumulate lenses at the mantle-crust transition, in turn clinoenstatite-boninite melts reacted with peridotites to form websterites. The youngest magmas of tholeiitic affinity, appeared about 6 Ma after subduction inception when the cooler subducting slab plunged more steeply. Incipient slab retreat allowed corner flow, triggering low pressure hydrous melting of the uplifted asthenosphere . The early stages of forearc magmatism were closely associated with transcurrent shear zones, which recorded oblique subduction inception. The lower Eocene tectonic and magmatic features of the New Caledonia ophiolite witness the existence of a north- or northeast-dipping hot (forced) subduction zone in the Southwest Pacific, which appears notably distinct from the slightly younger west-dipping Izu-Bonin-Marianna cold (spontaneous) subduction system.\\n \\n \\n Thematic collection:\\n This article is part of the Ophiolites, melanges and blueschists collection available at:\\n https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists\\n \\n \\n Supplementary material:\\n https://doi.org/10.6084/m9.figshare.c.6949265\\n\",\"PeriodicalId\":17320,\"journal\":{\"name\":\"Journal of the Geological Society\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.6000,\"publicationDate\":\"2023-12-12\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of the Geological Society\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://doi.org/10.1144/jgs2023-145\",\"RegionNum\":3,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"GEOSCIENCES, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of the Geological Society","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1144/jgs2023-145","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
New geochemical and age constraints (
40
Ar/
39
Ar and U-Pb) on forearc intrusive rocks from New Caledonia Ophiolite (SW Pacific): diversity of melts generated at hot subduction inception
New Caledonia Ophiolite is crosscut by coarse to medium grained pyroxenites and hornblende gabbros/diorites dykes intruded between 55.5Ma and 50Ma (U-Pb zircon and
40
Ar/
39
Ar hornblende), while finer-grained dolerites of tholeiitic affinity are younger (50-47 Ma). Production of hornblende-gabbros/diorites was modelled by moderate degree (20-40%) of partial melting of the HT amphibolites of the metamorphic sole. End-member compositions, hornblendites and anorthosites, resulted from solid-state phase segregation of crystal mushes within tectonically active magmatic conduits. Cascade reactions of slab melts with mantle wedge peridotites successively formed clinoenstatite-boninite magmas, which fed gabbronorite cumulate lenses at the mantle-crust transition, in turn clinoenstatite-boninite melts reacted with peridotites to form websterites. The youngest magmas of tholeiitic affinity, appeared about 6 Ma after subduction inception when the cooler subducting slab plunged more steeply. Incipient slab retreat allowed corner flow, triggering low pressure hydrous melting of the uplifted asthenosphere . The early stages of forearc magmatism were closely associated with transcurrent shear zones, which recorded oblique subduction inception. The lower Eocene tectonic and magmatic features of the New Caledonia ophiolite witness the existence of a north- or northeast-dipping hot (forced) subduction zone in the Southwest Pacific, which appears notably distinct from the slightly younger west-dipping Izu-Bonin-Marianna cold (spontaneous) subduction system.
Thematic collection:
This article is part of the Ophiolites, melanges and blueschists collection available at:
https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists
Supplementary material:
https://doi.org/10.6084/m9.figshare.c.6949265
期刊介绍:
Journal of the Geological Society (JGS) is owned and published by the Geological Society of London.
JGS publishes topical, high-quality recent research across the full range of Earth Sciences. Papers are interdisciplinary in nature and emphasize the development of an understanding of fundamental geological processes. Broad interest articles that refer to regional studies, but which extend beyond their geographical context are also welcomed.
Each year JGS presents the ‘JGS Early Career Award'' for papers published in the journal, which rewards the writing of well-written, exciting papers from early career geologists.
The journal publishes research and invited review articles, discussion papers and thematic sets.