Chemical Geology最新文献

{"title":"Scandium mineralization during ultramafic-mafic magmatism in the subduction zone","authors":"Xin Chen , Hans-Peter Schertl , Junaid Khan , Pengjie Cai , Dongyang Lian , Jinshou Wang , Chengtao Yu , Hao Lin , Xiaojia Jiang","doi":"10.1016/j.chemgeo.2024.122556","DOIUrl":"10.1016/j.chemgeo.2024.122556","url":null,"abstract":"<div><div>Sandium (Sc) has gained strategic importance due to its diverse applications. Magmatic ultramafic-hosted deposits are emerging as significant Sc reservoirs, not only for their direct reserves but also as precursors for laterite-hosted Sc deposits. However, the processes controlling Sc enrichment in magmatic systems remain poorly understood. This study reveals the discovery of a potentially significant Sc mineralization within an ultramafic complex of the Shangzhuang P–REE deposit, situated in the Lajishan region of western China. The ultramafic complex comprises fluorapatite-rich biotite clinopyroxenite and calcite-amphibole-K-feldspar-rich clinopyroxenite hosted in biotite clinopyroxenite. Whole-rock concentrations of Sc range from 35.9 to 134 ppm in these three rocks mentioned, while clinopyroxenes in the complex exhibit Sc concentrations ranging from 56 to 203 ppm. Zircon U<img>Pb dating on three ultramafic clinopyroxenites yield consistent crystallization ages of 465 ± 2 Ma, indicating an Ordovician magmatic and Sc mineralization event coinciding with the subduction stage of the Proto-Tethys Ocean beneath the central Qilian block. Field observations, consistent ages, narrow range of Hf and Sr isotope data (zircon ε<sub>Hf</sub>(t): +3.2 − +13.5; clinopyroxene <sup>87</sup>Sr/<sup>86</sup>Sr: 0.704534–0.705715), and decreasing Mg<sup>#</sup> trend observed in both clinopyroxene-bearing whole-rock and clinopyroxene single-grain samples from the three ultramafic rocks suggest a common magmatic origin with varying degrees of fractional crystallization and crystal accumulation within an evolved magmatic system. The parent magma likely originated from a potassium-Sc-REE-rich basaltic composition. This magma was primarily sourced from carbonated phlogopite-garnet lherzolite lithospheric mantle, but had been modified by carbonate-rich fluids derived from subducted oceanic sediments during the subduction of the Proto-Tethys Ocean. The comprehension of multistage growth processes in clinopyroxene effectively signifies the extent of magmatic differentiation and points to the involvement of magma sources in the formation of Sc deposits. Significant fluctuations of Sc concentration within clinopyroxene can be attributed to variable magma compositions. Enrichment of phosphate and fluorine effectively promotes Sc migration during magma evolution, while partition coefficient of Sc into clinopyroxene may be significantly higher in a P-F-rich magma, which causes Sc to concentrate in the apatite-rich biotite clinopyroxenite. The relatively high amount of Sc in the parent magma may be related to its initial enrichment in the carbonated fertile mantle. These compositions likely result from different amounts of phosphate and fluorine in the subduction-related fluid percolating through ultramafic mantle rocks. This study significantly advances our understanding of intricate processes involved in developing Sc mineralization in an ultramafic system, consid","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"673 ","pages":"Article 122556"},"PeriodicalIF":3.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142887307","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":"Linking the oxygen-17 compositions of water and carbonate reference materials using infrared absorption spectroscopy of carbon dioxide","authors":"Justin Chaillot ,&nbsp;Samir Kassi ,&nbsp;Thibault Clauzel ,&nbsp;Marie Pesnin ,&nbsp;Mathieu Casado ,&nbsp;Amaëlle Landais ,&nbsp;Mathieu Daëron","doi":"10.1016/j.chemgeo.2024.122450","DOIUrl":"10.1016/j.chemgeo.2024.122450","url":null,"abstract":"<div><div>Joint measurements of the ¹⁸O/¹⁶O and ¹⁷O/¹⁶O ratios of carbonate minerals and waters are increasingly used to investigate various geochemical, physical and biological processes. Diverse analytical methods, each of them technically challenging in one way or another, have been developed or refined in recent years to measure oxygen-17 anomalies (Δ’¹⁷O) with instrumental precisions of 10 ppm or better. A critical underpinning of all these methods is how the international carbonate reference materials currently anchoring the VPDB ¹⁸O/¹⁶O scale are linked to the primary VSMOW-SLAP scale in (¹⁸O/¹⁶O, ¹⁷O/¹⁶O) space. For now, however, substantial systematic discrepancies persist between different groups and methods, even after all measurements are nominally standardized to VSMOW-SLAP.