Chemie Der Erde-Geochemistry最新文献

{"title":"Detrital zircon and rutile U–Pb dating of garnet-mica schist in the Istranca (Strandja) Massif (NW Türkiye): Mineral chemistry and metamorphic conditions","authors":"Ersin Kaygısız ,&nbsp;Namık Aysal ,&nbsp;Kıymet Deniz Yağcıoğlu","doi":"10.1016/j.chemer.2024.126172","DOIUrl":"10.1016/j.chemer.2024.126172","url":null,"abstract":"<div><div>The Strandja Massif is one of the important metamorphic Massifs of Türkiye. The Strandja Massif consists of metasedimentary, and metamagmatic rocks such as migmatite, ortho- and paragneiss, metagranite, garnet-mica-schist, calcschist and marbles. For the first time, mineral chemistry analyzes of garnet-mica schists were performed to better understand the degree of metamorphism, and possible P-T conditions were defined in the north-northwest of the Strandja Massif. Based on almandine garnet and Fe-biotite mineral chemistry, garnet bearing mica-schist are affected by lower amphibolite facies metamorphism under 6.1 kbar pressure and approximately 547 °C. Moreover, detrital zircon U<img>Pb dating was performed on 107 points to describe the maximum depositional age of this garnet-mica schist. The youngest zircon ²⁰⁶Pb/²³⁸U age obtained as 198 ± 17 Ma (98 % concordant, Th/U = 0.74) and the oldest ²⁰⁶Pb/²³⁸U age yielded as 1896.8 ± 33.4 Ma (100.12 % compatible, Th/U = 0.63). Additionally, a zircon U<img>Pb concordia protolith age of 302.33 ± 1.79 Ma was obtained from orthogneisses. In-situ rutile-in garnet U<img>Pb dating shows that garnet-mica schists underwent metamorphism at 119 ± 49 Ma. P-T conditions and age of metamorphism show that these rocks effected by the lower amphibolite facies metamorphism during late Jurassic – early Cretaceous period.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126172"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142255628","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}

{"title":"3D mineral prospectivity modeling using deep adaptation network transfer learning: A case study of the Xiadian gold deposit, Eastern China","authors":"Jin Chen ,&nbsp;Xin Zuo ,&nbsp;Zhankun Liu ,&nbsp;Liqun Jiang ,&nbsp;Yuezhi Li ,&nbsp;Zhengkai Fu ,&nbsp;Hao Deng ,&nbsp;Xiancheng Mao","doi":"10.1016/j.chemer.2024.126189","DOIUrl":"10.1016/j.chemer.2024.126189","url":null,"abstract":"<div><div>Mineralization distribution is commonly heterogeneous in space due to the various geology and structure conditions or fluid flow and evoluation, causing the possible difference in mineralization distribution regularity between shallow and deep at a deposit. This presents important challenges for three-dimensional mineral prospectivity modeling (3D MPM) for deep zones with the scarcity data conditions. Transfer learning has shown promising generalization performance in tasks involving shifts in data distribution, reducing reliance on labeled samples and enhancing learning capability with limited data. In this study, we propose an approach of 3D MPM, namely DAN-CBAM, based on the deep adaptation network (DAN) augmented with the convolutional block attention module (CBAM). It theoretically can harmonize the distribution of ore-controlling features between shallow and deep zones of deposits while effectively extract critical high-dimensional features and spatial patterns. The Xiadian orogenic gold deposit was selected as a case study to validate the approach. The DAN integrates multi-layer, multi-kernel adaptation at the top layer of the CNN, resulting in improved alignment of marginal distributions across domains. Metrics for distribution similarity such as Wasserstein distance, were reduced by 0.250 and KL divergence decreased by 0.032. Additionally, the inclusion of the CBAM module led to a lower MK-MMD loss and a faster convergence rate. And the DAN-CBAM model achieves superior prediction accuracy (0.85) compared to traditional deep neural network (DNN) models (0.81). These highlight CBAM's effectiveness in enhancing the model's ability to capture spatial similarities in mineralization. Furthermore, the area under the curve (AUC) value of the DAN-CBAM model (0.869) significantly outperforms traditional machine learning methods, including CNN (0.786) and Random Forest (0.703) models, underscoring its superior predictive efficiency in 3D MPM for deep mineralization. Therefore, the proposed DAN-CBAM model is promising to be applied in the 3D MPM, in particular for the deposits with different mineralization distribution regularities in space.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126189"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140137","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}

