{"title":"南极洲昴宿星团火山场晶体货物的质地和化学性质:冰载荷在调节管道系统方面的潜在影响","authors":"Rocchi Irene, Tomassini Alice, Masotta Matteo, Petrelli Maurizio, Ágreda López Mónica, Rocchi Sergio","doi":"10.1093/petrology/egae027","DOIUrl":null,"url":null,"abstract":"The Pleiades Volcanic Field (PVF) of northern Victoria Land (Antarctica) is made up of a dozen scoria cones whose erupted products present an unusually complete evolutionary trend from alkali-basalt to trachyte. With the aim of reconstructing the evolution of the PVF plumbing system, we have investigated the petrography and chemistry of main mineral phases using SEM-EDS coupled with major (EPMA-WDS) element analyses. We further focussed on clinopyroxene phenocrysts obtaining a more detailed characterisation by means of trace (LA-ICP-MS) element analyses coupled with machine learning thermobarometry. The results indicate that fractional crystallisation and magma mixing are the major processes determining the development of the complete evolution trend. While fractional crystallisation is a persistently active process in all parts of the plumbing system, mixing among differently evolved magma batches pertaining to the same association is responsible for the formation of intermediate compositions in the differentiation lineage at a specific pressure range (0.4-0.5 GPa). These processes are compatible with significant residence time of magmas at depth, resulting in multiple episodes of magma mixing, as testified by resorption and overgrowth textures in phenocryst assemblage occurring under isobaric conditions. The prolonged residence time likely increased the efficiency of the mixing process, leading to the formation of magmas with intermediate composition. In turn, the build-up of volatiles during the magma differentiation at depth could have favoured the eruption of these (variably differentiated) magmas. Considering that the PVF is situated in a glacial region, a process forcing long magma residence time can be envisaged associated with increased ice loading during glacial stages. This study specifically considers the ice fluctuations in the last 100 ka, theorising the possibility of a climate-controlled volcano plumbing system.","PeriodicalId":16751,"journal":{"name":"Journal of Petrology","volume":null,"pages":null},"PeriodicalIF":3.5000,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Textures and chemistry of crystal cargo of The Pleiades Volcanic Field, Antarctica: potential influence of ice load in modulating the plumbing system\",\"authors\":\"Rocchi Irene, Tomassini Alice, Masotta Matteo, Petrelli Maurizio, Ágreda López Mónica, Rocchi Sergio\",\"doi\":\"10.1093/petrology/egae027\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"The Pleiades Volcanic Field (PVF) of northern Victoria Land (Antarctica) is made up of a dozen scoria cones whose erupted products present an unusually complete evolutionary trend from alkali-basalt to trachyte. With the aim of reconstructing the evolution of the PVF plumbing system, we have investigated the petrography and chemistry of main mineral phases using SEM-EDS coupled with major (EPMA-WDS) element analyses. We further focussed on clinopyroxene phenocrysts obtaining a more detailed characterisation by means of trace (LA-ICP-MS) element analyses coupled with machine learning thermobarometry. The results indicate that fractional crystallisation and magma mixing are the major processes determining the development of the complete evolution trend. While fractional crystallisation is a persistently active process in all parts of the plumbing system, mixing among differently evolved magma batches pertaining to the same association is responsible for the formation of intermediate compositions in the differentiation lineage at a specific pressure range (0.4-0.5 GPa). These processes are compatible with significant residence time of magmas at depth, resulting in multiple episodes of magma mixing, as testified by resorption and overgrowth textures in phenocryst assemblage occurring under isobaric conditions. The prolonged residence time likely increased the efficiency of the mixing process, leading to the formation of magmas with intermediate composition. In turn, the build-up of volatiles during the magma differentiation at depth could have favoured the eruption of these (variably differentiated) magmas. Considering that the PVF is situated in a glacial region, a process forcing long magma residence time can be envisaged associated with increased ice loading during glacial stages. 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引用次数: 0
摘要
南极洲维多利亚陆地北部的昴宿星团火山场(PVF)由十几个火山灰锥组成,其喷发产物呈现出从碱性玄武岩到斜长岩的异常完整的演化趋势。为了重建 PVF 管道系统的演化过程,我们利用扫描电镜-电子显微镜和主要(EPMA-WDS)元素分析,对主要矿物相的岩相学和化学性质进行了研究。我们还通过痕量(LA-ICP-MS)元素分析和机器学习热压测量法,对陨石表晶进行了更详细的表征。结果表明,碎裂结晶和岩浆混合是决定完整演化趋势发展的主要过程。在管道系统的所有部分,碎裂结晶都是一个持续活跃的过程,而在特定的压力范围(0.4-0.5 GPa)内,属于同一联合体的不同演化岩浆批次之间的混合则是形成分异系中间成分的原因。这些过程与岩浆在深部的大量停留时间相适应,从而导致岩浆的多次混合,在等压条件下发生的表晶集合体的吸收和过度生长纹理就证明了这一点。停留时间的延长可能会提高混合过程的效率,从而形成具有中间成分的岩浆。反过来,岩浆在深部分化过程中挥发物的积累可能有利于这些(不同分化的)岩浆的喷发。考虑到滨海火山带位于冰川地区,可以设想在冰川期冰负荷增加的情况下,岩浆停留时间较长。本研究特别考虑了过去 100 ka 年的冰层波动,推测了气候控制火山管道系统的可能性。
Textures and chemistry of crystal cargo of The Pleiades Volcanic Field, Antarctica: potential influence of ice load in modulating the plumbing system
The Pleiades Volcanic Field (PVF) of northern Victoria Land (Antarctica) is made up of a dozen scoria cones whose erupted products present an unusually complete evolutionary trend from alkali-basalt to trachyte. With the aim of reconstructing the evolution of the PVF plumbing system, we have investigated the petrography and chemistry of main mineral phases using SEM-EDS coupled with major (EPMA-WDS) element analyses. We further focussed on clinopyroxene phenocrysts obtaining a more detailed characterisation by means of trace (LA-ICP-MS) element analyses coupled with machine learning thermobarometry. The results indicate that fractional crystallisation and magma mixing are the major processes determining the development of the complete evolution trend. While fractional crystallisation is a persistently active process in all parts of the plumbing system, mixing among differently evolved magma batches pertaining to the same association is responsible for the formation of intermediate compositions in the differentiation lineage at a specific pressure range (0.4-0.5 GPa). These processes are compatible with significant residence time of magmas at depth, resulting in multiple episodes of magma mixing, as testified by resorption and overgrowth textures in phenocryst assemblage occurring under isobaric conditions. The prolonged residence time likely increased the efficiency of the mixing process, leading to the formation of magmas with intermediate composition. In turn, the build-up of volatiles during the magma differentiation at depth could have favoured the eruption of these (variably differentiated) magmas. Considering that the PVF is situated in a glacial region, a process forcing long magma residence time can be envisaged associated with increased ice loading during glacial stages. This study specifically considers the ice fluctuations in the last 100 ka, theorising the possibility of a climate-controlled volcano plumbing system.
期刊介绍:
The Journal of Petrology provides an international forum for the publication of high quality research in the broad field of igneous and metamorphic petrology and petrogenesis. Papers published cover a vast range of topics in areas such as major element, trace element and isotope geochemistry and geochronology applied to petrogenesis; experimental petrology; processes of magma generation, differentiation and emplacement; quantitative studies of rock-forming minerals and their paragenesis; regional studies of igneous and meta morphic rocks which contribute to the solution of fundamental petrological problems; theoretical modelling of petrogenetic processes.