{"title":"缓慢扩张的大洋堆积过程中显著的熔融-泥沙反应的岩石学证据","authors":"Marine Boulanger, Marguerite Godard, Benoit Ildefonse, Malissa Bakouche","doi":"10.1029/2023GC011409","DOIUrl":null,"url":null,"abstract":"<p>The structure of the lithosphere and the associated magmatic systems found in different locations along slow-spreading ridges can vary dramatically, from melt-starved to magmatically robust segments. A growing number of studies suggest that the evolution of the magmatic crust being governed solely by fractional crystallization is too simplistic. Reactions between migrating melts and their surroundings play a key role during accretion, yet the full extent of their impact is still to be resolved. We present here the results of a petrological, microstructural, and in situ geochemical study of two drilled sequences from the Kane Megamullion and Atlantis Massif oceanic core complexes. We show that melt-mush reactions generate locally strong textural and/or geochemical heterogeneity at the cm-scale, but their impact can also be identified at the 100 m-scale. We found evidence for assimilation at various degrees of primitive lithologies of potential mantle origin within the gabbroic sequence at both locations, in addition to typical melt-mush reactions previously described in other slow-spread magmatic systems. Observations and numerical modeling confirm the similarity of the reactions impacting both sequences. However, the regime of the reactions (ranges of assimilation to crystallization ratios) seems to vary between Kane Megamullion and Atlantis Massif, variations which likely result from differences in melt fractions present during melt-mush reactions. We infer relying on our observations and previous studies that the regime of the reactions is most likely controlled by the melt flux during the formation of the two sections.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":null,"pages":null},"PeriodicalIF":2.9000,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023GC011409","citationCount":"0","resultStr":"{\"title\":\"Petrological Evidence for Prominent Melt-Mush Reactions During Slow-Spreading Oceanic Accretion\",\"authors\":\"Marine Boulanger, Marguerite Godard, Benoit Ildefonse, Malissa Bakouche\",\"doi\":\"10.1029/2023GC011409\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>The structure of the lithosphere and the associated magmatic systems found in different locations along slow-spreading ridges can vary dramatically, from melt-starved to magmatically robust segments. A growing number of studies suggest that the evolution of the magmatic crust being governed solely by fractional crystallization is too simplistic. Reactions between migrating melts and their surroundings play a key role during accretion, yet the full extent of their impact is still to be resolved. We present here the results of a petrological, microstructural, and in situ geochemical study of two drilled sequences from the Kane Megamullion and Atlantis Massif oceanic core complexes. We show that melt-mush reactions generate locally strong textural and/or geochemical heterogeneity at the cm-scale, but their impact can also be identified at the 100 m-scale. We found evidence for assimilation at various degrees of primitive lithologies of potential mantle origin within the gabbroic sequence at both locations, in addition to typical melt-mush reactions previously described in other slow-spread magmatic systems. Observations and numerical modeling confirm the similarity of the reactions impacting both sequences. However, the regime of the reactions (ranges of assimilation to crystallization ratios) seems to vary between Kane Megamullion and Atlantis Massif, variations which likely result from differences in melt fractions present during melt-mush reactions. We infer relying on our observations and previous studies that the regime of the reactions is most likely controlled by the melt flux during the formation of the two sections.</p>\",\"PeriodicalId\":50422,\"journal\":{\"name\":\"Geochemistry Geophysics Geosystems\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.9000,\"publicationDate\":\"2024-08-21\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023GC011409\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Geochemistry Geophysics Geosystems\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1029/2023GC011409\",\"RegionNum\":2,\"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":"Geochemistry Geophysics Geosystems","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1029/2023GC011409","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
Petrological Evidence for Prominent Melt-Mush Reactions During Slow-Spreading Oceanic Accretion
The structure of the lithosphere and the associated magmatic systems found in different locations along slow-spreading ridges can vary dramatically, from melt-starved to magmatically robust segments. A growing number of studies suggest that the evolution of the magmatic crust being governed solely by fractional crystallization is too simplistic. Reactions between migrating melts and their surroundings play a key role during accretion, yet the full extent of their impact is still to be resolved. We present here the results of a petrological, microstructural, and in situ geochemical study of two drilled sequences from the Kane Megamullion and Atlantis Massif oceanic core complexes. We show that melt-mush reactions generate locally strong textural and/or geochemical heterogeneity at the cm-scale, but their impact can also be identified at the 100 m-scale. We found evidence for assimilation at various degrees of primitive lithologies of potential mantle origin within the gabbroic sequence at both locations, in addition to typical melt-mush reactions previously described in other slow-spread magmatic systems. Observations and numerical modeling confirm the similarity of the reactions impacting both sequences. However, the regime of the reactions (ranges of assimilation to crystallization ratios) seems to vary between Kane Megamullion and Atlantis Massif, variations which likely result from differences in melt fractions present during melt-mush reactions. We infer relying on our observations and previous studies that the regime of the reactions is most likely controlled by the melt flux during the formation of the two sections.
期刊介绍:
Geochemistry, Geophysics, Geosystems (G3) publishes research papers on Earth and planetary processes with a focus on understanding the Earth as a system. Observational, experimental, and theoretical investigations of the solid Earth, hydrosphere, atmosphere, biosphere, and solar system at all spatial and temporal scales are welcome. Articles should be of broad interest, and interdisciplinary approaches are encouraged.
Areas of interest for this peer-reviewed journal include, but are not limited to:
The physics and chemistry of the Earth, including its structure, composition, physical properties, dynamics, and evolution
Principles and applications of geochemical proxies to studies of Earth history
The physical properties, composition, and temporal evolution of the Earth''s major reservoirs and the coupling between them
The dynamics of geochemical and biogeochemical cycles at all spatial and temporal scales
Physical and cosmochemical constraints on the composition, origin, and evolution of the Earth and other terrestrial planets
The chemistry and physics of solar system materials that are relevant to the formation, evolution, and current state of the Earth and the planets
Advances in modeling, observation, and experimentation that are of widespread interest in the geosciences.