Chemie Der Erde-Geochemistry最新文献_第8页

Petrology and P-T evolution of high-grade garnet metabasites from the Tin Begane area (Laouni terrane, South Algeria) 阿尔及利亚南部Laouni地块Tin Begane地区高品位石榴石变质岩的岩石学及P-T演化

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Chemie Der Erde-Geochemistry

Pub Date : 2025-05-01 DOI: 10.1016/j.chemer.2025.126260

Amar Arab , Amel Bitam-Derridj , Khadidja Ouzegane , Gaston Godard , Sidali Doukkari

The south of the Tin Begane region (Laouni terrane, Central Hoggar, southern Algeria) has been subjected to high grade metamorphism and shows well-preserved relicts of garnet-bearing metabasites boudinaged within metapelites and migmatites. These rocks have preserved a number of spectacular mineral assemblages and reaction microstructures. Two successive metamorphic stages have been recognised, on the basis of metamorphic microstructures and mineral compositions: (i) the main primary paragenesis consists of garnet porphyroblasts, amphibole, clinopyroxene, titanite and quartz; (ii) the retrograde stage is evidenced by clinopyroxene-amphibole-plagioclase symplectites, which developed mainly at the expense of garnet, as well as peculiar clinopyroxene-ilmenite symplectites after titanite. Garnet porphyroblasts are almandine-grossular (Alm_46–58 Prp_7–14 Grs_28–42 Sps_1–5) and show a smooth zoning pattern from the core to the outer rim. The clinopyroxene is diopside but shows slight chemical variations depending on its microstructural position in the rock (inclusion in garnet: X_Fe = 0.39; Al_total = 0.06 apfu; Ca = 0.90 apfu; ameboid crystals in the matrix: X_Fe = 0.42–0.47; Al_total = 0.15–0.16 apfu; Ca = 0.90–0.93 apfu; clinopyroxene in symplectite: X_Fe = 0.37–0.52; Al_total = 0.06–0.11 apfu; Ca = 0.91–0.95 apfu). The amphibole is (ferro-)tchermackite to (ferro/magnesio)-hornblende, with some grains exhibiting a smooth chemical zoning profile from core to rim. Plagioclase, either from the main paragenesis or from the Cpx + Pl symplectites, is anorthite (X_An = 0.92–0.97). To reconstruct the pressure-temperature evolution of a selected sample, two P-T pseudosections were calculated in the NCKFMASHTO system. The first pseudosection was modelled using the bulk-rock composition of the sample, whereas the second was calculated for the overall composition of the late symplectites, estimated by balancing the reaction that produced them. The results indicate that the studied metabasites have experienced a clockwise P-T path, with a decompression from peak conditions estimated at 13–15 kbar and 750 ± 50 °C down to 7–4.5 kbar and 810 ± 50 °C. The clockwise P-T path can be interpreted in terms of crustal thickening followed by exhumation, most likely during the Pan-African orogenesis.

Tin Begane地区南部（阿尔及利亚南部Hoggar中部Laouni地体）经历了高变质作用，在变质岩和混辉岩之间发现了保存完好的含石榴石变质岩遗迹。这些岩石保存了许多壮观的矿物组合和反应微观结构。根据变质微观结构和矿物组成，确定了两个连续的变质阶段：(1)主要的原生共生由石榴石卟啉母岩、角闪孔、斜辉石、钛矿和石英组成；（ii）逆行期主要发育斜辉石-角闪石-斜长石共长岩，主要以石榴石为代价发育，在钛矿之后还发育了特殊的斜辉石-钛铁矿共长岩。石榴石卟啉母细胞为almandinine -grossular (Alm46-58 Prp7-14 Grs28-42 Sps1-5)，从核心到外缘呈光滑的分带模式。斜辉石为透辉石，但根据其在岩石中的显微结构位置(在石榴石中的包裹体：XFe = 0.39；Altotal = 0.06 apfu；Ca = 0.90 apfu；基体中阿米巴晶体：XFe = 0.42-0.47；Altotal = 0.15-0.16 apfu；Ca = 0.90-0.93 apfu；斜辉石：XFe = 0.37-0.52；Altotal = 0.06-0.11 apfu；Ca = 0.91-0.95 apfu)。角闪孔为（铁-）镁铁-（铁/镁）角闪石-（铁/镁）角闪石，部分颗粒从岩心到边缘呈光滑的化学分带剖面。斜长石为钙长石（XAn = 0.92-0.97），无论是来自主共生体还是来自Cpx + Pl合生体。为了重建选定样品的压力-温度演化，在NCKFMASHTO体系中计算了两个P-T伪截面。第一个伪剖面是使用样品的整体岩石组成来建模的，而第二个伪剖面是通过平衡产生它们的反应来计算晚期复合岩的整体组成。结果表明，所研究的变质岩经历了顺时针的P-T路径，减压从峰值条件估计为13-15 kbar和750±50°C下降到7-4.5 kbar和810±50°C。顺时针的P-T路径可以解释为地壳增厚之后的挖掘，最有可能是在泛非造山运动期间。

{"title":"Petrology and P-T evolution of high-grade garnet metabasites from the Tin Begane area (Laouni terrane, South Algeria)","authors":"Amar Arab , Amel Bitam-Derridj , Khadidja Ouzegane , Gaston Godard , Sidali Doukkari","doi":"10.1016/j.chemer.2025.126260","DOIUrl":"10.1016/j.chemer.2025.126260","url":null,"abstract":"<div><div>The south of the Tin Begane region (Laouni terrane, Central Hoggar, southern Algeria) has been subjected to high grade metamorphism and shows well-preserved relicts of garnet-bearing metabasites boudinaged within metapelites and migmatites. These rocks have preserved a number of spectacular mineral assemblages and reaction microstructures. Two successive metamorphic stages have been recognised, on the basis of metamorphic microstructures and mineral compositions: (i) the main primary paragenesis consists of garnet porphyroblasts, amphibole, clinopyroxene, titanite and quartz; (ii) the retrograde stage is evidenced by clinopyroxene-amphibole-plagioclase symplectites, which developed mainly at the expense of garnet, as well as peculiar clinopyroxene-ilmenite symplectites after titanite. Garnet porphyroblasts are almandine-grossular (Alm<sub>46–58</sub> Prp<sub>7–14</sub> Grs<sub>28–42</sub> Sps<sub>1–5</sub>) and show a smooth zoning pattern from the core to the outer rim. The clinopyroxene is diopside but shows slight chemical variations depending on its microstructural position in the rock (inclusion in garnet: <em>X</em><sub><em>Fe</em></sub> = 0.39; Al<sub>total</sub> = 0.06 apfu; Ca = 0.90 apfu; ameboid crystals in the matrix: <em>X</em><sub><em>Fe</em></sub> = 0.42–0.47; Al<sub>total</sub> = 0.15–0.16 apfu; Ca = 0.90–0.93 apfu; clinopyroxene in symplectite: <em>X</em><sub><em>Fe</em></sub> = 0.37–0.52; Al<sub>total</sub> = 0.06–0.11 apfu; Ca = 0.91–0.95 apfu). The amphibole is (ferro-)tchermackite to (ferro/magnesio)-hornblende, with some grains exhibiting a smooth chemical zoning profile from core to rim. Plagioclase, either from the main paragenesis or from the Cpx + Pl symplectites, is anorthite (<em>X</em><sub><em>An</em></sub> = 0.92–0.97). To reconstruct the pressure-temperature evolution of a selected sample, two <em>P-T</em> pseudosections were calculated in the NCKFMASHTO system. The first pseudosection was modelled using the bulk-rock composition of the sample, whereas the second was calculated for the overall composition of the late symplectites, estimated by balancing the reaction that produced them. The results indicate that the studied metabasites have experienced a clockwise <em>P-T</em> path, with a decompression from peak conditions estimated at 13–15 kbar and 750 ± 50 °C down to 7–4.5 kbar and 810 ± 50 °C. The clockwise <em>P-T</em> path can be interpreted in terms of crustal thickening followed by exhumation, most likely during the Pan-African orogenesis.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 2","pages":"Article 126260"},"PeriodicalIF":2.6,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144290771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Preface: “Geodynamic evolution and metallogeny of the Hoggar massif” 前言：“霍格尔地块地球动力学演化与成矿作用”

