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Mesozoic lithospheric mantle evolution in South China: Evidence from Ar-Ar dating, geochemistry and Sr-Nd-Pb isotopes of lamprophyres 华南中生代岩石圈地幔演化:从Ar-Ar测年、地球化学和灯石的Sr-Nd-Pb同位素得出的证据
IF 2.9 2区 地球科学
Lithos Pub Date : 2024-11-06 DOI: 10.1016/j.lithos.2024.107851
Lei Wang , Hua Huang , Xinbiao Jin , Xiujuan Bai , Xinyu Wang , Xiangke Wu
{"title":"Mesozoic lithospheric mantle evolution in South China: Evidence from Ar-Ar dating, geochemistry and Sr-Nd-Pb isotopes of lamprophyres","authors":"Lei Wang ,&nbsp;Hua Huang ,&nbsp;Xinbiao Jin ,&nbsp;Xiujuan Bai ,&nbsp;Xinyu Wang ,&nbsp;Xiangke Wu","doi":"10.1016/j.lithos.2024.107851","DOIUrl":"10.1016/j.lithos.2024.107851","url":null,"abstract":"<div><div>Understanding the Mesozoic lithospheric mantle beneath South China is challenging, primarily because mantle-derived magmatic rocks are rare, whereas granitic magmatism is far more abundant. In this study, we present new <sup>40</sup>Ar/<sup>39</sup>Ar geochronology, major and trace elemental composition, and Sr-Nd-Pb isotopic data for lamprophyres from northern and central Guangxi Province, South China. Our results reveal two intrusion phases: an earlier phase at 207.7 ± 1.2 Ma, and a later phase between 95.6 ± 0.6 Ma and 102.3 ± 0.7 Ma. The earlier phase, represented by the Danyang lamprophyres, is marked by low Cr (330–355 ppm) and Ni (241–258 ppm) contents and strongly fractionated REE patterns with (La/Yb)n ratios of 57.5 to 62.8. The later phase, represented by the Leidong, Nongchang, and Longchang lamprophyres, shows higher Cr (490–781 ppm) and Ni (237–377 ppm) contents, with less fractionated REE patterns and (La/Yb)n ratios of 20.2 to 27.8. Despite their temporal differences, the lamprophyres share similar isotopic characteristics, including high initial <sup>87</sup>Sr/<sup>86</sup>Sr (0.707940–0.721310), negative ε<sub>Nd</sub>(t) (−9.19 to −5.31), and radiogenic Pb isotopic compositions (<sup>206</sup>Pb/<sup>204</sup>Pb: 18.200–18.331, <sup>207</sup>Pb/<sup>204</sup>Pb: 15.62–15.72, <sup>208</sup>Pb/<sup>204</sup>Pb: 38.53–38.84). These features suggest derivation from low-degree partial melting of a phlogopite-bearing, refractory peridotite lithospheric mantle, modified by olivine and clinopyroxene fractionation. This refractory mantle was metasomatically enriched by Proterozoic subduction processes beneath the Yangtze Craton. By synthesizing published Sr-Nd-Pb isotopic data, we propose that the lithospheric mantle beneath South China shifted from enriched to depleted mantle between ∼220 Ma and ∼ 100 Ma, possibly due to extension associated with the subduction and rollback of the Paleo-Pacific Plate.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107851"},"PeriodicalIF":2.9,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Restite entrainment in S-type granites: A systematic review S 型花岗岩中的息石夹带:系统回顾
IF 2.9 2区 地球科学
Lithos Pub Date : 2024-11-05 DOI: 10.1016/j.lithos.2024.107850
M. García-Arias
{"title":"Restite entrainment in S-type granites: A systematic review","authors":"M. García-Arias","doi":"10.1016/j.lithos.2024.107850","DOIUrl":"10.1016/j.lithos.2024.107850","url":null,"abstract":"<div><div>S-type granites show linear correlations for major elements and some trace elements in bivariate diagrams against maficity (FeO<sub>t</sub> + MgO), with negative trends for major incompatible elements and positive trends for major compatible elements, extending beyond the usual composition of experimental and anatectic melts. Although several petrogenetic processes have been suggested, restite entrainment has been prominently proposed to explain that