</div><div>Here we take advantage of VCOF-CRDS, a novel spectroscopic method combining the ease and simplicity of near-infra-red absorption measurements in pure CO₂ with metrological performance competitive with state-of-the-art IRMS techniques, to precisely characterize, based on previously reported equilibrium fractionation factors between water and CO₂, the relative triple oxygen isotope compositions of international water standards (VSMOW2, SLAP2, GRESP) and CO₂ produced by phosphoric acid reaction of carbonate standards (NBS18, NBS19, IAEA603, IAEA610, IAEA611, IAEA612). The robustness of our results derives from the demonstrated linearity of our measurements (RMSE ≈ 1 ppm), but also from the fact that, when equilibrated with or converted to CO₂, all of these reference materials yield analytes with closely comparable oxygen-18 compositions. In light of these observations, we revisit potential causes of the large inter-laboratory discrepancies reported so far. Collectively reconciling the different types of measurements constraining the relative ¹⁷O/¹⁶O ratios of the two standards most often used to normalize carbonate analyses (NBS18, IAEA603) is a matter of high priority.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"673 ","pages":"Article 122450"},"PeriodicalIF":3.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142815784","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":"Unraveling the link between worldwide adakite-like rocks and porphyry Cu deposits","authors":"Chao Wu ,&nbsp;Guoxiong Chen ,&nbsp;Huayong Chen","doi":"10.1016/j.chemgeo.2024.122521","DOIUrl":"10.1016/j.chemgeo.2024.122521","url":null,"abstract":"<div><div>Adakite-like rocks, as an important recorder of magmatic evolution in mantle and crust, are closely associated with major porphyry Cu deposits. However, the underlying mechanism connecting these associations remains insufficiently elucidated. This study compiles ca. 7000 whole-rock geochemical data from Phanerozoic adakite-like rock samples and from ore-forming porphyries in porphyry Cu deposits. Machine learning investigations are performed to characterize the geochemical variations of adakite-like rocks from various orogenic or cratonic systems and investigate any geochemical similarities with rocks associated with porphyry ore systems. Principal component analysis (PCA), along with t-distributed Stochastic Neighbor Embedding (t-SNE), highlights elemental distinctions between adakite-like rocks formed in mature and juvenile crust and the similarities of rocks from porphyry Cu<img>Mo deposits with the former and rocks from porphyry Cu<img>Au deposits with the latter. Extreme Gradient Boosting (XGBoost) and Support Vector Machine (SVM) analyses are applied to the original dataset and the PCA data derived from the dataset to discriminate adakite-like rocks from various geodynamic settings from each other and from rocks associated with porphyry ore deposits. Our models show that XGBoost and SVM can identify the tectonic regions of adakite-like rocks and rocks from porphyry copper systems with high efficiency and confidence e.g., accuracy = 0.88–0.94 and area under curve (AUC) = 0.69–0.86. The application of SHapley Additive exPlanations (SHAP) values is employed to elucidate the parameters that discriminate the different environments, providing insight into the underlying petrogenetic processes, including diverse levels of formation depth and extent of mantle interaction. Additionally, when examining ore-forming porphyries and adakite-like rocks, the incorporation of heatmaps into taxonomic classification (HTC) provides significant distinguishing factors with substantial geological implications. These findings suggest potential geological processes (e.g., remelting of Cu-sulfide-bearing cumulates or flotation of Cu-sulfide phases attached to vapor bubbles) that may enrich the source magma of ore-forming porphyries beyond the conventional geological processes responsible for adakite-like rock formation, which could serve as an exploration indicator.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"673 ","pages":"Article 122521"},"PeriodicalIF":3.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142815835","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":"Multistage formation and geochemical response of pipe-morphology cold seep carbonate in the Qiongdongnan Basin, northern South China Sea","authors":"Jing Zhao ,&nbsp;Xuewan Wu ,&nbsp;Wei Zhang ,&nbsp;Zhifeng Wan ,&nbsp;Yifei Dong ,&nbsp;Xi Xiao ,&nbsp;Yang Wu ,&nbsp;Xiaoyu Wu ,&nbsp;Junxi Feng ,&nbsp;Qianyong Liang","doi":"10.1016/j.chemgeo.2024.122524","DOIUrl":"10.1016/j.chemgeo.2024.122524","url":null,"abstract":"<div><div>Cold seep carbonates are commonly used to record the nature of seepage, including fluid sources, diagenetic environments, and variations in seepage activity. However, the relationship between diagenetic environments and trace