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Chemie Der Erde-Geochemistry

Pub Date : 2025-05-01 DOI: 10.1016/j.chemer.2025.126291

Torsten Graupner , Abderrahmane Bendaoud , Mohamed Hamoudi , Astrid Holzheid , Basem Zoheir , El-Hocine Fettous , Simon Goldmann

引用次数: 0

Nb-Ta-Sn oxides as markers of magmatic fractionation and magmatic-hydrothermal evolution: The example of the Nuweibi granite intrusion, Eastern Desert, Egypt 铌钽锡氧化物作为岩浆分馏和岩浆热液演化的标志——以埃及东部沙漠Nuweibi花岗岩侵入岩为例

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Chemie Der Erde-Geochemistry

Pub Date : 2025-05-01 DOI: 10.1016/j.chemer.2024.126215

Simon Goldmann , Julie Anne-Sophie Michaud , Torge Krummacker , Chao Zhang , François Holtz , Ali A. Khudeir , Sadeq Hamid , Mohamed Abu El-Rus

The Nuweibi rare-metal granite is located in the Central Eastern Desert of Egypt and represents a highly evolved leucogranite pluton that intruded into Neoproterozoic basement rocks of the Arabian-Nubian Shield. It is separated by the NNE-SSW trending oblique sinistral Dabr fault into two principal granite facies: a medium-grained albite granite in the western block and a porphyritic albite granite in the eastern block. The major ore minerals among the disseminated Nb-Ta-Sn mineralization are columbite-group minerals (CGM), wodginite, microlite, and cassiterite, which follow a distinct crystallization sequence including partial dissolution and late recrystallization. These ore minerals are usually strongly zoned, exhibiting a wide range of chemical compositions. As peculiarity, cm-sized euhedral columbite crystals with thin Ta-rich rims are found in the massive quartz cap of the eastern block of the intrusion. On the basis of mineral textures and microanalysis of mineral chemistry of the Nb-Ta-Sn oxides, we propose a genetic model for the evolution of the Nuweibi granitic intrusion involving magmatic, magmatic-hydrothermal, and subsolidus ore-forming processes: 1) upward migration of a granitic melt to the level of emplacement and fractional crystallization resulting in enrichment of the residual melt in incompatible elements (e.g., Ta, Nb, Sn) and volatiles (H₂O and F); 2) incipient magmatic crystallization of early Nb-rich CGM-1, albite, and snowball quartz and Ta enrichment in the melt (more incompatible than Nb); 3) onset of fluid exsolution (fluid saturation in the melt at the magmatic-hydrothermal transition), magmatic crystallization of CGM-2 with increasingly higher #Ta with co-existing fluid; 4) solidification of the quartz cap due to undercooling saturation with precipitation of columbite under hydrothermal conditions from magmatic fluids; 5) late magmatic fluid circulation, dissolution of the CGM and re-precipitation of CGM-3, followed by late-stage wodginite and microlite; 6) oblique sinistral and normal faulting after solidification of the Nuweibi granite, leading to the western block of the intrusion to move diagonally upwards resulting in today's opposing levels of exposure. As a result, the mineral paragenesis, texture, and mineral chemistry of Nb-Ta-Sn minerals prove to be remarkable tracers of the evolution from magmatic to hydrothermal conditions in rare-metal granites.

努韦比稀有金属花岗岩位于埃及沙漠中东部，是侵入阿拉伯-努比亚盾新元古代基底岩的高度演化的浅花岗岩体。北北-南西向的斜左旋Dabr断裂将其分隔为两个主要的花岗岩相：西部块体的中粒钠长花岗岩和东部块体的斑状钠长花岗岩。浸染型铌钽锡矿化的主要矿石矿物为柱状矿群矿物（CGM）、木柳矿、微岩和锡石，具有明显的部分溶蚀和晚期再结晶的结晶顺序。这些矿石矿物通常有很强的分带性，表现出广泛的化学成分。在侵入体东部地块块状石英盖层中，奇特地发现了cm大小的自面体柱状晶体，具有薄的富ta边缘。基于矿物结构和微量矿物化学分析，本文提出了Nuweibi花岗岩体演化的成因模式，包括岩浆、岩浆-热液和亚固体成矿过程：1)花岗岩体熔体向上迁移至侵位水平，分异结晶导致残余熔体中不相容元素（如Ta、Nb、Sn）和挥发物（H2O和F）富集；2)早期富铌的CGM-1、钠长石和雪球石英的早期岩浆结晶与熔体中富集的Ta（比Nb更不相容）；(3)岩浆-热液过渡阶段熔体流体饱和度开始，ggm -2岩浆结晶，Ta值越来越高，流体共存；4)岩浆热液条件下柱状体沉淀导致石英帽过冷饱和凝固；5)晚期岩浆流体循环，CGM溶蚀，CGM-3再沉淀，其次是晚期的木质岩和微岩；(6) Nuweibi花岗岩凝固后的斜左、正断裂，导致岩体西块体对角向上移动，形成了今天相反的暴露水平。结果表明，铌钽锡矿物的共生、结构和矿物化学特征是稀有金属花岗岩从岩浆到热液演化的重要示踪剂。

