Lithos最新文献

{"title":"Geological and geochemical evolution of the Derhib sulfide-talc deposit in the South Eastern Desert, Egypt: Insights into ore genesis and metasomatic alteration","authors":"Mohamed Faisal ,&nbsp;Huan Li ,&nbsp;Rub'son N'nahano Heritier ,&nbsp;Muhammad A. Gul ,&nbsp;Farah A. Khedr ,&nbsp;Zhekai Zhou ,&nbsp;Sobhi M. Ghoneim","doi":"10.1016/j.lithos.2025.108049","DOIUrl":"10.1016/j.lithos.2025.108049","url":null,"abstract":"<div><div>Talc alteration is a characteristic feature of various ore deposit types, including magmatic, hydrothermal, and metamorphic systems. In the Arabian-Nubian Shield (ANS), the Derhib deposit within the Shadli Metallogenic Belt (South Eastern Desert, Egypt) represents a complex auriferous sulfide-talc system. Despite historical mining interest, the deposit remains underexplored using advanced analytical techniques, hindering our understanding of the physiochemical conditions and mechanisms governing ore precipitation. An integrated approach combining intensive field observations, petrographic investigations, and geochemical-isotopic analyses (whole rock geochemistry, U-Pb-Lu-Hf geochronology, zircon and sulfide chemistry, and S isotopes) was employed. Rhyolitic lavas in the Derhib shear zone exhibit calc-alkaline, metaluminous to peraluminous compositions, enriched in Ba, Th, Nd, U, Zr, and Sm but depleted in Nb, Ta, P, and Sr, reflecting subduction-related island-arc magmatism. Field relationships and geochemical signatures indicate a carbonate protolith for the Derhib talc deposit, evidenced by (a) the presence of chlorite adjacent to dolomite, (b) low Cr, Ni, and Co concentrations, (c) positive correlations between ΣREE and Zr, Hf, and Th, (d) similarities in REE patterns between talc ore and sedimentary samples, (e) a Y/Ho ratio in the talcose rocks aligns with carbonates rocks, (f) REE depletion inherited from carbonate units, and (g) the absence of VMS alteration zones. Magmatic zircon ages from highly sheared rhyolitic lava are largely consistent with the Shadli metavolcanics (∼695 Ma), while recrystallized zircons yield a concordia age of 137.5 ± 1.1 Ma, attributed to Upper Cretaceous volcanic episodes in the Egyptian Eastern Desert. Zircon trace elements, initial εHf(t) values (−10.5 to −17.8), and Hf crustal model ages (1.68 Ga to 2.15 Ga) indicate significant crustal involvement in their genesis. Additionally, the mineral chemistry of sulfide, chlorite, and talc, along with the sulfide δ³⁴S values (−7.57 ‰ to +3.48 ‰), reveals that the sulfides associated with highly deformed talc-rich rocks display epigenetic features, suggesting sulfur contribution from country rocks through remobilization of pre-existing sulfide ores. Structural lineaments acted as channels for mineralizing fluids, creating favorable sites for metal precipitation during ANS crustal evolution. This study provides valuable insights into the geological and geochemical processes shaping the Derhib sulfide-talc deposit. However, further geochronological and isotopic investigations are needed to fully constrain paragenetic sequence and ore genesis.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"504 ","pages":"Article 108049"},"PeriodicalIF":2.9,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143644032","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}

{"title":"Growth of a magma-filled antiform from granite emplacement to post-intrusive cooling: The Campiglia Marittima study case (Northern Apennines, Italy)","authors":"Samuele Papeschi ,&nbsp;Marco Bonini ,&nbsp;Riccardo Lanari ,&nbsp;Chiara Del Ventisette ,&nbsp;Domenico Montanari","doi":"10.1016/j.lithos.2025.108053","DOIUrl":"10.1016/j.lithos.2025.108053","url":null,"abstract":"<div><div>Regional deformation often accompanies the migration and emplacement of igneous bodies at shallow crustal levels in all tectonic regimes. Understanding the tectonic regime of magma emplacement is, however, often challenging, as plutons – especially small plutons emplaced in shallow crustal settings – may cool rapidly and not register the strain induced by coeval regional deformation. As a consequence, a wide range of models of pluton emplacement in shallow crustal settings have been proposed over the years.