element enrichment in dynamic environments is poorly understood. Pipe-morphology cold seep carbonates form from outside to inside in methane seeps and record variations in elements and isotopes over time, which can be used to reconstruct diagenetic environments and fluid dynamics. In this work, we analysed the mineral compositions, carbon and oxygen (C<img>O) isotopes and major and trace element contents in different areas of pipe-morphology cold seep carbonate collected from the Qiongdongnan Basin in different growth directions. The cold seep carbonate exhibits changes from high-magnesian calcite (HMC) to aragonite and then to HMC, indicating that it has undergone changes in the sedimentary environment inside the fluid migration pathway. On the basis of these findings, the formation of this pipe-morphology cold seep carbonate is divided into three stages. The low δ¹³C values (from −36.13 ‰ to −32.18 ‰) indicate anaerobic oxidation of methane during carbonate formation. The response of δ¹³C to changes in the methane flux is not obvious. The gradual increase in δ¹⁸O from the outer to the inner portions suggests that the methane flux affected δ¹⁸O. The samples have relatively high enrichment factors (EFs) of molybdenum (Mo) and high molybdenum/uranium (Mo/U) ratios. The U_EF values show an increasing trend from the outer to the inner portions, whereas the changes in Mo_EF, Cd_EF and V_EF are not obvious. However, Mo_EF, Cd_EF, and V_EF all have good correlations with Mn/Al and Fe/Al, indicating that the particulate shuttle process significantly impacts the enrichment of Mo, Cd, and V. We concluded that the enrichment of U is influenced by the methane flux, whereas the enrichment of Mo, Cd and V is unrelated to methane dynamics. This study provides insights into the behaviour of the methane flux and seawater, redox-sensitive trace element contents and changes in the sedimentary environment and plays an essential role in understanding the activities of cold seeps in dynamic environments.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"673 ","pages":"Article 122524"},"PeriodicalIF":3.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142815919","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":"Single quartz δ18O: A new frontier in detrital provenance analysis (Bengal Fan, IODP Expedition 354)","authors":"Mara Limonta ,&nbsp;Christian France-Lanord ,&nbsp;Albert Galy ,&nbsp;Andrey Gurenko ,&nbsp;Nordine Bouden ,&nbsp;Eduardo Garzanti","doi":"10.1016/j.chemgeo.2024.122525","DOIUrl":"10.1016/j.chemgeo.2024.122525","url":null,"abstract":"<div><div>Quartz is the most abundant mineral in sediments and sedimentary rocks but efforts to reliably identify its provenance have been only partially fruitful so far. Even advanced methods such as cathodo-luminescence, Raman spectroscopy, synchrotron X-ray absorption spectroscopy, and laser ablation spectrometry have led to limited success. This article demonstrates how the δ¹⁸O of detrital quartz provides useful additional insight. The oxygen-isotope signature primarily depends on source rocks and their formation conditions, being highly different for different crustal sources and highest for carbonate rocks.</div><div>This study illustrates a new protocol to analyze δ¹⁸O signatures of single quartz grains and shows how provenance from magmatic, metamorphic, or sedimentary domains can be discriminated. In each sand sample from rivers draining exclusively a single Himalayan tectonic domain (e.g., Trans-Himalaya, Greater Himalaya, Lesser Himalaya, and Tethys Himalaya), ∼200 quartz grains were analyzed by ion microprobe LG-SIMS (Large Geometry Secondary Ion Mass Spectrometry) to characterize their oxygen-isotope variability. In each turbidite sample collected from the Bengal Fan during IODP Expedition 354, ∼150 quartz grains were analyzed next to quantify the relative contribution of each Himalayan domain. This allowed us to complement data obtained with other bulk-sediment to single-mineral approaches, thus enhancing provenance resolution and highlight the erosional evolution of the Himalayan-Tibetan orogen through time.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"673 ","pages":"Article 122525"},"PeriodicalIF":3.