{"title":"Nb-Ta-Sn oxides as markers of magmatic fractionation and magmatic-hydrothermal evolution: The example of the Nuweibi granite intrusion, Eastern Desert, Egypt","authors":"Simon Goldmann , Julie Anne-Sophie Michaud , Torge Krummacker , Chao Zhang , François Holtz , Ali A. Khudeir , Sadeq Hamid , Mohamed Abu El-Rus","doi":"10.1016/j.chemer.2024.126215","DOIUrl":"10.1016/j.chemer.2024.126215","url":null,"abstract":"<div><div>The Nuweibi rare-metal granite is located in the Central Eastern Desert of Egypt and represents a highly evolved leucogranite pluton that intruded into Neoproterozoic basement rocks of the Arabian-Nubian Shield. It is separated by the NNE-SSW trending oblique sinistral Dabr fault into two principal granite facies: a medium-grained albite granite in the western block and a porphyritic albite granite in the eastern block. The major ore minerals among the disseminated Nb-Ta-Sn mineralization are columbite-group minerals (CGM), wodginite, microlite, and cassiterite, which follow a distinct crystallization sequence including partial dissolution and late recrystallization. These ore minerals are usually strongly zoned, exhibiting a wide range of chemical compositions. As peculiarity, cm-sized euhedral columbite crystals with thin Ta-rich rims are found in the massive quartz cap of the eastern block of the intrusion. On the basis of mineral textures and microanalysis of mineral chemistry of the Nb-Ta-Sn oxides, we propose a genetic model for the evolution of the Nuweibi granitic intrusion involving magmatic, magmatic-hydrothermal, and subsolidus ore-forming processes: 1) upward migration of a granitic melt to the level of emplacement and fractional crystallization resulting in enrichment of the residual melt in incompatible elements (e.g., Ta, Nb, Sn) and volatiles (H<sub>2</sub>O and F); 2) incipient magmatic crystallization of early Nb-rich CGM-1, albite, and snowball quartz and Ta enrichment in the melt (more incompatible than Nb); 3) onset of fluid exsolution (fluid saturation in the melt at the magmatic-hydrothermal transition), magmatic crystallization of CGM-2 with increasingly higher #Ta with co-existing fluid; 4) solidification of the quartz cap due to undercooling saturation with precipitation of columbite under hydrothermal conditions from magmatic fluids; 5) late magmatic fluid circulation, dissolution of the CGM and re-precipitation of CGM-3, followed by late-stage wodginite and microlite; 6) oblique sinistral and normal faulting after solidification of the Nuweibi granite, leading to the western block of the intrusion to move diagonally upwards resulting in today's opposing levels of exposure. As a result, the mineral paragenesis, texture, and mineral chemistry of Nb-Ta-Sn minerals prove to be remarkable tracers of the evolution from magmatic to hydrothermal conditions in rare-metal granites.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 2","pages":"Article 126215"},"PeriodicalIF":2.6,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144290643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Petrogenetic and dynamic links between felsic and mafic magmas: Insights from the Devonian post-collisional magmatism in the North Qaidam terrane, western China 柴达木北缘泥盆系碰撞后岩浆活动的启示——长英质岩浆与镁质岩浆的成因与动力学联系

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Chemie Der Erde-Geochemistry

Pub Date : 2025-04-28 DOI: 10.1016/j.chemer.2025.126298

Denghui Chen , Hao Wu , Dongdong Yan , Chengxiang Li , Huajun Wen , Fuhao Xiong

Felsic-mafic magmatism in post-collisional settings provides valuable insights into the growth and evolution of continental crust, but the interaction processes between felsic and mafic magmatism and their implications for the diversity of igneous rocks remain controversial. This study presents petrological, geochronological, geochemical, and Sr-Nd-Hf isotopic analyses of the Mohe felsic-mafic complex, a rare post-collisional composite pluton in the North Qaidam terrane (western China), to investigate the petrogenetic and dynamic links between felsic and mafic magmas. The results reveal that the Mohe complex, consisting of granite, granodiorite, diorite, and appinites, is genetically related and formed between ca. 408–400 Ma. The granites and granodiorites are classified as I-type and are characterized by enriched isotopic signatures, including whole-rock (⁸⁷Sr/⁸⁶Sr)ᵢ values of 0.714584–0.728765, εNd_{(400 Ma)} values of −7.75 to −5.56, and zircon εHf(t) values of −3.04 to −0.28. These rocks were primarily derived from partial melting of Mesoproterozoic to Paleoproterozoic crustal materials, with minor input from a mantle source. The appinites display depleted zircon Hf isotopic compositions (εHf(t) = +4.10 to +5.71), indicating derivation from an OIB-like depleted mantle source that was metasomatized by subducted slab-derived melts. The diorites show weakly enriched isotopes ((⁸⁷Sr/⁸⁶Sr)_i = 0.709358–0.713210, εNd_{(400 Ma)} = −2.99 to −2.73, εHf(t) = −1.35 to +3.54), and were formed by the mixing of 80–90 % appinitic magma with 10–20 % crustal-derived granitic magma. Our findings suggest that the Early Devonian magmatism in the North Qaidam terrane was likely driven by slab break-off-related geodynamic processes, where crust-mantle magma mixing, along with mineral accumulation and fractional crystallization, played a key role in the petrological diversity of the continental crust in a post-collisional extensional setting.

后碰撞环境下的长英-镁质岩浆作用为大陆地壳的生长演化提供了有价值的见解，但长英-镁质岩浆作用的相互作用过程及其对火成岩多样性的影响仍然存在争议。本文对柴达木北缘罕见的碰撞后复合岩体漠河长英基杂岩进行了岩石学、年代学、地球化学和Sr-Nd-Hf同位素分析，探讨了长英基岩浆与镁基岩浆的成因和动力学联系。结果表明，由花岗岩、花岗闪长岩、闪长岩和斜长岩组成的磨河杂岩形成于408 ~ 400 Ma之间，具有一定的成因关系。花岗岩和花岗闪长岩均为i型，具有丰富的同位素特征，全岩(87Sr/86Sr) ε值为0.714584 ~ 0.728765,εNd（400 Ma）值为−7.75 ~−5.56，锆石εHf(t)值为−3.04 ~−0.28。这些岩石主要来自中元古代至古元古代地壳物质的部分熔融，少量来自地幔源的输入。斜长岩显示贫锆石Hf同位素组成（εHf(t) = +4.10 ~ +5.71），表明其源自类似obb的贫地幔源，由俯冲的板源熔体交代。闪长岩呈弱富集同位素((87Sr/86Sr)i = 0.709358 ~ 0.713210, εNd(400 Ma) = - 2.99 ~ - 2.73, εHf(t) = - 1.35 ~ +3.54)，由80 ~ 90%的辉长岩岩浆与10 ~ 20%的壳源花岗质岩浆混合形成。研究结果表明，柴达木北缘早泥盆世岩浆活动可能是由板块断裂相关的地球动力学过程驱动的，壳幔岩浆混合、矿物聚集和分离结晶对碰撞后伸展环境下大陆地壳岩石学多样性起着关键作用。