compositional feature. Restite entrainment implies that melt leaves the partially melted source rocks containing variable amounts of the solid phases present in the melting volume, which are generally Ca-Fe-Mg-Ti-richer and Si-Na-K-poorer than the melt. The entrainment of these phases will consequently produce the described compositional trends. In this manuscript I provide a review of this process based on my personal experience with thermodynamic modelling of the partial melting of metasedimentary sources and on conclusions published by other authors. In particular, I review what constitutes restite, the factors that control the entrainment of minerals, the proposed types of restite entrainment, the evidence in favor of (or against) this process, and other related aspects.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107850"},"PeriodicalIF":2.9,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Givetian-Frasnian rift-related volcanism of the Shipunikha Depression, NW Rudny Altai, Central Asia: Tectono-magmatic significance and new constraints on whole-rock geochemistry, Nd-isotopic data and UPb ages 中亚鲁德尼阿尔泰西北部希普尼克哈洼地与纪元-新生代断裂有关的火山活动:构造-岩浆学意义以及对全岩石地球化学、钕同位素数据和 UPb 年龄的新约束
IF 2.9 2区 地球科学
Lithos Pub Date : 2024-11-04 DOI: 10.1016/j.lithos.2024.107849
M.L. Kuibida , N.N. Kruk , I.V. Vikentiev , O.V. Murzin , N.M. Murzina , V.A. Yakovlev , Ya Yu Shelepov , A.V. Chugaev , M.A. Mizernaya , R.A. Shelepaev , P.D. Kotler , E.I. Mikheev , I.V. Nikolaeva , S.V. Palesskiy , D.V. Semenova , N.G. Soloshenko , A.P. Pyatkova , G.F. Karmanov
{"title":"Givetian-Frasnian rift-related volcanism of the Shipunikha Depression, NW Rudny Altai, Central Asia: Tectono-magmatic significance and new constraints on whole-rock geochemistry, Nd-isotopic data and UPb ages","authors":"M.L. Kuibida ,&nbsp;N.N. Kruk ,&nbsp;I.V. Vikentiev ,&nbsp;O.V. Murzin ,&nbsp;N.M. Murzina ,&nbsp;V.A. Yakovlev ,&nbsp;Ya Yu Shelepov ,&nbsp;A.V. Chugaev ,&nbsp;M.A. Mizernaya ,&nbsp;R.A. Shelepaev ,&nbsp;P.D. Kotler ,&nbsp;E.I. Mikheev ,&nbsp;I.V. Nikolaeva ,&nbsp;S.V. Palesskiy ,&nbsp;D.V. Semenova ,&nbsp;N.G. Soloshenko ,&nbsp;A.P. Pyatkova ,&nbsp;G.F. Karmanov","doi":"10.1016/j.lithos.2024.107849","DOIUrl":"10.1016/j.lithos.2024.107849","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The paper presents new original data on the Devonian rift-related volcanism from the Rudny Altai, a marginal terrane of the Siberian continent (Altai-Sayan Fold Belt, western Central Asian Orogenic Belt). The extensional regime in relation to tectono-magmatic reactivation of the continental margin was accompanied by an intense flare up of bimodal-type shallow-marine volcanism and injection of subvolcanic intrusions. On the first stage basic magmatism evolved from (i) injection of “More LREE- and HFSE-enriched” dolerite (&lt;em&gt;ε&lt;/em&gt;&lt;sub&gt;Nd&lt;/sub&gt;(t) = +5.1) to (ii) eruption of their effusive analogues (&lt;em&gt;ε&lt;/em&gt;&lt;sub&gt;Nd&lt;/sub&gt;(t) = +1.4), and following “Less LREE- and HFSE-enriched” basalt (&lt;em&gt;ε&lt;/em&gt;&lt;sub&gt;Nd&lt;/sub&gt;(t) = +6.1). This stage reflects initial opening of the rift. On the second stage, volcanism evolved from (iii) “LREE- and HFSE-depleted” (&lt;em&gt;ε&lt;/em&gt;&lt;sub&gt;Nd&lt;/sub&gt;(t) = +5.4) to (iv) “LREE-enriched and HFSE-depleted” (&lt;em&gt;ε&lt;/em&gt;&lt;sub&gt;Nd&lt;/sub&gt;(t) = +4.1 to +4.7) types. This stage correspond to the prolonged opening of the pull-apart basin, as there is no geological evidence for island-arc uplift during this period. Variations in indicator HFSE ratios (Th/Yb, Nb/Yb and Zr/Y), enrichment of Nb relative to La and Th in combination with