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142858013","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":"Re-Os isotopic evidence for ancient melt depletion in refertilized Neo-Tethyan suboceanic mantle domain","authors":"Yang Xu ,&nbsp;Chuan-Zhou Liu ,&nbsp;Chang Zhang ,&nbsp;Tong Liu","doi":"10.1016/j.chemgeo.2024.122520","DOIUrl":"10.1016/j.chemgeo.2024.122520","url":null,"abstract":"<div><div>Ancient mantle domains with unradiogenic Os isotopes have been well documented in the Yarlung-Tsangpo ophiolites (YTO), southern Tibet. Nonetheless, previous Os isotope studies have yielded relatively young <em>Re</em>-depletion model (T_RD) ages of &lt;1.0 Ga for mantle peridotites of the Zedong ophiolite in the eastern segment of the YTO. In this study, a comprehensive petrological and geochemical study has been conducted on a suite of mantle samples including harzburgites, lherzolites and one pyroxenite. Our results indicate that the Zedong harzburgites have been subjected to low to moderate degrees (∼6–20 %) of partial melting and late-stage melt-rock interaction with basaltic melts. In contrast, both lherzolites and pyroxenite were generated by melt refertilization. The Zedong lherzolites display flat patterns of highly siderophile elements (HSE; Os, Ir, Ru, Pt, Pd, Re), whereas the harzburgites show depletion in Pt, Pd and Re relative to Os, Ir and Ru. The <em>Re</em>-Os isotopes of the Zedong lherzolites have been modified by melt refertilization and thus cannot provide reliable age information. Three Zedong harzburgites with the lowest Pd_N/Ir_N and Re_N/Ir_N ratios have the least radiogenic ¹⁸⁷Os/¹⁸⁸Os of 0.11497–0.11537, giving the old T_RD ages of 1.89–1.98 Ga. These ages are considerably older than previously reported T_RD ages for the Zedong peridotites (&lt; 1.0 Ga), but comparable to the oldest T_RD age for the Luobusa peridotites. This supports the occurrence of similarly old mantle domains in both Zedong and Luobusa ophiolites in the eastern part of the YTO. The Zedong pyroxenite has a radiogenic ¹⁸⁷Os/¹⁸⁸Os ratio of 0.158 that is similar to the ¹⁸⁷Os/¹⁸⁸Os ratios (0.156–0.180) of previously reported for the YTO pyroxenites, which can be explained by selective assimilation of interstitial sulfides during the percolation of migrating melts through the mantle lithosphere. Grain boundary sulfides may play a significant role in the high ¹⁸⁷Os/¹⁸⁸Os of the YTO pyroxenites.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"673 ","pages":"Article 122520"},"PeriodicalIF":3.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142777462","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":"Extreme rare earth element (REE) enrichment during weathering recorded in saprolites from South Carolina","authors":"Utpalendu Haldar ,&nbsp;Ramananda Chakrabarti ,&nbsp;Roberta L. Rudnick","doi":"10.1016/j.chemgeo.2024.122553","DOIUrl":"10.1016/j.chemgeo.2024.122553","url":null,"abstract":"<div><div>Rare earth elements (REE) and other trace element concentrations as well as ¹⁴³Nd/¹⁴⁴Nd and ⁸⁷Sr/⁸⁶Sr in saprolites developed on the Cayce metadiabase dike, South Carolina, document extreme REE mobilization during chemical weathering and enrichment of REE on clays. Saprolites display a bimodal distribution in their total REE concentrations (ΣREE) and light-REE (LREE)/heavy-REE (HREE) ratios. Shallower (0–6 m depth), Group I, saprolites have high ΣREE (up to 2633 ppm) with enrichment of LREE &gt; MREE &gt; HREE. Group II saprolites, at &gt;6 m depth, have lower ΣREE (45–67 ppm) and relatively flat LREE/HREE, similar to the unweathered metadiabase. Group I saprolites are more weathered (chemical index of alteration (CIA) values of 87–95), than the Group II saprolites (CIA = 46–88, with most &lt;55). Mass balance calculations using ¹⁴³Nd/¹⁴⁴Nd rules out significant input of dust to the weathering profile, which is consistent with the lack of depth-dependent variation in ε_Nd. Weathering and REE enrichment occurred through a three-stage process. Stage 1 involved regional weathering during which saprolites developed on both the metadiabase dike and Liberty Hill granite country rock. During this stage, breakdown of LREE-rich accessory minerals (e.g., titanite) in the granite released REE and radiogenic Sr to weathering fluids that penetrated the metadiabase where these elements were adsorbed onto clays, consistent with their Nd and Sr isotopic compositions. The kaolinite/smectite (K/S) ratio in Group II saprolites negatively correlates with Sm/Nd and positively with Y/Ho and Rb/Sr ratios indicating preferential adsorption of lighter REE (e.g., Nd), Y, and Rb by kaolinites; no trends are seen in Group I saprolites, suggesting that these samples were overprinted by later events that did not impact the Group II saprolites. Stage 2 involved replacement of smectite veins by siderite in the entire saprolite at high pH and under reducing conditions such as found in swamps, which did not affect the adsorbed REE in the clays. In stage 3, siderite dissolution under acidic and oxidized conditions at the shallowest depths (upper 2 m) led to the formation of Fe³⁺-smectite and LREE mobilization; this REE-bearing fluid percolated downwards where the REE were adsorbed onto clays to develop a REE-enriched zone locally in the upper 6 m (within the Group I saprolites). Carbonates may have also acted as depositional ligands and induced REE precipitation. This study shows that REE can be extremely mobile during chemical weathering under specific conditions and may be deposited onto secondary clay minerals like kaolinites, which absorb REE, particularly LREE, leading to local enrichments.