{"title":"Petrogenetic and dynamic links between felsic and mafic magmas: Insights from the Devonian post-collisional magmatism in the North Qaidam terrane, western China","authors":"Denghui Chen , Hao Wu , Dongdong Yan , Chengxiang Li , Huajun Wen , Fuhao Xiong","doi":"10.1016/j.chemer.2025.126298","DOIUrl":"10.1016/j.chemer.2025.126298","url":null,"abstract":"<div><div>Felsic-mafic magmatism in post-collisional settings provides valuable insights into the growth and evolution of continental crust, but the interaction processes between felsic and mafic magmatism and their implications for the diversity of igneous rocks remain controversial. This study presents petrological, geochronological, geochemical, and Sr-Nd-Hf isotopic analyses of the Mohe felsic-mafic complex, a rare post-collisional composite pluton in the North Qaidam terrane (western China), to investigate the petrogenetic and dynamic links between felsic and mafic magmas. The results reveal that the Mohe complex, consisting of granite, granodiorite, diorite, and appinites, is genetically related and formed between ca. 408–400 Ma. The granites and granodiorites are classified as I-type and are characterized by enriched isotopic signatures, including whole-rock (<sup>87</sup>Sr/<sup>86</sup>Sr)ᵢ values of 0.714584–0.728765, εNd<sub>(400 Ma)</sub> values of −7.75 to −5.56, and zircon εHf(t) values of −3.04 to −0.28. These rocks were primarily derived from partial melting of Mesoproterozoic to Paleoproterozoic crustal materials, with minor input from a mantle source. The appinites display depleted zircon Hf isotopic compositions (εHf(t) = +4.10 to +5.71), indicating derivation from an OIB-like depleted mantle source that was metasomatized by subducted slab-derived melts. The diorites show weakly enriched isotopes ((<sup>87</sup>Sr/<sup>86</sup>Sr)<sub><em>i</em></sub> = 0.709358–0.713210, εNd<sub>(400 Ma)</sub> = −2.99 to −2.73, εHf(t) = −1.35 to +3.54), and were formed by the mixing of 80–90 % appinitic magma with 10–20 % crustal-derived granitic magma. Our findings suggest that the Early Devonian magmatism in the North Qaidam terrane was likely driven by slab break-off-related geodynamic processes, where crust-mantle magma mixing, along with mineral accumulation and fractional crystallization, played a key role in the petrological diversity of the continental crust in a post-collisional extensional setting.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126298"},"PeriodicalIF":2.6,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143911631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Enhanced analysis of hydrothermal alteration and mineral prospecting through integration of ASTER and aeroradiometric data: A case study from the Ouarzazate region, Morocco 结合ASTER和航空辐射数据加强热液蚀变分析和找矿：以摩洛哥瓦尔扎扎特地区为例

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Chemie Der Erde-Geochemistry

Pub Date : 2025-04-26 DOI: 10.1016/j.chemer.2025.126296

Ilham El Hakimi, Lahsen Achkouch, Younesse El Cheikh, Mohammad Taadid, Houda Bourouda, Ahmed Rachid, Ahmed Attou

The study area, situated in the western segment of the Saghro Massif within the Anti-Atlas belt, is characterized by mineralized deposits, intricate lithological formations, and distinctive tectonic features. This research integrates ASTER imagery analysis with gamma-ray spectrometry data to map alteration zones and examine the geochemical and mineralogical processes that influence radioactive element distribution. Specific analytical techniques are applied to investigate relationships among argillic, phyllic, propylitic alterations, iron oxides, and regions with elevated concentrations of radiometric elements. Gamma-ray spectrometry data, including mono-elemental maps of radiometric components (potassium in %, equivalent uranium in ppm, and equivalent thorium in ppm), are analyzed alongside interpreted ASTER images to identify potential mineralization zones. Ratios of K/eU and K/eTh, along with the F parameter, are processed within a fuzzy model framework, which combines these datasets into a comprehensive mineral prospectivity map that serves as a tool for guiding exploration. This analysis identifies four hydrothermal alteration zones as highly promising for mineral exploration, suggesting a likely association between magmatic processes and spatially correlated hydrothermal alteration, thereby supporting further detailed exploration initiatives.

研究区位于反阿特拉斯带内的萨格罗地块西段，矿床成矿，岩性构造复杂，构造特征鲜明。该研究将ASTER图像分析与伽马射线能谱数据相结合，绘制蚀变带，并检查影响放射性元素分布的地球化学和矿物学过程。特定的分析技术被应用于研究胶、叶基、丙基变化、氧化铁和辐射元素浓度升高区域之间的关系。伽马射线能谱数据，包括辐射成分的单元素图（钾%，当量铀ppm，当量钍ppm），与解释的ASTER图像一起进行分析，以确定潜在的矿化带。K/eU和K/eTh的比率以及F参数在模糊模型框架内进行处理，该模型框架将这些数据集组合成综合的矿产远景图，作为指导勘探的工具。该分析确定了四个极具矿产勘探前景的热液蚀变带，表明岩浆过程与空间相关性热液蚀变之间可能存在关联，从而支持进一步详细的勘探活动。

{"title":"Enhanced analysis of hydrothermal alteration and mineral prospecting through integration of ASTER and aeroradiometric data: A case study from the Ouarzazate region, Morocco","authors":"Ilham El Hakimi, Lahsen Achkouch, Younesse El Cheikh, Mohammad Taadid, Houda Bourouda, Ahmed Rachid, Ahmed Attou","doi":"10.1016/j.chemer.2025.126296","DOIUrl":"10.1016/j.chemer.2025.126296","url":null,"abstract":"<div><div>The study area, situated in the western segment of the Saghro Massif within the Anti-Atlas belt, is characterized by mineralized deposits, intricate lithological formations, and distinctive tectonic features. This research integrates ASTER imagery analysis with gamma-ray spectrometry data to map alteration zones and examine the geochemical and mineralogical processes that influence radioactive element distribution. Specific analytical techniques are applied to investigate relationships among argillic, phyllic, propylitic alterations, iron oxides, and regions with elevated concentrations of radiometric elements. Gamma-ray spectrometry data, including mono-elemental maps of radiometric components (potassium in %, equivalent uranium in ppm, and equivalent thorium in ppm), are analyzed alongside interpreted ASTER images to identify potential mineralization zones. Ratios of K/eU and K/eTh, along with the F parameter, are processed within a fuzzy model framework, which combines these datasets into a comprehensive mineral prospectivity map that serves as a tool for guiding exploration. This analysis identifies four hydrothermal alteration zones as highly promising for mineral exploration, suggesting a likely association between magmatic processes and spatially correlated hydrothermal alteration, thereby supporting further detailed exploration initiatives.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126296"},"PeriodicalIF":2.6,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143883029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Geochemistry, zircon UPb ages and Hf isotopes of Tra Bong granitoid from Kontum massif, central Vietnam, and its petrogenetic significance 越南中部Kontum地块特拉峰花岗岩的地球化学、锆石UPb年龄和Hf同位素特征及其成岩意义

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Chemie Der Erde-Geochemistry

Pub Date : 2025-04-25 DOI: 10.1016/j.chemer.2025.126295

Nguyen Huu Trong , Pham Trung Hieu , Pham Minh , Bui Kim Ngoc , Nguyen Dinh Luyen , To Xuan Ban

Tra Bong granitoid, distributed in the northern area of Kontum, primarily consists of diorite and granodiorite. The main rock-forming minerals contain plagioclase (26–60 %), K-feldspar (8–22 %), quartz (15–33 %), biotite (3–7 %), and hornblende (9–20 %). The accessory minerals are sphene, apatite, zircon, and magnetite. Tra Bong granitoids are characterized by SiO₂ (58.83–65.8 %), total alkali (6.68–8.03 %), and A/CNK (0.80–0.90). They show high-K and relative enrichment of large-ion lithophile elements (Sc, Rb, and K), and the relative depletion of Nb, Ta, and Ti elements. The P₂O₅ content decreases with increasing SiO₂, and Th increases with Rb, a trend typical of I-type granites. All observed petrographic and geochemical characteristics suggested that the Tra Bong granitoid is typical of the I-type granite, formed in a subduction zone. The UPb crystallization age ranges from 254.5 to 255.0 Ma, coinciding with the Late Permian-Early Triassic magmatic activity, which was previously reported in the Truong Son belt. The ε_Hf(t) value together with the Hf zircon model ages (T_DM2) ranges from 1011 to 1159 Ma. The Tra Bong granitoid is a result of partial melting Mesoproterozoic mafic-intermediate magmatic rocks, with a minor amount of metasedimentary crust remelting. In conjunction with other Permian-Triassic magmatic rocks along Truong Son belt and the Song Ma suture, the Tra Bong granitoid represents magmatic activity related to subduction-collision of the Indochina and South China blocks and closure of Paleo-Tethys Ocean in the Late Permian-Early Triassic, along the Song Ma suture.