</div><div>Here, we describe the Botro ai Marmi Pluton from Campiglia Marittima (Tuscany, Italy), a shallow (&lt; 3–4 km) intrusive body. The pluton occurs as an elongated body in the core of an antiformal structure, at the base of Mesozoic carbonates. Structural-geological mapping coupled with a new interpretation of the available gravimetric and borehole log data show that the igneous rocks strictly follow the hinge of the antiform and the periclinal termination of the structure, and that later igneous dikes occur on the outer arc of this structure. The Botro ai Marmi antiform is oriented parallel to similar antiforms and synforms in the area, related to the regional tectonic evolution. The analysis of the distribution of deformation and contact metamorphism in the aureole shows (1) that contact metamorphism is restricted to the antiform culmination and (2) that metamorphic foliations and high-strain domains, formed during peak and retrograde metamorphism, were folded during the development of the antiform. Therefore, we propose that the intrusion and deformation of the Botro ai Marmi Pluton was controlled by the growth of a thrust anticline that continued to propagate after the emplacement and cooling of the intrusive system.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"504 ","pages":"Article 108053"},"PeriodicalIF":2.9,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143679531","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}

{"title":"Cenozoic crust-mantle interaction in response to Indian slab tearing: Insights from zircons in rhyolites in the Namco, northern of Yadong-Gulu rift","authors":"Zhe-yi Zhao ,&nbsp;Bo Xu ,&nbsp;Yi Zhao","doi":"10.1016/j.lithos.2025.108051","DOIUrl":"10.1016/j.lithos.2025.108051","url":null,"abstract":"<div><div>The crust-mantle interaction provides the driving forces and juvenile components for the surface uplift, crustal reworking, and the extensive and intense magmatism in the Tibetan Plateau. However, the spatial correlation between the Cenozoic volcanic rocks and the N-S trending rifts keeps the role of the subducted Indian slab in the upwelling of mantle materials and the crust-mantle interaction remain highly controversial. New zircon U-Pb dating, combined with trace element and Hf isotope studies, and mineral inclusion analysis of the Cenozoic Namco rhyolites, which are emplaced along the Yadong-Gulu rift (YGR), can provide additional constraints on this issue. The zircons from the Namco rhyolites exhibit high Th/U ratios (0.3 to 4.8), combined with the zircon morphology and the presence of calcite and anorthoclase inclusions, indicating a magmatic origin within a continental crust setting. These zircons exhibit two prominent age peaks (ca. 52 Ma with ca. 115 Ma) within a broad age range spanning from 49 to 3198 Ma. The younger age peak suggests the formation age of the Namco rhyolites, while the older age peak corresponds to the record of magmatic activity of the Zenong Group. The Early Cenozoic <em>syn</em>-magmatic zircons exhibit negative ε_Hf(t) (−9.8 to −1.5) and high ΔFMQ (−0.28 to 3.97) values, implying that the Namco rhyolites originated from the partial melting of the ancient lower crust in Central Lhasa. Furthermore, these zircons are also characterized by elevated zircon saturation temperatures (704° to 1107 °C) and transitional Hf isotopic composition, which suggest the involvement of upwelling asthenosphere mantle in the formation of rhyolites. The crustal thickness in the Namco area exhibits a thinning process at ca. 52 Ma. This variation can be attributed to the tearing of the subducted Indian slab. The tearing penetrated the entire Indian slab, enhancing local mantle convection, which in turn thinned the subcontinental lithospheric mantle in the Namco area and provided a vertical pathway for the upwelling asthenosphere material. Therefore, we propose that the tearing of the subducted Indian slab had a substantially more significant impact on the crust-mantle interaction beneath the Tibetan plateau and on the formation of the YGR system.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"504 ","pages":"Article 108051"},"PeriodicalIF":2.9,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143641752","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}