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"673 ","pages":"Article 122553"},"PeriodicalIF":3.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142815831","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":"Ca-Sr-Nd isotopic signatures of mid-ocean ridge basalts from the Central Indian Ridge and implications for recycled materials in the Indian Ocean mantle domain","authors":"Hongli Zhu ,&nbsp;Yujie Shan ,&nbsp;Renqiang Liao ,&nbsp;Lipeng Zhang ,&nbsp;Jianghong Deng ,&nbsp;Congying Li ,&nbsp;Long Du ,&nbsp;Zhaofeng Zhang ,&nbsp;Weidong Sun","doi":"10.1016/j.chemgeo.2024.122546","DOIUrl":"10.1016/j.chemgeo.2024.122546","url":null,"abstract":"<div><div>Mid-ocean ridge basalts (MORBs) from the Indian Ocean have been demonstrated to have more enriched radiogenic isotopic compositions than MORBs from the Pacific and Atlantic Oceans. However, the origin of such anomaly is still under debate. To better constrain the genesis of the isotopic anomaly observed in Indian MORBs, we present a systematic Ca-Sr-Nd isotopic study of a suite of MORBs from the Central Indian Ridge (CIR) between 19 and 20°S and the adjacent Gasitao Ridge. The δ^44/40Ca values of these MORBs vary from 0.70 to 0.89 ‰, most of which are similar to those of reported Pacific and Atlantic MORBs. However, some samples from the northern part of the studied CIR region showed slightly lower δ^44/40Ca values than the average of the reported Pacific and Atlantic MORBs. Notably, these δ^44/40Ca values are correlated with Sr<img>Nd isotopic ratios, which extend from the depleted MORB mantle to a component with lower δ^44/40Ca and more enriched Sr<img>Nd isotopic compositions, suggesting the presence of an enriched component in the source of these Indian MORBs. Recent studies have proposed that lower continental crust has similar δ^44/40Ca values to the estimated Bulk Silicate Earth, indicating that the low δ^44/40Ca signatures of some Indian MORBs are unlikely to be produced by delaminated lower continental crust. Garnet in the residue and recycled carbonate-rich marine sediments with oceanic crust can cause lower δ^44/40Ca signatures in mantle-derived rocks. However, trace element ratios and our model calculations suggest that these two factors can hardly induce the correlated Ca-Sr-Nd trends in these Indian MORBs. Instead, recently reported subcontinental lithospheric mantle xenoliths that experienced silicate and/or carbonatite metasomatism, which also show low δ^44/40Ca and enriched Sr<img>Nd isotopic compositions, correspond with the correlated Ca-Sr-Nd trends in the studied Indian MORBs. Moreover, ancient metasomatized subcontinental lithospheric mantle materials have been observed in abyssal peridotites from the Southwest Indian Ridge. Therefore, delaminated subcontinental lithospheric mantle maybe the most likely cause of the Ca-Sr-Nd isotopic anomaly in Indian MORBs. Our study suggests that combined Ca-Sr-Nd isotopes can be treated as potential tracers to the genesis of mantle heterogeneity.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"673 ","pages":"Article 122546"},"PeriodicalIF":3.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142815875","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":"A comprehensive and consistent mineral dissolution rate database: Part III: Non-silicate minerals including carbonate, sulfate, phosphate, halide, and oxy-hydroxide minerals","authors":"Eric H. Oelkers ,&nbsp;Mouadh Addassi","doi":"10.1016/j.chemgeo.2024.122528","DOIUrl":"10.1016/j.chemgeo.2024.122528","url":null,"abstract":"<div><div>This paper describes the creation of a consistent database of the far-from-equilibrium dissolution rates in aqueous fluids of the major non-silicate minerals including carbonates, sulfates, phosphates, oxides and hydroxides. This work, based on the regression of available dissolution rate data normalized to their BET surface area as a function of pH and temperature, was performed using equations described in Heřmanská et al. (2022, 2023). For carbonate minerals, an additional term was added to account for the slowing of rates in response to increasing aqueous bicarbonate and carbonate concentration. All rate equations have been incorporated into a computer accessible database allowing for the direct application of these rates to assess the temporal evolution of chemical mass transfer in laboratory and field-based systems. It is anticipated that such applications will lead to further advances in our understanding the reaction rates of individual minerals and of natural water-rock interaction in the future.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"673 ","pages":"Article 122528"},"PeriodicalIF":3.