特拉峰花岗岩类主要由闪长岩和花岗闪长岩组成，分布于孔图姆北部地区。主要造岩矿物有斜长石（26 - 60%）、钾长石（8 - 22%）、石英（15 - 33%）、黑云母（3 - 7%）和角闪石（9 - 20%）。副矿物为榍石、磷灰石、锆石、磁铁矿。以SiO2（58.83 ~ 65.8%）、总碱（6.68 ~ 8.03%）、A/CNK（0.80 ~ 0.90）为主要特征。大离子亲石元素（Sc、Rb和K）相对富集，Nb、Ta和Ti元素相对富集。P2O5含量随SiO2的增加而降低，Th含量随Rb的增加而增加，呈典型的i型花岗岩特征。岩石学和地球化学特征表明，特拉峰花岗岩属典型的i型花岗岩，形成于俯冲带。UPb结晶年龄为254.5 ~ 255.0 Ma，与早二叠世—早三叠世的岩浆活动相吻合。εHf(t)值与Hf锆石模型年龄（TDM2）的变化范围为1011 ~ 1159 Ma。特拉峰花岗岩类是中元古代基性-中岩浆岩浆岩部分熔融的产物，并伴有少量的变质沉积岩壳重熔。特拉峰花岗岩类与张松带及松马缝合带上其他二叠系—三叠纪岩浆岩相结合，代表了晚二叠世—早三叠世沿松马缝合带上印度支那和华南陆块俯冲碰撞及古特提斯洋闭合相关的岩浆活动。

{"title":"Geochemistry, zircon UPb ages and Hf isotopes of Tra Bong granitoid from Kontum massif, central Vietnam, and its petrogenetic significance","authors":"Nguyen Huu Trong , Pham Trung Hieu , Pham Minh , Bui Kim Ngoc , Nguyen Dinh Luyen , To Xuan Ban","doi":"10.1016/j.chemer.2025.126295","DOIUrl":"10.1016/j.chemer.2025.126295","url":null,"abstract":"<div><div>Tra Bong granitoid, distributed in the northern area of Kontum, primarily consists of diorite and granodiorite. The main rock-forming minerals contain plagioclase (26–60 %), K-feldspar (8–22 %), quartz (15–33 %), biotite (3–7 %), and hornblende (9–20 %). The accessory minerals are sphene, apatite, zircon, and magnetite. Tra Bong granitoids are characterized by SiO<sub>2</sub> (58.83–65.8 %), total alkali (6.68–8.03 %), and A/CNK (0.80–0.90). They show high-K and relative enrichment of large-ion lithophile elements (Sc, Rb, and K), and the relative depletion of Nb, Ta, and Ti elements. The P<sub>2</sub>O<sub>5</sub> content decreases with increasing SiO<sub>2</sub>, and Th increases with Rb, a trend typical of I-type granites. All observed petrographic and geochemical characteristics suggested that the Tra Bong granitoid is typical of the I-type granite, formed in a subduction zone. The U<img>Pb crystallization age ranges from 254.5 to 255.0 Ma, coinciding with the Late Permian-Early Triassic magmatic activity, which was previously reported in the Truong Son belt. The ε<sub>Hf</sub>(t) value together with the Hf zircon model ages (T<sub>DM2</sub>) ranges from 1011 to 1159 Ma. The Tra Bong granitoid is a result of partial melting Mesoproterozoic mafic-intermediate magmatic rocks, with a minor amount of metasedimentary crust remelting. In conjunction with other Permian-Triassic magmatic rocks along Truong Son belt and the Song Ma suture, the Tra Bong granitoid represents magmatic activity related to subduction-collision of the Indochina and South China blocks and closure of Paleo-Tethys Ocean in the Late Permian-Early Triassic, along the Song Ma suture.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126295"},"PeriodicalIF":2.6,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143895853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Identifying geochemical element distribution patterns through multiple-point geostatistical simulation and singularity analysis: A case study of the Wulonggou-Balong Area, Qinghai, China 基于多点地质统计模拟和奇异性分析的地球化学元素分布模式识别——以青海乌龙沟-巴龙地区为例

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Chemie Der Erde-Geochemistry

Pub Date : 2025-04-19 DOI: 10.1016/j.chemer.2025.126294

Mengyu Zhao , Qinglin Xia , Wenjun Li

The identification of geochemical element distribution patterns, the extraction of anomalies from geochemical exploration data, and the analysis of deep-level mineralization information are essential to guiding mineral prospectivity mapping. The spatial distribution of geochemical elements mainly arises from complex geological processes, making it challenging for standard deterministic interpolation techniques to capture its complex structure. In singularity analysis of element distribution, the size and geometric configuration of the sliding window significantly impact the geochemical anomaly distribution. Accordingly, this study incorporated the complex patterns extracted from multi-scale exploration geochemical data into a multiple-point geostatistical simulation framework to characterize geochemical element distributions at a fine scale. Fractal topography and singularity analysis were integrated as key analytical tools to identify and extract anisotropic geochemical anomalies. Stream sediment geochemical data from the Wulonggou–Balong area, Qinghai, China, were used as a case study to delineate gold-related geochemical spatial distribution patterns. The proposed multiple-point geostatistical (MPS) method enhanced anomaly intensity in local regions while achieving higher fidelity in reproducing spatial distribution patterns that align with regional geological trends. The spatial distribution patterns of geochemical anomalies, analyzed through diverse fractal topological relationships, highlight anisotropic characteristics in geochemical element distributions governed by ore-controlling factors. Practical application demonstrated that the methods effectively identify undetected weak anomalies associated with mineralization-favorable zones within gold geochemical distribution patterns and minimize uncertainty in anomaly interpretation.