{"title":"Crustal evolution of Ordovician to Devonian subduction and collision zones of eastern Central Asian Orogenic Belt: Insight from igneous rocks of Xing'an Block","authors":"Yin Xu ,&nbsp;Yanhai Yang ,&nbsp;Zhiwei Wang ,&nbsp;Bei Xu ,&nbsp;Qiwei Lu ,&nbsp;Xinyu Li ,&nbsp;Aiqun Xiao ,&nbsp;Yuxin Sun ,&nbsp;Zhenyu Liu ,&nbsp;Liyang Zhang ,&nbsp;Zhenning Yang ,&nbsp;Yaqi Wang ,&nbsp;Di Wang","doi":"10.1016/j.lithos.2025.108041","DOIUrl":"10.1016/j.lithos.2025.108041","url":null,"abstract":"<div><div>Different phases of subduction and arc-continent collision commonly influence magmatic flare-ups and lulls, as well as processes of crustal accretion and reworking. Well-preserved Ordovician to Devonian magmatic and sedimentary records in the western Xing'an Block (XAB) provide valuable insights into the Paleozoic oceanic crust subduction phases and their effects on arc magmatism and crustal evolution. Zircon U-Pb dating results reveals newly identified Early Ordovician–Devonian granitoids and dacites in the western XAB, forming at 474–462, 449–446, 421–417, 383, and 367 Ma. Voluminous Ordovician to Devonian igneous rocks in western XAB documented a long magmatic life span (499–367 Ma) with a high-flux (flare-up) event occurring at 449–439 Ma and a magmatic lull from 400 to 370 Ma. Whole-rock geochemical data and zircon Hf isotopes suggest that Late Ordovician biotite monzogranite magma with high temperatures (843–852 °C) features, formed through partial melting of Mesoproterozoic accreted mafic crust with an amphibole-dominated residue. In contrast, fluid-present partial melting of pelitic rocks produced Late Silurian and Early Devonian (421–417 Ma) muscovite monzogranite and two-mica monzogranite, while Late Devonian dacite magma originated from partial melting of juvenile mafic lower crust. The Late Ordovician flare-up event, marked by voluminous high temperature granitoids, coeval bimodal volcanic rocks and Nb-rich gabbro was likely triggered by ridge subduction. A transition from advancing to retreating subduction during the Ordovician drove systematic crustal thickness changes and a shift from dominant crustal reworking and minor juvenile crust melting outboard, to mixing of dominant ancient and minor juvenile crustal materials in western XAB. Late Silurian and Early Devonian collapse extension following arc-continent collision induced extensive remelting of Proterozoic sedimentary rocks, while sustained Middle to Late Devonian extension promoted extensive partial melting of juvenile crust.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"504 ","pages":"Article 108041"},"PeriodicalIF":2.9,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143644033","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}

{"title":"Continental melting and growth through subduction processes: Evidence from the petrogenesis of Paleozoic granitoids and gabbros in the Qinling Orogen","authors":"Zhi-Wei Fan ,&nbsp;Bin Li ,&nbsp;Yong-Jun Shao ,&nbsp;Matthew J. Brzozowski ,&nbsp;John A. Mavrogenes ,&nbsp;Yi-Qu Xiong ,&nbsp;Ji-Heng Su ,&nbsp;Qing-Quan Liu","doi":"10.1016/j.lithos.2025.108054","DOIUrl":"10.1016/j.lithos.2025.108054","url":null,"abstract":"<div><div>The formation and evolution of the continental crust are critical to understanding Earth's geological history. This study investigates the genesis of continental adakitic rocks and the genetic relationships between granitic and gabbroic magmatism in the Lujiaping and Cha-an districts of the North Qinling Terrane, central China. Using integrated whole-rock elemental geochemistry and Sr<img>Nd isotopes, as well as zircon trace elemental and U-Pb-Lu-Hf isotopic geochemistry, we identify two distinct magmatic stages: Stage I (∼437 Ma) and Stage II (∼390 