moderate Nd isotopic values resemble those for basalts from the behind-arc region with close spatial-temporal relation to rifting. The trace element variation indicates a change in the partial melting degree of the mantle source, from lower to higher, consistent with progressive rifting. The petrogenesis of magmas has been interpreted as shallow melting of a lithospheric mantle, metosomatised by a previous subduction event, and inherited geochemical signatures of relict mantle. The voluminous felsic magmatism was formed by crustal melting during lithospheric extension when basic magmas reached high crustal levels. The dacites yield zircon U&lt;img&gt;Pb ages of ca. 375 Ma, reflecting the peak of volcanic activity. The tectonic record bear evidence of strike-slip deformation, which could been induced by translation of arc and back-arc lithospheric plates.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Summary&lt;/h3&gt;&lt;div&gt;The Devonian evolution of the Altai Convergent Margin (NW Rudny Altai) of the Siberian continent was accompanied by the generation of basalt-dacite volcanism (∼380-375 Ma). Based on the sequence of volcanic phases and their geochemical variations in the time range, two stages corresponding to the initial and long-term opening of the pull-apart basin are distinguished. The petrogenesis of the magmas is interpreted as shallow melting of lithospheric mantle metasomatised by a previous subduction event and inheriting geochemical signatures of the relict mantle. The initial and subsequent magmatic phases can be reproduced by varying the degree of partial melting of the magma source from lower to higher, consistent with the evolution of the pull-apart basin. Rift-related magmatism is caused by arc and back-arc plate translation, wi","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107849"},"PeriodicalIF":2.9,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
First-principles calculations of equilibrium inter-mineral nickel isotope fractionation in the mantle 地幔中矿物质间镍同位素平衡分馏的第一原理计算
IF 2.9 2区 地球科学
Lithos Pub Date : 2024-11-02 DOI: 10.1016/j.lithos.2024.107848
Zhuang Ma , Wenzhong Wang , Shui-Jiong Wang
{"title":"First-principles calculations of equilibrium inter-mineral nickel isotope fractionation in the mantle","authors":"Zhuang Ma ,&nbsp;Wenzhong Wang ,&nbsp;Shui-Jiong Wang","doi":"10.1016/j.lithos.2024.107848","DOIUrl":"10.1016/j.lithos.2024.107848","url":null,"abstract":"<div><div>The nickel (Ni) isotopic systematics has been increasingly utilized to understand the processes governing planetary differentiation. However, there is a lack of fundamental knowledge regarding equilibrium Ni isotope fractionation among mantle minerals, which hampered further applications of Ni isotopes in this domain. In this study, we conducted first-principles calculations to determine the reduced partition function ratios of <sup>60</sup>Ni/<sup>58</sup>Ni (10<sup>3</sup>lnβ<sub>60</sub><sub>–</sub><sub>58</sub>) in major Ni-doped mantle minerals, including olivine, orthopyroxene, clinopyroxene, pyrope and spinel. Our calculations reveal that the 10<sup>3</sup>lnβ<sub>60</sub><sub>–</sub><sub>58</sub> is insensitive to the Ni concentration within the mineral Ni concentration ranges investigated here, and the 10<sup>3</sup>lnβ<sub>60</sub><sub>–</sub><sub>58</sub> increases in the order of pyrope &lt; clinopyroxene &lt; orthopyroxene &lt; olivine &lt; spinel. Moreover, the 10<sup>3</sup>lnβ<sub>60</sub><sub>–</sub><sub>58</sub> demonstrates a predominantly linear relationship with the average force constant (&lt; F &gt;) of Ni that is mainly influenced by the average Ni<img>O bond length. By