地球化学元素分布规律识别、化探异常提取、深部成矿信息分析是指导找矿填图的重要内容。地球化学元素的空间分布主要来源于复杂的地质过程，这使得标准的确定性插值技术难以捕捉其复杂的结构。在元素分布的奇异性分析中，滑动窗口的大小和几何构型对地球化学异常分布有显著影响。为此，本研究将多尺度勘查地球化学数据提取的复杂模式整合到多点地统计模拟框架中，以精细尺度表征地球化学元素的分布特征。将分形形貌与奇异性分析相结合，作为识别和提取地球化学各向异性异常的关键分析工具。以青海乌龙沟-巴龙地区水系沉积物地球化学资料为例，圈定了与金相关的地球化学空间分布格局。提出的多点地质统计（MPS）方法增强了局部区域的异常强度，同时在再现与区域地质趋势一致的空间分布格局方面实现了更高的保真度。通过不同的分形拓扑关系分析地球化学异常的空间分布规律，突出了控矿因素支配下地球化学元素分布的各向异性特征。实际应用表明，该方法能有效识别出金地球化学分布格局中与成矿有利带相关的未被发现的弱异常，并将异常解释的不确定性降至最低。

{"title":"Identifying geochemical element distribution patterns through multiple-point geostatistical simulation and singularity analysis: A case study of the Wulonggou-Balong Area, Qinghai, China","authors":"Mengyu Zhao , Qinglin Xia , Wenjun Li","doi":"10.1016/j.chemer.2025.126294","DOIUrl":"10.1016/j.chemer.2025.126294","url":null,"abstract":"<div><div>The identification of geochemical element distribution patterns, the extraction of anomalies from geochemical exploration data, and the analysis of deep-level mineralization information are essential to guiding mineral prospectivity mapping. The spatial distribution of geochemical elements mainly arises from complex geological processes, making it challenging for standard deterministic interpolation techniques to capture its complex structure. In singularity analysis of element distribution, the size and geometric configuration of the sliding window significantly impact the geochemical anomaly distribution. Accordingly, this study incorporated the complex patterns extracted from multi-scale exploration geochemical data into a multiple-point geostatistical simulation framework to characterize geochemical element distributions at a fine scale. Fractal topography and singularity analysis were integrated as key analytical tools to identify and extract anisotropic geochemical anomalies. Stream sediment geochemical data from the Wulonggou–Balong area, Qinghai, China, were used as a case study to delineate gold-related geochemical spatial distribution patterns. The proposed multiple-point geostatistical (MPS) method enhanced anomaly intensity in local regions while achieving higher fidelity in reproducing spatial distribution patterns that align with regional geological trends. The spatial distribution patterns of geochemical anomalies, analyzed through diverse fractal topological relationships, highlight anisotropic characteristics in geochemical element distributions governed by ore-controlling factors. Practical application demonstrated that the methods effectively identify undetected weak anomalies associated with mineralization-favorable zones within gold geochemical distribution patterns and minimize uncertainty in anomaly interpretation.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126294"},"PeriodicalIF":2.6,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Geochronology and petrogenesis of magmatic and high-grade metamorphic rocks in the Eocene Chapedony core complex: New insights into the basement geology of Iran 始新世Chapedony岩浆岩和高变质岩的年代学和岩石成因：伊朗基底地质的新认识

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Chemie Der Erde-Geochemistry

Pub Date : 2025-04-11 DOI: 10.1016/j.chemer.2025.126290

Zeynab Gharamohammadi , Peter A. Cawood , Ali Kananian , Reza Nozaem , Yona Jacobsen , David Lentz , Jafar Omrani

<div><div>The Arabia-Eurasia convergence zone provides an evolving record from oblique subduction to continental collision resulting in multiple transient tectonothermal events. Although the subduction of the Neotethys below the Iranian terranes and its relation to the arc and back-arc magmatism throughout the late Mesozoic and Cenozoic in Iran has been documented, the detailed geochemical and isotopic transition from subduction to back-arc extension was not constrained. This study reports the first evidence into the petrogenesis of magmatic diversity of Chapedony core complex (CCC) and the coexistence of Nb-enriched rocks and adakite-like rocks as a result of old crustal recycling. Integrated study of petrography, whole-rock major- and trace-element geochemical data supported with Sr and Nd isotope compositions, zircon U<img>Pb and traces, and zircon Hf isotope analyses reveal a protracted and pulsed evolution of the CCC. The complex consists of leucosome-bearing gabbro-diorite-granodiorite, quartz diorite, and biotite granite that formed between 50 and 40 Ma, but contains amphibolite (metabasite) bodies with zircon cores yielding U<img>Pb ages of 518 Ma and 189 Ma with MORB- and OIB-like characteristics, respectively. Biotite granites are divisible into two types; Type 1 have zircons with a wide range ages, while Type 2 are biotite granites with Eocene ages and lack inherited zircons. Biotite granites Type 1 yield a range of zircon ages (45–3200 Ma) with the youngest magmatic ages late Neoproterozoic-Early Cambrian, Triassic (240 Ma), and Eocene (48 Ma). εHf (t) values for zircon grains range from −23.95 to 13.13 for biotite granites (Type 1), −4.76 to 6.78 for amphibolites, and − 6.25 to 6.96 for Eocene mafic-felsic rock units. Biotite granites (Type 1) have I<sub>Sr</sub> and εNd values ranging from 0.7177 to 0.7308 and − 14.8 to −7.4, respectively, whereas these values for the amphibolites are 0.7056 to 0.7090 and − 4.4 to 11.3, respectively. The mid-Eocene rock units of the CCC have I<sub>Sr</sub> of 0.7050 to 0.7136 and εNd values of −3.9 to 8.9 gabbro-diorite-granodiorite, 3.3 to 16.3 for quartz diorite, and − 5.3 to −0.9 biotite granite (Type 2). The recorded zircon Hf isotopes along with I<sub>Sr</sub> and εNd values indicate that a hybrid and old mantle (MORB+OIB) previously metasomatised by subduction of old enriched components (biotite granite Type 1) into the mantle, predating Eocene appinite-like mafic magma generation. Subsequent partial melts of such a source generate Eocene appinite magmas, as transitional rocks, which evolved to Eocene intermediate-felsic rocks through magma-crust interaction and accumulation/fractionation after the initial melts formed in the lower crust. The timing of the CCC formation (50–40 Ma) corresponds to an amphibolite metamorphism involving temperatures of 600–800 °C, associated with partial melting during the regional back-arc extension. The formation of new crust, through the reactivation and recycl

阿拉伯-欧亚辐合带提供了一个从斜向俯冲到大陆碰撞的演化记录，导致了多次瞬变构造热事件。虽然新特提斯系在伊朗地体下的俯冲作用及其与整个晚中生代和新生代伊朗弧后岩浆活动的关系已被记录，但从俯冲到弧后伸展的详细地球化学和同位素转变并未受到限制。本文首次发现了Chapedony岩心杂岩（CCC）岩浆多样性的成因，以及古地壳再循环作用下富铌岩与埃达克岩类岩石共存的证据。综合岩石学研究、全岩主微量元素地球化学数据、Sr和Nd同位素组成、锆石UPb和微量元素、锆石Hf同位素分析等，揭示了CCC的长期和脉冲演化。该杂岩由含亮色体的辉长闪长花岗岩、石英闪长岩和黑云母花岗岩组成，形成于50 ~ 40 Ma之间，但含有角闪岩（变长岩）体，其锆石核的UPb年龄分别为518 Ma和189 Ma，具有MORB-和oib -类特征。黑云母花岗岩可分为两类；类型1锆石年龄范围广，类型2为始新世黑云母花岗岩，缺乏继承锆石。1型黑云母花岗岩的锆石年龄范围为45 ~ 3200 Ma，最年轻的岩浆年龄为新元古代-早寒武世晚期、三叠纪（240 Ma）和始新世（48 Ma）。1型黑云母花岗岩的锆石εHf (t)值为- 23.95 ~ 13.13，角闪岩的εHf (t)值为- 4.76 ~ 6.78，始新世基性-长英质岩石单元的εHf (t)值为- 6.25 ~ 6.96。黑云母花岗岩（1型）的ISr和εNd值分别为0.7177 ~ 0.7308和- 14.8 ~ - 7.4，角闪岩的ISr和εNd值分别为0.7056 ~ 0.7090和- 4.4 ~ 11.3。中始新统岩石单位的ISr为0.7050 ~ 0.7136，εNd值为−3.9 ~ 8.9，石英闪长岩为3.3 ~ 16.3，黑云母花岗岩为−5.3 ~−0.9（2型）。锆石Hf同位素记录以及ISr和εNd值表明，早于始新统类斜长岩基性岩浆的产生，锆石Hf同位素记录表明，一个混合的古老地幔（MORB+OIB）曾被古老的富集成分（1型黑云母花岗岩）俯冲到地幔中而发生交代作用。该源区后续部分熔体形成始新世斜长岩，作为过渡性岩石，下地壳初始熔体形成后，经岩浆-地壳相互作用和聚集/分馏作用演化为始新世中英质岩石。CCC的形成时间（50-40 Ma）对应于600-800°C的角闪岩变质作用，与区域弧后伸展期间的部分熔融有关。古冈瓦纳地壳的活化和再循环，以及过渡性岩浆的产生，可能是软流圈上升流和弧后伸展所引发的。这发生在新特提斯洋俯冲期间俯冲板块的后退之后，可能早于向碰撞过渡。

