{"title":"伊朗 UDMA 北部 Hesar 板块的矿物化学、微量元素、同位素分析和锆石 U-Pb 定年:碰撞前岩浆混合的含义","authors":"Kazem KAZEMI, Soroush MODABBERI, Parisa GHARIBNEJAD, Yilin XIAO, Fatemeh SARJOUGHIAN, Ali KANANIAN","doi":"10.1111/1755-6724.15118","DOIUrl":null,"url":null,"abstract":"<p>The Hesar pluton in the northern Urumieh–Dokhtar magmatic arc hosts numerous mafic-microgranular enclaves (MMEs). Whole rock geochemistry, mineral chemistry, zircon U-Pb and Sr-Nd isotopes were measured. It is suggested that the rocks are metaluminous (A/CNK = 1.32–1.45), subduction-related I-type calc-alkaline gabbro to diorite with similar mineral assemblages and geochemical signatures. The host rocks yielded an U-Pb crystallization age of 37.3 ± 0.4 Ma for gabbro-diorite. MMEs have relatively low SiO<sub>2</sub> contents (52.9–56.6 wt%) and high Mg<sup>#</sup> (49.8–58.7), probably reflecting a mantle-derived origin. Chondrite- and mantle-normalized trace element patterns are characterized by LREE and LILE enrichment, HREE and HFSE depletion with slight negative Eu anomalies (Eu/Eu* = 0.86–1.03). The host rocks yield (<sup>87</sup>Sr/<sup>86</sup>Sr)<sub>i</sub> ratios of 0.70492–0.70510, positive <i>ε</i><sub>Nd</sub>(<i>t</i>) values of +1.55–+2.06 and <i>T</i><sub>DM2</sub> of 707–736 Ma, which is consistent with the associated mafic microgranular enclaves ((<sup>87</sup>Sr/<sup>86</sup>Sr)<sub>i</sub> = 0.705014, <i>ε</i><sub>Nd</sub>(<i>t</i>) = +1.75, <i>T</i><sub>DM2</sub> = 729 Ma). All data suggest magma-mixing for enclave and host rock formation, showing a complete equilibration between mixed-mafic and felsic magmas, followed by rapid diffusion. The <i>T</i><sub>DM1</sub>(Nd) and <i>T</i><sub>DM2</sub>(Nd) model ages and U-Pb dating indicate that the host pluton was produced by partial melting of the lower continental crust and subsequent mixing with injected lithospheric mantle-derived magmas in a pre-collisional setting of Arabian–Eurasian plates. Clinopyroxene composition indicates a crystallization temperature of ∼1000°C and a depth of ∼9 km.</p>","PeriodicalId":7095,"journal":{"name":"Acta Geologica Sinica ‐ English Edition","volume":null,"pages":null},"PeriodicalIF":3.5000,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Mineral Chemistry, Trace Elements, Isotopic Analysis and Zircon U-Pb Dating in the Hesar Pluton, Northern UDMA, Iran: Implications for Pre-Collisional Magma Mixing\",\"authors\":\"Kazem KAZEMI, Soroush MODABBERI, Parisa GHARIBNEJAD, Yilin XIAO, Fatemeh SARJOUGHIAN, Ali KANANIAN\",\"doi\":\"10.1111/1755-6724.15118\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>The Hesar pluton in the northern Urumieh–Dokhtar magmatic arc hosts numerous mafic-microgranular enclaves (MMEs). Whole rock geochemistry, mineral chemistry, zircon U-Pb and Sr-Nd isotopes were measured. It is suggested that the rocks are metaluminous (A/CNK = 1.32–1.45), subduction-related I-type calc-alkaline gabbro to diorite with similar mineral assemblages and geochemical signatures. The host rocks yielded an U-Pb crystallization age of 37.3 ± 0.4 Ma for gabbro-diorite. MMEs have relatively low SiO<sub>2</sub> contents (52.9–56.6 wt%) and high Mg<sup>#</sup> (49.8–58.7), probably reflecting a mantle-derived origin. Chondrite- and mantle-normalized trace element patterns are characterized by LREE and LILE enrichment, HREE and HFSE depletion with slight negative Eu anomalies (Eu/Eu* = 0.86–1.03). The host rocks yield (<sup>87</sup>Sr/<sup>86</sup>Sr)<sub>i</sub> ratios of 0.70492–0.70510, positive <i>ε</i><sub>Nd</sub>(<i>t</i>) values of +1.55–+2.06 and <i>T</i><sub>DM2</sub> of 707–736 Ma, which is consistent with the associated mafic microgranular enclaves ((<sup>87</sup>Sr/<sup>86</sup>Sr)<sub>i</sub> = 0.705014, <i>ε</i><sub>Nd</sub>(<i>t</i>) = +1.75, <i>T</i><sub>DM2</sub> = 729 Ma). All data suggest magma-mixing for enclave and host rock formation, showing a complete equilibration between mixed-mafic and felsic magmas, followed by rapid diffusion. The <i>T</i><sub>DM1</sub>(Nd) and <i>T</i><sub>DM2</sub>(Nd) model ages and U-Pb dating indicate that the host pluton was produced by partial melting of the lower continental crust and subsequent mixing with injected lithospheric mantle-derived magmas in a pre-collisional setting of Arabian–Eurasian plates. Clinopyroxene composition indicates a crystallization temperature of ∼1000°C and a depth of ∼9 km.</p>\",\"PeriodicalId\":7095,\"journal\":{\"name\":\"Acta Geologica Sinica ‐ English Edition\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":3.5000,\"publicationDate\":\"2023-10-03\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Acta Geologica Sinica ‐ English Edition\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1111/1755-6724.15118\",\"RegionNum\":3,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"GEOSCIENCES, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta Geologica Sinica ‐ English Edition","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1111/1755-6724.15118","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
Mineral Chemistry, Trace Elements, Isotopic Analysis and Zircon U-Pb Dating in the Hesar Pluton, Northern UDMA, Iran: Implications for Pre-Collisional Magma Mixing
The Hesar pluton in the northern Urumieh–Dokhtar magmatic arc hosts numerous mafic-microgranular enclaves (MMEs). Whole rock geochemistry, mineral chemistry, zircon U-Pb and Sr-Nd isotopes were measured. It is suggested that the rocks are metaluminous (A/CNK = 1.32–1.45), subduction-related I-type calc-alkaline gabbro to diorite with similar mineral assemblages and geochemical signatures. The host rocks yielded an U-Pb crystallization age of 37.3 ± 0.4 Ma for gabbro-diorite. MMEs have relatively low SiO2 contents (52.9–56.6 wt%) and high Mg# (49.8–58.7), probably reflecting a mantle-derived origin. Chondrite- and mantle-normalized trace element patterns are characterized by LREE and LILE enrichment, HREE and HFSE depletion with slight negative Eu anomalies (Eu/Eu* = 0.86–1.03). The host rocks yield (87Sr/86Sr)i ratios of 0.70492–0.70510, positive εNd(t) values of +1.55–+2.06 and TDM2 of 707–736 Ma, which is consistent with the associated mafic microgranular enclaves ((87Sr/86Sr)i = 0.705014, εNd(t) = +1.75, TDM2 = 729 Ma). All data suggest magma-mixing for enclave and host rock formation, showing a complete equilibration between mixed-mafic and felsic magmas, followed by rapid diffusion. The TDM1(Nd) and TDM2(Nd) model ages and U-Pb dating indicate that the host pluton was produced by partial melting of the lower continental crust and subsequent mixing with injected lithospheric mantle-derived magmas in a pre-collisional setting of Arabian–Eurasian plates. Clinopyroxene composition indicates a crystallization temperature of ∼1000°C and a depth of ∼9 km.
期刊介绍:
Acta Geologica Sinica mainly reports the latest and most important achievements in the theoretical and basic research in geological sciences, together with new technologies, in China. Papers published involve various aspects of research concerning geosciences and related disciplines, such as stratigraphy, palaeontology, origin and history of the Earth, structural geology, tectonics, mineralogy, petrology, geochemistry, geophysics, geology of mineral deposits, hydrogeology, engineering geology, environmental geology, regional geology and new theories and technologies of geological exploration.