{"title":"The first finding of a highly evolved Mg-rich carbonatite intrusion in NW Anatolia (Arıklı-Çanakkale)","authors":"Ali Tugcan Unluer ,&nbsp;Zeynep Doner ,&nbsp;Alp Ünal ,&nbsp;Omer Kamaci ,&nbsp;Mustafa Kaya ,&nbsp;Sercan Ozturk ,&nbsp;Mustafa Kumral","doi":"10.1016/j.chemer.2024.126124","DOIUrl":"10.1016/j.chemer.2024.126124","url":null,"abstract":"<div><div><span><span><span>The carbonatite-alkaline rock suites are quite unique for hosting high grade critical metals including rare earth elements (REE), niobium (Nb), tantalum (Ta), thorium (Th) and uranium (U). Most of these rock suites are generally associated with continental rifting in overthickened </span>Precambrian<span><span> cratonic environments. In Turkey, despite majority of magmatism is quite young, a few number of </span>carbonatite intrusions were identified in Central Anatolian Crystalline block. However, the scientific literature which focused on the magmatic activities of NW Anatolia with its numerous articles involving magmatic intrusions and their extrusive counterparts lacked genuine magmatic carbonatite data until the present day. The Arıklı carbonatite intrusion is the first magmatic carbonatite identified in NW Anatolia, and also interesting for its unusual mineralogical and geochemical features. The carbonatite body is generally composed of multiple phases of </span></span>calcite<span> and apatite mineralizations. Carbonatitic rocks of Arıklı show a highly evolved nature with considerable Mg and Ca contents accompanied by Th (up to 0.36 wt%), U (up to 373.6 ppm) and heavy rare earth elements (HREE) (up to 194.7 ppm). The δ</span></span>¹³C (PDB) and δ¹⁸<span>O (SMOW) values show that fractional crystalization and hydrothermal activities<span> effected the composition of initial carbonatitic melt. The metasomatic halo of Arıklı carbonatites are enriched in terms of K (up to 12 wt%), P (up to 9 wt%), Th (248 ppm), and U (up to 0.27 wt%). However, the LREE values of both carbonatites and metasomatic rocks are pretty low compared to other carbonatite-fenite complexes. The effects of magmatic and post-magmatic events (partial melting, fractional crystalization, liquid immiscibility, and fenitization) played an important role in the formation of Arıklı carbonatite intrusion.</span></span></div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126124"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140777976","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}

{"title":"Mineralization characteristics of Lead-Zinc-Copper deposits in Akdağmadeni Region (Northern Central Anatolia, Türkiye): Integration of field study, geochemical, isotope, and geophysical data","authors":"Ahmet Gökce ,&nbsp;Oktay Canbaz ,&nbsp;Esra Ünal Çakır ,&nbsp;Gülcan Bozkaya ,&nbsp;Özcan Bektaş ,&nbsp;Orbay Başdelioğlu","doi":"10.1016/j.chemer.2024.126201","DOIUrl":"10.1016/j.chemer.2024.126201","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The Akdağmadeni region is one of the important Pb-Zn-Cu metallogenic provinces in Türkiye. Most of the Pb-Zn-Cu deposits in the region are located near granitoid intrusions within metamorphic rocks, and they are typically classified as skarn-type ores associated with granitoids. However, no relationship has been determined between the Başçatak prospect and any granitoid outcrop. This raises the question of whether the Pb-Zn-Cu mineralization in the region is related to granitoids or if magmatic processes remobilized pre-existing mineralization. Observations from field studies suggest that mineralization in the Başçatak prospect is a stratiform type, metamorphosed occurrence that might have occurred earlier than the granitic intrusions. The geochemical data indicated that the granitoids have low-grade, subeconomic Cu potential and no Zn productivity potential, supporting