{"title":"Geochronology and petrogenesis of magmatic and high-grade metamorphic rocks in the Eocene Chapedony core complex: New insights into the basement geology of Iran","authors":"Zeynab Gharamohammadi , Peter A. Cawood , Ali Kananian , Reza Nozaem , Yona Jacobsen , David Lentz , Jafar Omrani","doi":"10.1016/j.chemer.2025.126290","DOIUrl":"10.1016/j.chemer.2025.126290","url":null,"abstract":"<div><div>The Arabia-Eurasia convergence zone provides an evolving record from oblique subduction to continental collision resulting in multiple transient tectonothermal events. Although the subduction of the Neotethys below the Iranian terranes and its relation to the arc and back-arc magmatism throughout the late Mesozoic and Cenozoic in Iran has been documented, the detailed geochemical and isotopic transition from subduction to back-arc extension was not constrained. This study reports the first evidence into the petrogenesis of magmatic diversity of Chapedony core complex (CCC) and the coexistence of Nb-enriched rocks and adakite-like rocks as a result of old crustal recycling. Integrated study of petrography, whole-rock major- and trace-element geochemical data supported with Sr and Nd isotope compositions, zircon U<img>Pb and traces, and zircon Hf isotope analyses reveal a protracted and pulsed evolution of the CCC. The complex consists of leucosome-bearing gabbro-diorite-granodiorite, quartz diorite, and biotite granite that formed between 50 and 40 Ma, but contains amphibolite (metabasite) bodies with zircon cores yielding U<img>Pb ages of 518 Ma and 189 Ma with MORB- and OIB-like characteristics, respectively. Biotite granites are divisible into two types; Type 1 have zircons with a wide range ages, while Type 2 are biotite granites with Eocene ages and lack inherited zircons. Biotite granites Type 1 yield a range of zircon ages (45–3200 Ma) with the youngest magmatic ages late Neoproterozoic-Early Cambrian, Triassic (240 Ma), and Eocene (48 Ma). εHf (t) values for zircon grains range from −23.95 to 13.13 for biotite granites (Type 1), −4.76 to 6.78 for amphibolites, and − 6.25 to 6.96 for Eocene mafic-felsic rock units. Biotite granites (Type 1) have I<sub>Sr</sub> and εNd values ranging from 0.7177 to 0.7308 and − 14.8 to −7.4, respectively, whereas these values for the amphibolites are 0.7056 to 0.7090 and − 4.4 to 11.3, respectively. The mid-Eocene rock units of the CCC have I<sub>Sr</sub> of 0.7050 to 0.7136 and εNd values of −3.9 to 8.9 gabbro-diorite-granodiorite, 3.3 to 16.3 for quartz diorite, and − 5.3 to −0.9 biotite granite (Type 2). The recorded zircon Hf isotopes along with I<sub>Sr</sub> and εNd values indicate that a hybrid and old mantle (MORB+OIB) previously metasomatised by subduction of old enriched components (biotite granite Type 1) into the mantle, predating Eocene appinite-like mafic magma generation. Subsequent partial melts of such a source generate Eocene appinite magmas, as transitional rocks, which evolved to Eocene intermediate-felsic rocks through magma-crust interaction and accumulation/fractionation after the initial melts formed in the lower crust. The timing of the CCC formation (50–40 Ma) corresponds to an amphibolite metamorphism involving temperatures of 600–800 °C, associated with partial melting during the regional back-arc extension. The formation of new crust, through the reactivation and recycl","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126290"},"PeriodicalIF":2.6,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143877471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Spectroscopic signatures for expeditious monitoring of contamination risks at abandoned coal mine sites 用于快速监测废弃煤矿污染风险的光谱特征

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Chemie Der Erde-Geochemistry

Pub Date : 2025-04-11 DOI: 10.1016/j.chemer.2025.126292

Jelena Milinovic , Patrícia Santos , Jorge Espinha Marques , Deolinda Flores , Aurora Futuro , Carlos M. Pereira , Manuel Azenha

Soil acts as a natural ‘filter’, playing a crucial role in the transfer of geogenic and anthropogenic pollutants from abandoned coal mine sites to surrounding water bodies. Key indicators of soil contamination, such as pH, electrical conductivity (EC), and organic matter (OM), expressed as loss-on-ignition (LOI), can signal contamination risks when they deviate from optimal ranges. To enable sustainable risk assessment through monitoring of pH, EC, and LOI, streamlined spectroscopic techniques Fourier transform infrared (FTIR), near-infrared (NIR), Raman, and X-ray fluorescence (XRF) were applied in combination with multivariate analysis (MVA), to soil samples from two abandoned coal mines in NW Portugal. Partial least squares (PLS) regression models demonstrated that XRF spectroscopic data provided the most accurate assessment of soil pH, EC, and LOI at the local scale (R² = 0.92–0.99). The most significant spectroscopic signatures, identified through weighted regression coefficients (B_w), enabled robust predictions of these key soil parameters. These findings highlight that these geochemical variables outperform molecular spectroscopy techniques for efficient and environmentally relevant risk monitoring of contamination in abandoned coal mine sites.