comparing the measured inter-mineral Ni isotopic differences in mantle rocks with our predicted results, we find that olivine, spinel and orthopyroxene in most peridotitic samples have attained Ni isotopic equilibrium. Conversely, clinopyroxene appears to fall out of equilibrium with other mineral phases, likely attributed to its metasomatic origin. Furthermore, in conjunction with the melt-olivine Ni isotope fractionation factor obtained from theoretical calculation and laboratory experiment, we demonstrate that mantle silicate melting produces melts with a heavier Ni isotopic signature compared to the source. Consequently, the systematically lighter Ni isotopic compositions observed in global basalts cannot be purely attributed to silicate melting-induced Ni isotope fractionation. An additional process, perhaps sulfide dissolution, must be invoked.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107848"},"PeriodicalIF":2.9,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The origin of ∼ 2.5 Ga arc-related magmatic charnockites of Karimnagar, SE India, and implications for tectonic assembly in the Dharwar craton 印度东南部卡里姆纳加尔∼2.5 Ga弧相关岩浆焦绿泥石的起源及其对达瓦尔克拉通构造组装的影响
IF 2.9 2区 地球科学
Lithos Pub Date : 2024-10-30 DOI: 10.1016/j.lithos.2024.107845
Kausik Satpathi , Pritam Nasipuri , Keewook Yi , Youn-Joong Jeong , Alip Roy , Abhijit Bhattacharya
{"title":"The origin of ∼ 2.5 Ga arc-related magmatic charnockites of Karimnagar, SE India, and implications for tectonic assembly in the Dharwar craton","authors":"Kausik Satpathi ,&nbsp;Pritam Nasipuri ,&nbsp;Keewook Yi ,&nbsp;Youn-Joong Jeong ,&nbsp;Alip Roy ,&nbsp;Abhijit Bhattacharya","doi":"10.1016/j.lithos.2024.107845","DOIUrl":"10.1016/j.lithos.2024.107845","url":null,"abstract":"<div><div>In the Indian peninsula, the Singhbhum, Bastar, and Dharwar cratons in the South India Block (SIB) constitute a contiguous mass of &gt;2.5 Ga crystalline rocks. Did the cratons develop as a coherently evolved mass since their origin, or do these cratons constitute an assembly of disparately evolved cratons? Variably-deformed charnockites in the Karimnagar granulite belt and associated blastoporphyritic granitoids at the NE fringe of the Eastern Dharwar Craton (EDC) contain enclaves of mafic granulites, high-Al metapelites and anatectic quartzofeldspathic gneisses. The charnockites are demonstrably intrusive into the enclave suite. The enclave suite exhibits steeply-plunging reclined folds; the axial planes of the folds coincide with the N-striking tectonic fabrics in the Karimnagar charnockite/granitoids. The foliated charnockites display magmatic flow texture defined by trains of euhedral alkali feldspar, contain euhedral-subhedral pyroxene phenocrysts, and the quartz grains exhibit abundant chessboard microstructure. The weakly-strained euhedral laths of feldspars and pyroxenes phenocrysts share high-energy boundaries between themselves, and with quartz. Emplacement temperatures of the magmatic charnockites at ∼900 °C are obtained from Al-in-Opx thermometry. Whole rock chemistry is consistent with an arc-related origin for most charnockites. In zircons within charnockites, variably zoned cores yield ages of 2680 ± 15 Ma and 2504 ± 12 Ma in the U<img>Pb Concordia plot. Recrystallized domains in zircon grains yielded upper intercept ages constrained between 2510 ± 4 Ma and 2509 ± 3 Ma, identical with the U-Th-Pb chemical ages (2502–2508 Ma) retrieved from monazites. The zircon εHf(t) values (− 4.85 to 1.31) suggest the ∼2.5 Ga magmatic charnockites were derived from &lt;3.0 Ga crustal sources. The late Neoarchean magmatic charnockites in the EDC margin were emplaced