these observations. Geophysical data also show that there is no intrusive body beneath this prospect. Granitoid-related deposits (Karapir - Ortaköy and Akçakışla) exhibit two distinct occurrences around the contact between the granite and the surrounding metamorphic rocks. The first type of occurrence (O-1) is formed at the contact and contains magnetite, pyrrhotite, and chalcopyrite. The second type of occurrence (O-2) is located outside the contact and is rich in sphalerite and galena. Both O-1 and O-2 contain skarn minerals along with ore minerals. The δ&lt;sup&gt;34&lt;/sup&gt;S values of sulfide minerals from the deposits range from −0,7 to 7,5 ‰ (V-CDT). These values overlap with those of both magmatic sulfur and reduced sulfur from seawater-dissolved sulfate, making it difficult to suggest a sulfur source without additional data. Lead isotope compositions of the galenas from all deposits plot above the average crustal growth curve, suggesting an upper crustal and orogenic source similar to Western Mediterranean and Türkiye type materials described in the literature for the lead, source in different time intervals. Furthermore, Pb isotope geochemistry suggests a contemporaneous age with the host metamorphic rocks (Carboniferous – Lower Permian) for the Başçatak prospect. These results support observations indicating a &lt;em&gt;syn&lt;/em&gt;-genetic formation for the Başçatak prospect. The age range of granite-related deposits forms two sub-groups:105–77 Ma and 61–50 Ma corresponding to the Upper Cretaceous and Paleocene transition. These data indicate that that the galenas were formed in two different stages in these mineralizations. Stratiform mineralization in the Başçatak prospect likely formed either through exhalative sedimentary processes by hydrothermal fluids or through chemical sedimentary processes under reductive conditions in a marine environment during metamorphism. O-1 appears to have been formed by hydrothermal fluids developed during granitic magmatism. A plausible formation process for O-2 involves the leaching of sulfur, lead and other metals from Başçatak type enrichm","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126201"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140132","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}

{"title":"Nephelinites from Burko volcano (Tanzania) record the phase relations among perovskite, magnetite, titanite and andradite in evolved alkaline and silica-undersaturated systems","authors":"Fabian Schmitt ,&nbsp;Michael A.W. Marks ,&nbsp;Michelle Siegel ,&nbsp;Mika Henzler ,&nbsp;Anatoly N. Zaitsev ,&nbsp;Gregor Markl","doi":"10.1016/j.chemer.2024.126211","DOIUrl":"10.1016/j.chemer.2024.126211","url":null,"abstract":"<div><div>Nephelinitic rocks from Burko volcano in the Northern Tanzanian Divergence Zone of the East African Rift System represent transitional compositions between primitive and evolved nephelinites which exhibit two distinct phase assemblages, allowing to constrain the magmatic history of such particular rock types. Detailed petrography, mineral compositions and whole rock geochemistry were used to reconstruct the crystallization conditions and the petrological evolution of the Burko rocks and to compare them to the nearby volcanoes of Oldoinyo Lengai and Sadiman. Burko samples report a characteristic mineralogy of intermediate nephelinites (Mg# of 60–40) which comprise nepheline-diopside-magnetite-perovskite assemblages. They evolved mainly via fractionation of clinopyroxene, apatite, magnetite, and perovskite/titanite to peralkaline nephelinites (Mg# of 40–25) comprising nepheline-aegirine-augite-titanite-andradite±K-feldspar assemblages. The presence of unexposed primitive olivine nephelinites is, however, indicated by rare forsterite antecrysts.