土壤是天然的 "过滤器"，在废弃煤矿场地的地质和人为污染物向周围水体转移的过程中发挥着至关重要的作用。土壤污染的关键指标，如 pH 值、导电率 (EC) 和有机质 (OM)（以点火损失率 (LOI) 表示），一旦偏离最佳范围，就会发出污染风险信号。为了通过监测 pH 值、EC 值和 LOI 值实现可持续的风险评估，对葡萄牙西北部两个废弃煤矿的土壤样本采用了傅立叶变换红外（FTIR）、近红外（NIR）、拉曼（Raman）和 X 射线荧光（XRF）等简化光谱技术，并结合多元分析（MVA）。偏最小二乘法（PLS）回归模型表明，XRF 光谱数据可在局部范围内对土壤 pH 值、EC 值和 LOI 进行最准确的评估（R2 = 0.92-0.99）。通过加权回归系数（Bw）确定的最重要光谱特征能够对这些关键土壤参数进行可靠的预测。这些研究结果表明，这些地球化学变量优于分子光谱技术，可用于对废弃煤矿场地污染进行高效且与环境相关的风险监测。

{"title":"Spectroscopic signatures for expeditious monitoring of contamination risks at abandoned coal mine sites","authors":"Jelena Milinovic , Patrícia Santos , Jorge Espinha Marques , Deolinda Flores , Aurora Futuro , Carlos M. Pereira , Manuel Azenha","doi":"10.1016/j.chemer.2025.126292","DOIUrl":"10.1016/j.chemer.2025.126292","url":null,"abstract":"<div><div>Soil acts as a natural ‘filter’, playing a crucial role in the transfer of geogenic and anthropogenic pollutants from abandoned coal mine sites to surrounding water bodies. Key indicators of soil contamination, such as pH, electrical conductivity (EC), and organic matter (OM), expressed as loss-on-ignition (LOI), can signal contamination risks when they deviate from optimal ranges. To enable sustainable risk assessment through monitoring of pH, EC, and LOI, streamlined spectroscopic techniques Fourier transform infrared (FTIR), near-infrared (NIR), Raman, and X-ray fluorescence (XRF) were applied in combination with multivariate analysis (MVA), to soil samples from two abandoned coal mines in NW Portugal. Partial least squares (PLS) regression models demonstrated that XRF spectroscopic data provided the most accurate assessment of soil pH, EC, and LOI at the local scale (R<sup>2</sup> = 0.92–0.99). The most significant spectroscopic signatures, identified through weighted regression coefficients (B<sub>w</sub>), enabled robust predictions of these key soil parameters. These findings highlight that these geochemical variables outperform molecular spectroscopy techniques for efficient and environmentally relevant risk monitoring of contamination in abandoned coal mine sites.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126292"},"PeriodicalIF":2.6,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143828522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Melting experiments of an L6 ordinary chondrite: Implications for the formation of alkali-rich achondrites L6普通球粒陨石的熔化实验：对富碱球粒陨石形成的启示

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Chemie Der Erde-Geochemistry

Pub Date : 2025-04-10 DOI: 10.1016/j.chemer.2025.126293

S. Iannini Lelarge , M. Masotta , L. Folco , T. Ubide , M.D. Suttle , L. Pittarello

We conducted high-pressure (1 GPa) melting experiments (1100–1400 °C) on the equilibrated ordinary chondrite DAV 01001 (L6) to investigate partial melting scenarios of planetary embryo in the early solar system. At 1100 °C, no melting of the silicate phase is observed, and the initial chondritic texture is preserved, but the metallic-sulphidic phases formed two immiscible Fe–Ni and S-rich liquids. Melting of silicate minerals began at 1200 °C, progressing from plagioclase to high-Ca and low-Ca pyroxene and olivine. As melting advanced, the formation of new olivine and low-Ca pyroxene resulted in the production of trachy-andesitic melt at 1200 °C, basaltic trachy-andesitic melt at 1300 °C, and andesitic melt at 1400 °C. These silicate melts have chemical similarities with some anomalous achondrites (e.g., GRA 60128/9). At the same time, minerals of new formation resemble those of primitive achondrites (e.g., brachinites, ureilites, IAB silicate inclusions, acapulcoites and lodranites). The rapid mineral-liquid re-equilibration suggests that basaltic liquids can form only above 1400 °C and that relatively high degrees of melting (>20 %) and crystallisation are necessary to explain the observed diversity of achondritic lithologies. These findings suggest that partial melting and recrystallization processes within planetary embryos could have played a critical role in the early solar system, contributing to the early differentiation of planetary bodies and the diversity of achondritic lithologies, including (but not limited to) alkali-rich achondrites.

在平衡后的普通球粒陨石DAV 01001 （L6）上进行了高压（1gpa）熔融实验（1100 ~ 1400℃），研究了早期太阳系行星胚的部分熔融情况。在1100℃时，硅酸盐相未熔化，保留了初始球粒体织构，但金属-硫化物相形成了两种不混溶的铁-镍和富s液体。硅酸盐矿物在1200℃开始熔融，从斜长石到高钙和低钙辉石和橄榄石。随着熔炼的进行，新橄榄石和低钙辉石的形成，形成了1200℃的干质-安山岩熔体、1300℃的玄武岩干质-安山岩熔体和1400℃的安山岩熔体。这些硅酸盐熔体与一些异常无球粒陨石（如GRA 60128/9）具有化学相似性。同时，新形成的矿物类似于原始无球粒岩（如：长柄岩、乌力石、IAB硅酸盐包裹体、针孔岩和菱铁矿）的矿物。快速的矿物-液体再平衡表明，玄武岩液体只能在1400°C以上形成，相对较高的熔融（> 20%）和结晶是解释观察到的球粒岩岩性多样性所必需的。这些发现表明，行星胚胎中的部分熔融和再结晶过程可能在早期太阳系中发挥了关键作用，有助于行星体的早期分化和球粒陨石岩性的多样性，包括（但不限于）富含碱的无球粒陨石。

{"title":"Melting experiments of an L6 ordinary chondrite: Implications for the formation of alkali-rich achondrites","authors":"S. Iannini Lelarge , M. Masotta , L. Folco , T. Ubide , M.D. Suttle , L. Pittarello","doi":"10.1016/j.chemer.2025.126293","DOIUrl":"10.1016/j.chemer.2025.126293","url":null,"abstract":"<div><div>We conducted high-pressure (1 GPa) melting experiments (1100–1400 °C) on the equilibrated ordinary chondrite DAV 01001 (L6) to investigate partial melting scenarios of planetary embryo in the early solar system. At 1100 °C, no melting of the silicate phase is observed, and the initial chondritic texture is preserved, but the metallic-sulphidic phases formed two immiscible Fe–Ni and S-rich liquids. Melting of silicate minerals began at 1200 °C, progressing from plagioclase to high-Ca and low-Ca pyroxene and olivine. As melting advanced, the formation of new olivine and low-Ca pyroxene resulted in the production of trachy-andesitic melt at 1200 °C, basaltic trachy-andesitic melt at 1300 °C, and andesitic melt at 1400 °C. These silicate melts have chemical similarities with some anomalous achondrites (e.g., GRA 60128/9). At the same time, minerals of new formation resemble those of primitive achondrites (e.g., brachinites, ureilites, IAB silicate inclusions, acapulcoites and lodranites). The rapid mineral-liquid re-equilibration suggests that basaltic liquids can form only above 1400 °C and that relatively high degrees of melting (>20 %) and crystallisation are necessary to explain the observed diversity of achondritic lithologies. These findings suggest that partial melting and recrystallization processes within planetary embryos could have played a critical role in the early solar system, contributing to the early differentiation of planetary bodies and the diversity of achondritic lithologies, including (but not limited to) alkali-rich achondrites.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126293"},"PeriodicalIF":2.6,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143873763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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