in a 2.7–2.5 Ga convergent tectonic setting, and the high-<em>T</em> magmatic charnockites formed due to delamination of a subducting (<em>E</em>-W shortening) oceanic crust. The subduction possibly relates to the late Neoarchean growth of the Dharwar craton involving the assembly of disparately-evolved crustal blocks, now parts of the Dharwar craton. The findings suggest that the emplacement of Karimnagar magmatic charnockites in a contractional setting is unrelated to an accretion between the Eastern Dharwar and the Bastar cratons, as suggested by earlier workers.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107845"},"PeriodicalIF":2.9,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142706346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Silurian-devonian adakites and granitic pegmatitic dikes in North Qinling, China: Multi-stage magmatism and implications for the tectonic evolution 中国秦岭北麓志留纪-元古代的斑岩和花岗伟晶岩长脉:多期岩浆活动及其对构造演化的影响
IF 2.9 2区 地球科学
Lithos Pub Date : 2024-10-25 DOI: 10.1016/j.lithos.2024.107838
Guochao Chen , Xiaofei Zhang , Xianzhi Pei , Ruibao Li , Zuochen Li , Junqi Wei , Rongzhen Zhang
{"title":"Silurian-devonian adakites and granitic pegmatitic dikes in North Qinling, China: Multi-stage magmatism and implications for the tectonic evolution","authors":"Guochao Chen ,&nbsp;Xiaofei Zhang ,&nbsp;Xianzhi Pei ,&nbsp;Ruibao Li ,&nbsp;Zuochen Li ,&nbsp;Junqi Wei ,&nbsp;Rongzhen Zhang","doi":"10.1016/j.lithos.2024.107838","DOIUrl":"10.1016/j.lithos.2024.107838","url":null,"abstract":"<div><div>The petrogenesis and tectonic setting of early Paleozoic adakites and granitic pegmatites in the North Qinling orogenic belt are highly debated issues. Zircon U<img>Pb dating revealed that the Huichizi pluton is composed of the Early Silurian granodiorites, Late Silurian granodiorites, and Early Devonian granitic pegmatite dikes. The average ε<sub>Hf</sub>(<em>t</em>) value of pegmatite dikes was −2.8, which is lower than those of the Early Silurian (4.8) and Late Silurian granodiorites (5.1). It is worth noting that the Early Silurian and Late Silurian granodiorites exhibited adakitic characteristics and were formed through the partial melting of a thickened juvenile mafic lower crust. In addition, the Early Devonian pegmatite dikes displayed a substantial fractional crystallization. They were derived from the partial melting of mixed sources, including the crustal and mantle materials. The early Paleozoic adakitic rocks in the North Qinling orogenic belt can be categorized into four groups according to their c geochemical characteristics. The adakitic rocks of the first group (496–458 Ma) were rich in Na and exhibited extremely high ε<sub>Hf</sub>(<em>t</em>) values. They were formed by the partial melting of the Erlangping back-arc oceanic crust. The adakitic rocks of the second group (454–420 Ma) exhibited enriched Na or K contents and varying ε<sub>Hf</sub>(<em>t</em>) values. They were derived from the partial melting of a thickened lower crust with various mantle components, underplated by mafic magma formed during the subduction of the Shangdan Ocean. The adakites of the third (420–410 Ma) and fourth (410–400 Ma) groups were formed by the partial melting of a thickened lower crust under collisional and post-collisional settings, respectively.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107838"},"PeriodicalIF":2.9,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Sulfur and metal mobilization during the life cycle of an oceanic core complex: Implications for seafloor massive sulfide deposits formation at slow and ultra-slow spreading ridges 大洋核心复合体生命周期中的硫和金属动员:对慢速和超慢速扩张海脊海底块状硫化物矿床形成的影响