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142858011","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":"Investigating pressure effects of Ti and Zr partitioning into zircon, quartz, and rutile at crustal temperatures","authors":"Heather M. Kirkpatrick ,&nbsp;Dustin Trail ,&nbsp;T. Mark Harrison ,&nbsp;Elizabeth A. Bell","doi":"10.1016/j.chemgeo.2024.122518","DOIUrl":"10.1016/j.chemgeo.2024.122518","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The dependency of Ti partitioning between quartz and zircon on the activity of TiO&lt;sub&gt;2&lt;/sub&gt; and Zr partitioning between zircon and rutile on the activity of ZrO&lt;sub&gt;2&lt;/sub&gt; suggest that an intercalibration among the three minerals (i.e., concentration information from all three phases in the same experiment) could reduce propagated errors when using multiple systems simultaneously. Experiments were undertaken to assess pressure effects in Ti and Zr partitioning in the zircon-quartz-rutile system and intercalibration of the three phases at low concentrations (down to ∼20 ppm). Analysis of small crystals (down to ∼8 μm) was possible due to the high spatial resolution of the CAMECA &lt;em&gt;ims&lt;/em&gt;1290 ion microprobe. Regressions for pressure-temperature-phase domains for experiments between 800 and 1000 °C and 10 and 15 kbar array about the initial calibration data providing confidence in their merit despite recent criticisms. Ti and Zr partitioning into quartz, rutile, and zircon can be quantified as:&lt;span&gt;&lt;span&gt;&lt;span&gt;&lt;math&gt;&lt;mo&gt;log&lt;/mo&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mi&gt;Ti&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;in&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;quartz&lt;/mi&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mo&gt;log&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;msubsup&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mrow&gt;&lt;mi&gt;Si&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;quartz&lt;/mi&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;6.71&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;0.11&lt;/mn&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mn&gt;383&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mfenced&gt;&lt;mi&gt;K&lt;/mi&gt;&lt;/mfenced&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;0.122&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;0.07&lt;/mn&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;mi&gt;P&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;0.00197&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;0.00024&lt;/mn&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;msup&gt;&lt;mi&gt;P&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;&lt;span&gt;&lt;math&gt;&lt;mo&gt;log&lt;/mo&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mi&gt;Zr&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;in&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;rutile&lt;/mi&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mo&gt;log&lt;/mo&gt;&lt;msubsup&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mrow&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;iO&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;quartz&lt;/mi&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;7.39&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;0.21&lt;/mn&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mn&gt;4262&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;220&lt;/mn&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mfenced&gt;&lt;mi&gt;K&lt;/mi&gt;&lt;/mfenced&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;0.021&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;0.0051&lt;/mn&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;mi&gt;P&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/div&gt;&lt;div&gt;and&lt;span&gt;&lt;span&gt;&lt;span&gt;&lt;math&gt;&lt;mo&gt;log&lt;/mo&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mi&gt;Ti&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;in&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;zircon&lt;/mi&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;log&lt;/mi&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;msubsup&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mrow&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;iO&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;quartz&lt;/mi&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;4147&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;555&lt;/mn&gt;&lt;/mrow&gt;&lt;/mf","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"673 ","pages":"Article 122518"},"PeriodicalIF":3.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142815832","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}