</div><div>Reworking of crystal mushes and/or magma mixing are evident from different xenocrysts, antecrysts and pyroxenitic–ijolitic inclusions, precluding simple fractional crystallization modelling. The evolution from diopside-bearing nephelinites towards aegirine-augite-bearing ones was accompanied by a decrease in temperature (from ~1100 to ~900 °C) and an increase of log(<em>a</em>SiO₂) towards ~−0.5 and of <em>f</em>O₂ (∆FMQ ~2.5 to ~3). Especially in the peralkaline nephelinites, late-stage enrichment of Sr, Ba and halogens is documented by Sr-and F-rich apatite, barytolamprophyllite, celsian, götzenite, and eudialyte. In comparison, evolved and mostly peralkaline nephelinites from the nearby Oldoinyo Lengai and Sadiman volcanoes contain similar mineral assemblages, indicating comparable formation processes, but slightly different melt evolution trajectories. The variations in nephelinite composition and phase assemblages are linked to a) slightly different parental melt compositions related to variable amounts of amphibole, mica and carbonate in the molten mantle veins and b) different crystallization conditions, especially redox conditions, during cooling.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126211"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Magma nature and tectono-magmatic context of the Eocene Uludağ granitoids (NW-Türkiye): Insights into the Cenozoic geodynamics of the Tethyan Orogenic Belt","authors":"Hüseyin Kocatürk ,&nbsp;Mustafa Kumral ,&nbsp;Robert A. Creaser ,&nbsp;S. Andrew DuFrane ,&nbsp;Ali Tuğcan Ünlüer ,&nbsp;Hüseyin Sendir ,&nbsp;Zeynep Döner ,&nbsp;Mustafa Kaya ,&nbsp;Şenel Özdamar ,&nbsp;Amr Abdelnasser","doi":"10.1016/j.chemer.2024.126170","DOIUrl":"10.1016/j.chemer.2024.126170","url":null,"abstract":"<div><div>Late Paleocene to Middle-Eocene magmatism provides critical insights into the reconstruction of the Cenozoic geodynamic evolution of NW Anatolia. In this study, we mapped individual petrographic facies from the Eocene Uludağ Plutons (Topuk and Tepeldağ) and present zircon U-Pb geochronology, Sr-Nd isotope data, and comprehensive geochemical analyses for the entire plutons. We examined the Delice tonalite-granodiorite (D4) and Delice alkali-feldspar granite (D8) from the Topuk Pluton, as well as the Southern Tepeldağ quartz-monzodiorite (ST1) from the Tepeldağ Pluton. U-Pb zircon ages were 54.56 ± 0.21 Ma for ST1, 47.35 ± 0.21 Ma for D4, and 45.90 ± 0.29 Ma for D8. Initial ⁸⁷Sr/⁸⁶Sr and ¹⁴⁴Nd/¹⁴³Nd values were calculated, showing 0.706693 and 0.512428 for ST1, 0.707309 and 0.512452 for D4, and 0.705896 and 0.512448 for D8, respectively. The new zircon U-Pb ages for these facies cover nearly the entire interval from 54 to 45 Ma, enabling a comparison of magma evolution with the Late Paleocene to Middle-Eocene (58–45 Ma) magmatism.</div><div>Locally, patterns of magma replenishment, early-stage plagioclase accumulation, and later-stage dominance of amphibole fractional crystallization suggest a shift to fluid-related magma sources and sustained fluid release from the subducting Neotethys slab. Although changes in magma nature are common to both slab rollback and slab break-off, a comparative evaluation of Late Paleocene to Middle-Eocene granitoids supports continuous subduction and slab rollback for the Cenozoic geodynamic evolution of NW Anatolia. Continuous, systematic changes in magma character, a gradual decrease in Moho depth, and continuous tectonic shifts and evolution collectively indicate ongoing subduction and slab rollback dynamics rather than abrupt cessation. Our model for Western Anatolia proposes that early shallow subduction transformed into prolonged slab rollback in the west and early slab rollback transitioned to a more stable slab steepening regime in the east, shaping the tectono-magmatic evolution across the region.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126170"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187187","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}

{"title":"Mineral chemistry and P–T conditions of the winchite-bearing metabasic rocks in the NE edge of the Menderes Massif (Western Türkiye)","authors":"Zeynep Özbey ,&nbsp;Namık Aysal ,&nbsp;Şemsettin Caran ,&nbsp;Fatma Şişman Tükel ,&nbsp;Kıymet Deniz Yagcioglu ,&nbsp;Mehmet Yesiltas ,&nbsp;İsak Yılmaz","doi":"10.1016/j.chemer.2024.126126","DOIUrl":"10.1016/j.chemer.2024.126126","url":null,"abstract":"<div><div><span>The Menderes massif is a large metamorphic crystalline complex located in western Turkey. The massif consists of late Neoproterozoic basement (core) rocks and Palaeozoic<span><span> - Cenozoic cover units that have undergone by high- and