IF 2.9 2区 地球科学
Lithos Pub Date : 2024-10-24 DOI: 10.1016/j.lithos.2024.107843
C.G.C. Patten , M. Junge , R. Coltat , A.P. Jesus , A. Beranoaguire , P. Tropper , J. Alt
{"title":"Sulfur and metal mobilization during the life cycle of an oceanic core complex: Implications for seafloor massive sulfide deposits formation at slow and ultra-slow spreading ridges","authors":"C.G.C. Patten ,&nbsp;M. Junge ,&nbsp;R. Coltat ,&nbsp;A.P. Jesus ,&nbsp;A. Beranoaguire ,&nbsp;P. Tropper ,&nbsp;J. Alt","doi":"10.1016/j.lithos.2024.107843","DOIUrl":"10.1016/j.lithos.2024.107843","url":null,"abstract":"<div><div>Seafloor massive sulfide (SMS) deposits at slow and ultra-slow spreading ridges are often spatially related to, or hosted in oceanic core complexes (OCCs). The specific oceanic crust architecture, magmatism, hydrothermal fluid circulation and lithologies at OCCs, however, imply different S and metal (e.g. Cu, Zn, Co, Ni) fluxes relative to well-structured oceanic crust at-fast spreading ridges and which are not yet fully constrained. The study of S and metal distribution in the ODP Hole 735B deep drill core from the Atlantis bank allows to understand these fluxes along detachment faults and to better constrain the source zone of S and metals for OCC-related SMS deposits. Significant depletion of S, Cu, Zn and Ni are observed within the upper 250 m of the drill core where intense deformation and hydrothermal fluid circulation occurred. During the complex tectono-magmatic-hydrothermal evolution of the Atlantis Bank, four important stages are recognized for S and metal mobilization: 1) magmatic stratification leading to a higher proportion of sulfide-rich and S, Cu, Zn and Co fertile oxide gabbros in the root zone of the Atlantis Bank detachment, 2) high temperature ductile deformation leading to magmatic sulfide reworking and onset of sulfide leaching with limited metal mobilization, 3) extensive sulfide leaching and metal mobilization during amphibolite to greenschist facies metasomatism and, 4) late stage secondary sulfide precipitation and S enrichment during low temperature fluid circulation. Mass balance calculations from the source zones of the Atlantis Bank detachment highlights that metal mobilization during hydrothermal alteration of gabbroic rocks along detachment faults can fully account for the formation of OCC-related SMS deposits at slow and ultraslow spreading ridges. The Atlantis Bank detachment system, however, is gabbroic-dominated and represent the magmatic end-member of OCCs and further work is necessary for understanding metal fluxes in ultramafic-dominated detachment systems.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107843"},"PeriodicalIF":2.9,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Magmatic stability of eudialyte-group minerals (EGM) and element distribution between EGM and peralkaline silica-undersaturated melts 岩浆岩基团矿物(EGM)的岩浆稳定性以及 EGM 和围岩硅不饱和熔体之间的元素分布
IF 2.9 2区 地球科学
Lithos Pub Date : 2024-10-24 DOI: 10.1016/j.lithos.2024.107839
Anna Nikolenko , Christian Schmidt , Melanie J. Sieber , Valby van Schijndel , Ilya V. Veksler