Ma). Stage I is characterized by the emplacement of the Lujiaping biotite monzogranite, which exhibits adakitic signatures, including high Sr/Y ratios (35.8–48.0), elevated SiO₂ (69.84–71.79 wt%), and low Y (6.10–8.50 ppm) and MgO (0.44–0.59 wt%). These features suggest partial melting of juvenile, mantle-derived lower crust during post-collisional crustal thickening and slab break-off in the Silurian. Stage II involves the emplacement of the Lujiaping gabbro and Cha-an muscovite granite. The gabbro is alkaline, with high MgO (7.31–11.90 wt%) and CaO (10.30–12.80 wt%), indicating derivation from a subduction-modified lithospheric mantle. In contrast, the peraluminous Cha-an granite shows flat rare earth element (REE) patterns, strong negative Eu anomalies, and isotopic evidence for mixing between lower crust and mantle-derived melts. Zircon geothermometry reveals high crystallization temperatures for the biotite monzogranite (∼996 °C) and gabbro (∼994 °C), compared to lower temperatures for the muscovite granite (∼729 °C). These thermal and geochemical signatures indicate that the Lujiaping biotite monzogranite crystallized first (∼437 Ma), followed by gabbroic intrusions (∼390 Ma), which triggered partial melting of the lower crust and the subsequent formation of the muscovite granite. This magmatic evolution reflects a dynamic tectonic setting. Thickening of the continental crust during the early Silurian, related to the collision between the Erlangping and North Qinling terranes, was followed by late Silurian crustal thinning and mantle upwelling. This transition facilitated the injection of mafic magmas and juvenile crust formation. By the Early Devonian, slab rollback and Paleo-Tethys subduction further promoted partial melting of the thickened crust and lithospheric mantle, driving the generation of compositionally diverse magmas. This study highlights the interplay between crustal thickening, thinning, and mantle dynamics in intracontinental orogens, providing new insights into the processes of continental crust formation and evolution.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"504 ","pages":"Article 108054"},"PeriodicalIF":2.9,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629204","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}

{"title":"Metasomatic controls on the chemical and isotopic composition of zoned clinopyroxene xenocrysts from the Mount Hope kimberlite, Gawler Craton, Australia","authors":"Z.J. Sudholz ,&nbsp;O. Alard ,&nbsp;A.L. Jaques ,&nbsp;G.M. Yaxley ,&nbsp;Y. Gréau ,&nbsp;C. Frigo","doi":"10.1016/j.lithos.2025.108039","DOIUrl":"10.1016/j.lithos.2025.108039","url":null,"abstract":"<div><div>Chemical and isotopic data are presented for mantle-derived clinopyroxene xenocrysts from the Mount Hope kimberlite (191 Ma), Gawler Craton (South Australia). The data are used in conjunction with single-grain pressure-temperature (PT) estimates to study the metasomatic controls on clinopyroxene composition. Our datasets reveal a complex mantle setting that consists of three suites of clinopyroxene. Clinopyroxenes from the deep cratonic lithospheric mantle (CLM) (&gt;150km) (herein suite C) are enriched in FeO and TiO₂ with uniform rare-earth element (REE) patterns, enriched light rare-earth elements (LREEs) and unradiogenic ⁸⁷Sr/⁸⁶Sr isotopic ratios. They have chemical and isotopic compositions that overlap with clinopyroxenes from phlogopite-ilmenite-diopside (PIC) xenolith suites and low-Cr clinopyroxene megacrysts found in kimberlites elsewhere. The chemistry of the clinopyroxenes indicates an origin involving metasomatic enrichment from asthenosphere-derived melts. Clinopyroxenes from the shallow CLM (&lt;110 km) have compositionally distinct cores (suite A) and rims (suite B). Cores have high Mg# (0.93–0.96 where Mg# = Mg/(Mg + Fe)) and Cr₂O₃ (0.55–2.0 wt%), and varied REE concentrations that includes HREE-depleted types. The samples have more radiogenic ⁸⁷Sr/⁸⁶Sr isotopic ratios in comparison to suite C. The clinopyroxenes equilibrated with garnet and orthopyroxene in an initially depleted peridotite