low-grade polyphase metamorphisms. Palaeozoic to Mesozoic cover units cropped out in the NE edge of the massif (east of Sivaslı) are overlaid tectonically by upper Cretaceous<span><span> meta-ophiolitic rocks. The meta-ophiolitic unit comprises blocks mainly of metabasalt, </span>metagabbro, metadiorite and metaultramafite within an intensively sheared </span></span>serpentinite<span> matrix. It also includes blocks of epidote-actinolite-schist and tremolite-actinolite-schist, which originated from basic rocks, as well as chlorite schist blocks, which originated from ultramafic rocks<span>. Sodic-calcic amphiboles recorded in the samples of metabasalt block taken from the marble-metabasalt block boundary, at the tectonic contact where the meta-ophiolitic rocks overlap the underlying marble sequence. Sodic-calcic amphiboles were classified into winchite and ferri-winchite with relatively homogeneous </span></span></span></span>^TSi (7.35–8.01 a.p.f.u.), and X_Mg<span> (0.69–0.80) values. P-T conditions were estimated to be around 300–400 °C and 5–6 kb based on the mineral chemical analyses of the sodic-calcic amphiboles. According to these values, the NE edge of the Menderes Massif must have undergone metamorphism under a medium-pressure (MP) greenschist facies.</span></div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126126"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141059908","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}

{"title":"Geochronology and petrochemistry of Karabiga pluton in western Sakarya Zone (NW Turkey): Implications from new zircon U-Pb and biotite Ar/Ar ages, Sr-Nd isotope data and bulk-rock geochemistry","authors":"Şenel Özdamar ,&nbsp;Oral Sarıkaya ,&nbsp;Naşide Merve Sütçü ,&nbsp;Haibo Zou ,&nbsp;Sarah Sherlock","doi":"10.1016/j.chemer.2023.126052","DOIUrl":"10.1016/j.chemer.2023.126052","url":null,"abstract":"<div><div><span><span><span><span>The closure of the Neo-Tethys Ocean and the following continental collision produced extensive Eocene-aged granitic plutons in the northern margin of </span>Gondwana. This paper deals with the </span>geochronology<span><span> and petrogenesis<span><span> of the Karabiga pluton in western Sakarya Zone. The pluton comprises K-feldspar, plagioclase, hornblende, biotite, quartz and accessory minerals (e.g., </span>titanite<span>, zircon, </span></span></span>apatite<span><span>, opaques), and secondary minerals such as chlorite, sericite, epidote, carbonate and clay minerals. Laser ablation inductively coupled plasma mass spectrometer zircon U-Pb dating yielded perfect ages of 48.27 ± 0.21 and 47.06 ± 0.32 Ma, indicating that the pluton were emplaced in the Early </span>Eocene. Our results indicate that Ti-in-zircon temperature (ca. 900 °C), which is consistent with zircons grew in the </span></span></span>continental crust, are higher than zircon saturation temperatures (740–884 °C). </span>⁴⁰Ar/³⁹Ar dating of biotites of the pluton yielded cooling ages between 47.34 ± 0.43 Ma and 46.30 ± 0.52 Ma. These dates are interpreted as the cooling age of the Karabiga pluton. The pluton is characterized by high SiO₂ (72.40–76.48 wt%), K₂O (5.12–6.44 wt%) and Na₂<span>O (3.26–5.55 wt%) contents and exhibit enriched LREEs, K, Rb, Th, U, and Pb, and depleted Nb, Ta, P, and Ti contents. It belongs to shoshonite series, and displays peraluminous, I-type character. </span>⁸⁷Sr/⁸⁶S_(i) ratios of the pluton vary between 0.703296 and 0.706654, while those of ¹⁴³Nd/¹⁴⁴Nd_(i)<span> lie between 0.512596 and 0.512629. In conclusion, Karabiga pluton could be originated from dehydration-melting of metagreywacke<span> and metapelites in middle-upper crust due to slab breakoff/delamination and major, trace element contents, decreasing Al</span></span>₂O₃, Fe₂O₃, MgO and TiO₂ with increasing SiO₂<span> as well as initial Sr-Nd homogenity show that fractional crystallization played a role in the evolution of the pluton.</span></div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126052"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138566568","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}