{"title":"Magmatic stability of eudialyte-group minerals (EGM) and element distribution between EGM and peralkaline silica-undersaturated melts","authors":"Anna Nikolenko ,&nbsp;Christian Schmidt ,&nbsp;Melanie J. Sieber ,&nbsp;Valby van Schijndel ,&nbsp;Ilya V. Veksler","doi":"10.1016/j.lithos.2024.107839","DOIUrl":"10.1016/j.lithos.2024.107839","url":null,"abstract":"<div><div>Eudialyte-group minerals (EGM) are unique tracers of peralkaline silica-undersaturated melts. They receive global interest as potential resources for high-field-strength elements (HFSE, e.g., Zr, Nb, Ta) and rare-earth elements (REE), which are critical materials for modern technologies. The main condition for magmatic crystallization of EGM in general is that the concentration of Zr in the parental melt should reach saturation. The solubility of EGM in peralkaline melts from the system Na<sub>2</sub>O–CaO–Al<sub>2</sub>O<sub>3</sub>–SiO<sub>2</sub> ± H<sub>2</sub>O at temperatures between 750 and 1000 °C and pressures of 100 and 200 MPa was investigated. Newly formed crystalline phases in the run products are EGM grains, parakeldyshite and albite. EGM are stable between 750 and 900 °C, and melt incongruently to parakeldyshite between 900 and 1000 °C. EGM crystallization from peralkaline silica-undersaturated melts at nominally dry conditions and 750–850 °C requires a minimum of 0.2–0.22 wt% ZrO<sub>2</sub> in the melt. In experiments with the addition of H<sub>2</sub>O, saturation is attained at much higher ZrO<sub>2</sub> concentrations (1.1–2.85 wt%) in the same temperature interval. REE and HFSE are strongly compatible with eudialyte-group minerals as the EGM-melt distribution coefficients (<em>D</em>) vary from 2 to 90 with falling temperature. The lowest <em>D</em> values are observed in experiments with the highest Zr solubility, i.e., at high temperature and in hydrated compositions. Light REE and especially La tend to have lower <em>D</em> values than the heavy REE.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107839"},"PeriodicalIF":2.9,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Indosinian magmatism in NE Vietnam: Petrogenesis and geodynamic implications of Triassic mafic suites from the Song Hien region 越南东北部的印支期岩浆活动:松贤地区三叠纪岩浆岩套的成岩作用和地球动力学意义
IF 2.9 2区 地球科学
Lithos Pub Date : 2024-10-24 DOI: 10.1016/j.lithos.2024.107842
Thi Huong Ngo , Tatyana V. Svetlitskaya , Tuan Anh Tran , Andrey E. Izokh , Peter A. Nevolko , Trong Hoa Tran , Hoàng Ly Vũ , Thi Phuong Ngo
{"title":"Indosinian magmatism in NE Vietnam: Petrogenesis and geodynamic implications of Triassic mafic suites from the Song Hien region","authors":"Thi Huong Ngo ,&nbsp;Tatyana V. Svetlitskaya ,&nbsp;Tuan Anh Tran ,&nbsp;Andrey E. Izokh ,&nbsp;Peter A. Nevolko ,&nbsp;Trong Hoa Tran ,&nbsp;Hoàng Ly Vũ ,&nbsp;Thi Phuong Ngo","doi":"10.1016/j.lithos.2024.107842","DOIUrl":"10.1016/j.lithos.2024.107842","url":null,"abstract":"<div><div>The Song Hien region is located at the southern margin of the South China Block and includes Early–Middle Triassic mafic suites. The petrogenesis and tectonic context of these rocks are important to comprehending one of the most challenging periods in the tectonic evolution of northern Vietnam related to the South China–Indochina collision. In the present study, we provide the first systematic examination of whole-rock geochemical and Sr<img>Nd isotopic compositions of mafic suites from the NE Vietnam. The studied Early–Middle Triassic suites are dominated by basalts. The rocks are enriched in LILEs, U, and Th and depleted in Nb and Ta and show a wide range of geochemical and Sr<img>Nd isotopic compositions ((La/Yb)<sub>CN</sub> = 0.4–4.6; Dy/Dy<sup>⁎</sup> = 0.7–1.3; (<sup>87</sup>Sr/<sup>86</sup>Sr)<em>i</em> = 0.7053–0.7125; <em>ε</em>Nd(t) = (+3.7)–(−8.0)). They all originated from shallow melting of a subduction-modified lithospheric mantle, and the compositional diversity of these basalts is attributed mainly to geochemical and Nd-isotopic heterogeneity in the mantle source. The geochemical and Sr<img>Nd isotopic features of the studied mafic suites indicate a negligible contribution of the asthenospheric mantle to magma generation and differ significantly from those of the Emeishan plume-related basalts. A model in which Early–Middle Triassic mafic magmatic activity in the NE Vietnam region is the result of decompression melting driven by convective thinning of the South China mantle lithosphere during the 250–240 Ma period is discussed in the study. This period corresponds to the South China–Indochina continental collision. In the NE Vietman region, the Early–Middle Triassic <em>syn</em>-collisional magmatism has an important metallogenic context, controlling Ni<img>Cu sulfide and Sn(<img>Cu) mineralizations.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"488 ","pages":"Article 107842"},"PeriodicalIF":2.9,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142551923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Nanoscale Os isotopic quantification of Wadi Tayin dunite platinum group minerals by atom probe tomography 利用原子探针断层扫描技术对瓦迪塔因白云石铂族矿物进行纳米级 Os 同位素定量分析
IF 2.9 2区 地球科学
Lithos Pub Date : 2024-10-24 DOI: 10.1016/j.lithos.2024.107841
Stefano Tenuta , Katy A. Evans , Steven M. Reddy , David W. Saxey , Tommaso Tacchetto , Denis Fougerouse , Xiao Sun
{"title":"Nanoscale Os isotopic quantification of Wadi Tayin dunite platinum group minerals by atom probe tomography","authors":"Stefano Tenuta ,&nbsp;Katy A. Evans ,&nbsp;Steven M. Reddy ,&nbsp;David W. Saxey ,&nbsp;Tommaso Tacchetto ,&nbsp;Denis Fougerouse ,&nbsp;Xiao Sun","doi":"10.1016/j.lithos.2024.107841","DOIUrl":"10.1016/j.lithos.2024.107841","url":null,"abstract":"<div><div>Serpentinites record processes that redistribute major and trace elements between mantle and crust. Platinum Group Elements (PGEs) are trace elements in serpentinites hosted in sulphides and alloys. Alloys are challenging to find, and most analytical techniques lack the spatial resolution to analyse them. This research adopts automatic mineral mapping technique to detect PGM grains in a sample from the Wadi Tayin (Oman) peridotite and uses atom probe tomography, a nanoscale quantitative analytical technique, to analyse the grain. This work applies and assesses the applicability of atom probe tomography to measure the <sup>187</sup>Os/<sup>188</sup>Os isotopic ratio of natural alloys and uses the ratio to constrain the source of Os. A novel algorithm is used to automatically determine the number of counts of the <sup>187</sup>Os and <sup>188</sup>Os peaks, to calculate the isotopic <sup>187</sup>Os/<sup>188</sup>Os ratio and the analytical uncertainty. The <sup>187</sup>Os/<sup>188</sup>Os ratio is 0.126 ± 0.003, consistent with the isotopic composition reported by literature in the dunite of the Main Mantle Section of the Wadi Tayin ophiolite.</div><div>The analytical uncertainty is one order of magnitude higher than conventional bulk rock techniques, such as negative-thermal ionisation mass spectrometry (N-TIMS) and inductively coupled plasma mass spectrometry (ICP-MS). However, the precision is sufficient to conclude that the non-radiogenic <sup>187</sup>Os/<sup>188</sup>Os ratio is compatible with a mantle origin for the alloy. Decreasing whole-rock Re with increasing LOI and the overprinting of magmatic pentlandite by magnetite demonstrate that progressive serpentinisation may have modified the Re budget. The results indicate that atom probe tomography can analyse <sup>187</sup>Os/<sup>188</sup>Os ratio quantitatively in micron-sized natural alloys and provide insights into natural processes.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"488 ","pages":"Article 107841"},"PeriodicalIF":2.9,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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