source that had been enriched in LREEs prior to kimberlite magmatism. Clinopyroxene rims (suite B) are aegirine-rich and have rounded rim textures that contain inclusions of barite, apatite, perovskite, calcite, phlogopite, and richterite amphibole. They have similar Mg# and TiO₂ but much lower Al₂O₃ and CaO contents compared to the cores. These compositions did not equilibrate with garnet or orthopyroxene. Their trace element patterns record enrichments in LREE's and high-field strength elements (HFSE), with slight depletions for Er, Tm, Yb and Lu. Both cores and rims have similar age-corrected ⁸⁷Sr/⁸⁶Sr isotopic ratios, suggesting that they are chronologically related. We suggest that the rims formed shortly before, or during kimberlite magmatism, by melt-rock interactions with the host magma. This process may have involved dissolution and reprecipitation of portions of the suite A cores. Taken together, our results provide new insights into the metasomatic compositions of clinopyroxenes from the Gawler Craton and the important roles that low-volume melts from the asthenosphere play in the chemical and isotopic enrichment of the cratonic lithosphere, and transportation of volatiles and incompatible elements.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"504 ","pages":"Article 108039"},"PeriodicalIF":2.9,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143619280","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}

{"title":"Duality of Paleo- and Neoarchean metamorphism as recorded in disparate Eoarchean (pre-3700 Ma) sedimentary protoliths","authors":"P. Tropper ,&nbsp;J. Peine ,&nbsp;A.K. Schmitt ,&nbsp;S.J. Mojzsis ,&nbsp;C.E. Manning","doi":"10.1016/j.lithos.2025.108037","DOIUrl":"10.1016/j.lithos.2025.108037","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The oldest supracrustal belts are our best archives of early surficial processes; two well-known ancient examples occur in southern West Greenland (Færinghavn terrane) and northern Québec (Inukjuak domain). Despite their widespread interest, the metamorphic histories of these rocks are little constrained. Previous work on the Akilia (sample GR114 from Manning et al., 2006) and Innersuartuut islands (sample GR27b from Cates and Mojzsis, 2006), Færinghavn supracrustal enclaves reported minor anthophyllite-garnet rocks with rare metamorphic zircons yielding common U&lt;img&gt;Pb core ages of ca. 3650 Ma and rim ages at ca. 2700 Ma. The main mineral assemblages comprise garnet + anthophyllite + hornblende + biotite + plagioclase + K-feldspar + quartz. Secondary biotite and plagioclase with diffusive modification of the garnet compositions along fractures points to a later metamorphic overprint. Our new phase equilibrium calculations of the main matrix assemblage yield average &lt;em&gt;P-T&lt;/em&gt; conditions (± 1σ) of 580 ± 40 °C and 0.6 ± 0.1 GPa for both Akilia and Innersuartuut. Zr-in-rutile geothermometry of rutile inclusions in garnet from an Akilia sample (GR114) shows increasing &lt;em&gt;T&lt;/em&gt; from 610 ± 30 °C (core) to 670 ± 30 °C (rim). Rutile U&lt;img&gt;Pb geochronology yields discordant ages (± 1σ) ranging from 2410 ± 56 Ma to 1383 ± 78 Ma: the upper intercept age of 2542 ± 214 Ma overlaps with uncertainties previously reported U&lt;img&gt;Pb zircon rim ages around 2700 Ma and a lower intercept at 1014 ± 237 Ma points to a Grenville/Sveconorwegian orogen overprint. An Inukjuak domain coarse-grained quartzite (sample IN14032 from Greer et al., 2022) contains several different zircon age populations; the oldest (detrital) zircons have a weighted average &lt;sup&gt;207&lt;/sup&gt;Pb/&lt;sup&gt;206&lt;/sup&gt;Pb age of 3736 ± 5 Ma. Two younger, smaller, zircon populations cluster around 3650 Ma and ca. 2700 Ma. The main mineral assemblage is anthophyllite + muscovite + quartz + rutile. Former biotite is replaced by stilpnomelane, and anthophyllite is replaced by chlorite + talc. Pervasive greenschist-facies retrogression of the sample prevents the calculation of &lt;em&gt;P-T&lt;/em&gt; conditions using phase equilibrium calculations. Zr-in-rutile geothermometry limits &lt;em&gt;T&lt;/em&gt; at an assumed pressure (0.6 GPa) to 670 °C ± 20 °C (± 1σ). Rutile U&lt;img&gt;Pb geochronology yielded 2538 ± 10 Ma, an age which correlates well with the youngest zircon age cluster, consistent with the lower closure &lt;em&gt;T&lt;/em&gt; for Zr diffusion in rutile (&lt;600 °C).&lt;/div&gt;&lt;div&gt;The Færinghavn and Inukjuak supracrustal rocks experienced synchronic Neoarchean metamorphism at analagous upper amphibolite-facies conditions (580–670 °C). Our &lt;em&gt;P-T&lt;/em&gt; data agree very well with intermediate thermal &lt;em&gt;dT/dP&lt;/em&gt; gradient from the literature that are typical for the Neoarchean geodynamic setting of paired metamorphic belts. Evidence of for a high-greenschist-lower amphibolite-facies overprint during the Late Proterozoic Grenville/S","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"504 ","pages":"Article 108037"},"PeriodicalIF":2.9,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592838","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}

{"title":"Petrogenesis and evolution of Miocene-Quaternary continental basalts at Harrat Ash Shaam (Al Harrah), NW Saudi Arabia","authors":"Shelby Bowden ,&nbsp;Tanya Furman ,&nbsp;David W. Graham ,&nbsp;Mansour Alhumimidi ,&nbsp;Willis Hames ,&nbsp;Ali Assiri ,&nbsp;Mazen Alyousif ,&nbsp;Ramzi Almutairi ,&nbsp;Hamad Alqahtani ,&nbsp;Abdurahman Bin Rogaib ,&nbsp;Abdulaziz Bin Rushood ,&nbsp;Khaled AlYousef ,&nbsp;Sultan Alkhammali","doi":"10.1016/j.lithos.2025.108031","DOIUrl":"10.1016/j.lithos.2025.108031","url":null,"abstract":"<div><div>The geochemical compositions of Miocene-recent basalts from Harrat Ash Shaam (HAS) contain a record of the temporal and spatial evolution of the subcontinental lithospheric mantle in response to regional tectonics in northern Saudi Arabia. HAS lavas show two distinct episodes of magmatism: (1) widespread Oligocene/early-Miocene through mid-Miocene effusive, plateau-forming subalkaline basalts and (2) Late-Miocene through historic primitive alkaline basalts erupted from monogenetic cinder cones superimposed on the existing volcanic plateau. Geochemical evidence indicates a change in the source region mineralogy from spinel peridotite/pyroxenite with minor amounts of hydrous phases (amphibole/phlogopite) in the early Miocene to garnet peridotite/pyroxenite with abundant amphibole and phlogopite in the Quaternary. Melt equilibration pressures and temperatures in Quaternary (1 to <span><math><mo>&gt;</mo></math></span>5 GPa, <span><math><mo>≈</mo></math></span>1300–1500 <span><math><msup><mrow></mrow><mo>∘</mo></msup></math></span>C) and Miocene/Pliocene (<span><math><mo>&lt;</mo></math></span>1 to 3 GPa, <span><math><mo>≈</mo></math></span>1250–1400 <span><math><msup><mrow></mrow><mo>∘</mo></msup></math></span>C) lavas, plus REE evidence (e.g., Tb/Yb_<em>n</em> = 3.7 in the Quaternary vs. 2.6 in the Miocene), suggest a deepening of the melt region through time. Olivine ³He/⁴He ratios range from 6 to 9 R_<em>A</em> and do not require contributions from a deep-seated mantle plume; we suggest that genesis of the older Miocene basalts involved contributions of melt from the asthenosphere. Petrogenesis of Cenozoic HAS lavas occurred in two stages. Oligocene through mid-Miocene magmas formed from adiabatic melting of lithospheric and sub-lithospheric mantle associated with movement along the Azraq-Sirhan Graben during widespread extension across the Arabian Peninsula. Late-Miocene through present day magmatism was likely triggered by foundering of unstable (dense, metasomatized) lithosphere into the underlying asthenosphere, triggering lithospheric and asthenospheric melting subsequent to and coeval with tectonic movement along the Dead Sea Fault.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"504 ","pages":"Article 108031"},"PeriodicalIF":2.9,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601613","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}