{"title":"Were South India and North China Craton attached during the Paleoproterozoic (Orosirian) Nuna Assembly? Novel geochemical and isotopic investigations of A2-type granites from the Khammam Schist Belt, Eastern Dharwar Craton, India","authors":"Ab Majeed Ganaie ,&nbsp;Kausik Satpathi ,&nbsp;Keewook Yi ,&nbsp;Jeong Youn-Joong ,&nbsp;Pritam Nasipuri","doi":"10.1016/j.chemer.2024.126178","DOIUrl":"10.1016/j.chemer.2024.126178","url":null,"abstract":"<div><div>The paper presents novel geochemical and geochronological data from granites in Khammam, Eastern Dharwar Craton (EDC), India. The studied granites contain major mineral phases like quartz, alkali-feldspar, plagioclase, biotite, and muscovite in decreasing order of abundance. The accessory phases are epidote, titanite, and zircon. The samples comprise 70 ‐–77 wt% SiO₂ and 12–15 wt% Al₂O₃. The K₂O and Na₂O concentrations range from 2.57 to 5.65 wt% and 1.17 to 2.69 wt%, respectively. They are enriched in Rb, Th, and Pb and depleted in Nb, Ta, and Ti. On a chondrite-normalized plot, the samples exhibit a rightward trend with a negative Eu anomaly. Zircon saturation in silicate melts yields a temperature (T_Zr) of 859 ‐ 978 °C. The microstructure and U - Pb isotopic analysis of zircon grains (<em>n</em> = 79) reveals the presence of magmatic and polymetamorphic grains with ²⁰⁷Pb/²⁰⁶Pb age clusters at 1844 Ma (number of analyses, <em>n</em> = 7) - 1858 Ma (<em>n</em> = 8), 1737 Ma (<em>n</em> = 5) -1768 Ma (<em>n</em> = 4), 1619 Ma (n = 7) - 1634 Ma (<em>n</em> = 6), and 1554 Ma (n = 5), respectively. The magmatic zircons exhibit ε(Hf) values between 3 and 18.9 with a two-stage model age of 2.03 Ga. In contrast, the metamorphic zircons exhibit ε(Hf) values between −5.6 and 18, yielding a two-stage model age of 1.97 Ga. The geochemical and geochronological studies indicate that the rocks are A₂-type granite emplaced during the accretion of the eastern block of the North China Craton (NCC) and EDC between 1844 Ma and 1858 Ma. The zircons from 1737–1768 Ma and 1620 Ma show the time of metamorphic growth during Antarctica-Nellore Schist Belt (EDC) accretion. Finally, the U-Pb zircon ages from 1554 Ma represent Nuna's final amalgamation. The results of this study posit an association between EDC and NCC during Nuna assembly.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126178"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142255626","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}

{"title":"Paleoclimate and paleodepositional condition of Ekizköy (Muğla-Milas) Middle Miocene coals: Implications from biomarker data","authors":"Fatma Hoş Çebi","doi":"10.1016/j.chemer.2024.126177","DOIUrl":"10.1016/j.chemer.2024.126177","url":null,"abstract":"<div><div>In this study, saturated, aromatic biomarker distributions and organic geochemical characteristics and depositional environments of Middle Miocene aged coals in Ekizköy (Muğla-Milas) region were investigated. The average TOC, HI and OI values are 46.24 %, 153 mg HC/gTOC and 77 mg CO₂/gTOC, respectively. Pr/Ph ratio is 0.9 and Pr/C₁₇ and Ph/C₁₈ are 0.2 and 0.3. Considering the paleoclimate data (TOC, CPI, ACL, P_<em>wax</em>, P_<em>aq</em>, Q_{<em>wood/grass</em>}, Q_{<em>grass/plant</em>} and Q_{<em>wood/plant</em>}), it is likely that the climate was moderately humid and hot for the period represented by sample M-4 and relatively more humid and temperate for the period represented by sample M-8. High C₂₉(C₂₈ + C₂₉) MA steroid ratio indicates that Ekizköy coals are composed of terrestrial OM (Organic Matter). 20S/(20R + 20S) (for C₂₉), 22S/(22R + 22S) homohopane (for C₃₁), ββ/(αα + ββ) sterane, moretane/hopane ratios that show the maturity of OM are indicative of immature OM. C₂₈TA/(C₂₉MA + C₂₈TA) steroid and MA(I)/MA(I + II), TA(I)/TA(I + II), MDR, MPI, MPR ratios obtained from aromatic biomarkers are low and show an immature character. Since coals contain Type III kerogen and immature organic matter, they can only generate gas under appropriate temperature and pressure. Saturated and aromatic biomarker data in Ekizköy coals show that they precipitate in a lacustrine environment dominated by suboxic conditions.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126177"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142255596","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}