{"title":"Possible lateral flow in the Big Mantle Wedge of Northeast China revealed by the geochemistry of Cenozoic basalts","authors":"Zhong-Biao Zhou ,&nbsp;Li-Hui Chen ,&nbsp;Xiao-Jun Wang ,&nbsp;Jian-Qiang Liu ,&nbsp;Gang Zeng ,&nbsp;Zhou-Chuan Huang","doi":"10.1016/j.lithos.2025.108036","DOIUrl":"10.1016/j.lithos.2025.108036","url":null,"abstract":"<div><div>In eastern Asia, the subducting Pacific slab is stagnant in the mantle transition zone (MTZ), and the upper mantle above the slab is termed the Big Mantle Wedge (BMW). However, how the BMW runs and controls the distribution of the above volcanism remains poorly understood. To test possible convective patterns of the BMW, we compare the geochemical compositions of Cenozoic basalts from different localities in eastern Northeast China. These basalts exhibit broad ⁸⁷Sr/⁸⁶Sr (0.7037–0.7054) and ¹⁴³Nd/¹⁴⁴Nd (0.51250–0.51288) ratios and compose binary mixing trends on the plots of ⁸⁷Sr/⁸⁶Sr versus ¹⁴³Nd/¹⁴⁴Nd and selected elemental ratios (e.g., Rb/Nb, Nb/Th and MgO/SiO₂). Statistically, the compositions of basalts strongly correlate with their spatial distributions. The closer to the Songliao basin with thinner lithosphere, the more depleted; the closer to the Changbaishan Volcano with thicker lithosphere, the more enriched. Furthermore, we simulate the decompressional melting process of a lithologically heterogeneous mantle, by using a previously-established software REEBOX PRO (Brown and Lesher, 2016). The results demonstrate that melting of the vertical-upwelling mantle within a limited depth range beneath eastern Northeast China cannot adequately account for the observed broad chemical variations unless the deep-sourced enriched melts have been partially removed prior to the upwelling mantle reaching a thinner lithosphere. Therefore, we conclude that vertical mantle upwelling beneath Changbaishan Volcano might change into lateral flows at the lithosphere-asthenosphere boundary, which could be responsible for the scattered Cenozoic volcanism. This attempt links geochemical variations in continental basalts to geodynamics of the BMW and provides an example to verify possible mantle convective patterns quantitatively for other areas in eastern Asia.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"504 ","pages":"Article 108036"},"PeriodicalIF":2.9,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592835","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}

{"title":"Formation of Mg-rich kuliginite (Fe3Mg(OH)6Cl2) during serpentinization by saline fluids","authors":"Long Zhang ,&nbsp;Qiang Wang ,&nbsp;Denis S. Mikhailenko ,&nbsp;Haiyang Xian ,&nbsp;Xing Ding ,&nbsp;Wan-Cai Li ,&nbsp;Yiping Yang","doi":"10.1016/j.lithos.2025.108040","DOIUrl":"10.1016/j.lithos.2025.108040","url":null,"abstract":"<div><div>Serpentinization generally occurs in the presence of Cl-bearing fluids, but formation of chloride minerals and their role in serpentinization are poorly understood. Kuliginite, a hydroxychloride mineral with the ideal formula of Fe₃Mg(OH)₆Cl₂, was recently identified in serpentinized rocks from New Caledonia, and it was suggested that kuliginite may significantly influence iron distribution and hydrogen generation during serpentinization by Cl-rich fluids. In this study, we re-investigate kuliginite from New Caledonia, and reveal that the kuliginite is mostly Mg-rich and Fe-depleted compared with holotype kuliginite, in contrast to previous conclusion that the kuliginite closely resembles holotype kuliginite. Overall, Mg-rich kuliginite formed preferentially over holotype-like kuliginite in serpentinized rocks from New Caledonia, which may be ascribed to higher stability of the former than the latter. Despite some substitution of Fe by Mg, Mg-rich kuliginite still contains large amounts of iron (∼ 50 wt% FeO). Therefore, Mg-rich kuliginite can also greatly impact iron partitioning and hydrogen generation once it forms during serpentinization by Cl-rich saline fluids.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"504 ","pages":"Article 108040"},"PeriodicalIF":2.9,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592836","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}