Hussain M., Rehman H.U., Kakar M.I., Lee H.Y., Chung S.L., Das K., Rashid M.u., Ahmad N., Zafar T., Yamamoto H. . Zircon U-Pb, Hf isotope and trace element geochemistry from the newly found Ne2026 · 担当区分： 筆頭著者, 最終著者, 責任著者 記述言語： 日本語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： Precambrian Research This study investigates the newly found granitoids on the western margin of the Indian Plate, exposed in the Wadh-Khuzdar area of Balochistan, Pakistan. The emplacement of these granitoids has important implications for understanding the tectonic evolution of the Rodinia Supercontinent during the Neoproterozoic era. To understand magma genesis and tectonic settings, detailed petrography, whole-rock geochemistry, zircon U-Pb/Lu-Hf isotope analyses, and trace element geochemistry were conducted. In total, 50 rock samples were collected from two exposed bodies of granitoids. The studied rocks are K-feldspar rich, exhibit high K<inf>2</inf>O + Na<inf>2</inf>O contents (6.2–11.5 wt%), and display geochemical characteristics similar to A-type granitoids which are generally silica-rich, show relatively higher contents of alkalis, FeO/(FeO + MgO), rare-earth elements, and Ga/Al ratios but low Eu anomalies, Al<inf>2</inf>O<inf>3</inf>, Sr Ba, and Ti. Their chemistry reflect high-T/low P formation conditions, typical of intra-plate rifting and post-collisional setting. From 10 representative samples, 154 zircon grains (8 from Eastern and 2 samples from Western body) were investigated for internal structures, and analyzed for U-Pb isotope, trace element geochemistry, and Lu-Hf isotope analysis on selected dated spots. The studied zircons exhibit oscillatory zoning, showed higher Th/U ratios of 0.4 to 1.4, and displayed steep chondrite-normalized rare-earth element patterns, positive Ce and negative Eu anomalies all indicate their magmatic origin. The U-Pb zircon ages (630 to 753 Ma), εHf(t) values of + 9.4 to 15.2, zircon-saturation temperatures from whole-rock (695 to 1031 °C), Ti-in-zircon values (716 to 1017 °C), suggest their magmatic crystallization from juvenile crust derived from a depleted mantle source. Subduction-related arc-type, rift-related/within-plate, and mantle upwelling played a crucial role to generate these granitoids. Similarities in petrography, ages, and Hf isotope data provide a strong link that the studied granitoids generated from a coeval magma, in the same tectonic regime, which generated several other granitoid of the region that include the Malani Igneous Suite in India, Nagar Parkar Igneous Complex in Pakistan, Seychelles, and Madagascar. All these Neoproterozoic granitoids formed from magmatism related to the subduction of the Mozambique Ocean, followed by a rift and extensional tectonic regime within and along the western margin of the Rodinia supercontinent. DOI： 10.1016/j.precamres.2026.108117 Scopus
Rehman H.U. . Zircon Internal Deformation and Its Effect on U-Pb Geochronology: A Case Study from the Himalayan High-Pressure Eclogites . Minerals14 ( 8 )2026 · 担当区分： 筆頭著者, 最終著者, 責任著者 記述言語： 英語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： Minerals Zircon, with a chemical formula of ZrSiO4, is a widely used mineral for determining the crystallization age of igneous rocks. It is also used to constrain the timing of metamorphic events from its overgrowth or recrystallized domains. Furthermore, detrital zircon grains can provide information on the sedimentary provenance. Due to the trace amounts of uranium (parent) which decays into its daughter element (Pb), it is a prime geochronometer for the majority of magmatic and metamorphic rocks. With high-precision analytical instruments, such as TIMS, SIMS, and LA-ICP-MS, huge amounts of geochronological and trace element data from zircon have been generated around the globe to date. Target domains within zircon grains are analyzed to extract geochemical and geochronological records using spatially resolved techniques such as ion probes or laser ablation coupled with mass spectrometry. Before any such analysis, the zircon grains are examined for internal structures, growth zoning, and the presence of tiny inclusions. However, many researchers analyze multiple domains within single zircon grains for U-Pb isotope analysis with little regard for their internal structures, particularly crystallographic orientations. Hence, they may obtain mixed ages with variable discordance, leading to imprecise interpretation especially when the growth domains are not well-identified. Particularly, zircon grains that contain multi-growth domains or have local internal deformations within a single grain may not produce geologically meaningful age results if the analyses are conducted on mixed domains. This study presents a brief review on zircon geochronology, how to identify and visualize micro-deformations in metamorphic zircons through the EBSD analysis, and the effects of micro-deformation on age results. Examples from a case study conducted on zircons hosted in the Himalayan high-pressure eclogites are presented that show intra-grain plastically deformed domains and their effects on the corresponding age results. DOI： 10.3390/min14080742 Scopus
Hussain A., Zhao K.D., Rehman H.U., Li Q., Hussain S.A., Hussain Z., Zafar T., Moradi S., Widory D. . Geochronology and petrogenesis of alkaline rocks from the Peshawar Plain Alkaline Igneous2025 · 記述言語： 日本語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： Lithos Alkaline rocks of the Peshawar Plain Alkaline Igneous Province (PPAIP) constitute a major magmatic unit within the Indian plate in northwestern Pakistan. However, their tectonic settings, petrogenesis, and potential for associated rare metal mineralization remain poorly constrained. In this study, we present U[sbnd]Pb zircon ages, mineral and whole-rock geochemical data, and Nd[sbnd]Hf isotope compositions for the Baru granite and its associated pegmatite, providing new insights into their origin. Zircon U[sbnd]Pb dating of the Baru granite and the pegmatite yielded crystallization ages of 270.6 ± 1.7 Ma and 270.3 ± 1.5 Ma, respectively. Zircon grains exhibit positive ɛ<inf>Hf</inf>(t) values, ranging from +4.1 to +7.3 for the Baru granite and from +5.2 to +10.0 for the pegmatite. The nearly identical ages and highly similar Hf isotope compositions indicate a co-magmatic origin for the granite and the pegmatite. Geochemically, the Baru granite is characterized by high SiO<inf>2</inf>, Rb, Nb, U, and Ta contents, low Yb/Ta, Y/Nb ratios, and positive bulk-rock ɛ<inf>Nd</inf>(t) values (+2.8 to +4.5). These features are consistent with fractionated anorogenic A-type granites derived from an OIB-like mantle source. Trace element compositions of zircons from the granite and the pegmatite exhibit systematic evolutionary trends, including increasing concentrations of HREEs, Hf, U, Y, Nb, and Ta, coupled with decreasing Eu anomalies and Ti concentrations. These trends strongly suggest that prolonged fractional crystallization of an alkaline magma, progressing from the granite to the pegmatite, was responsible for the enrichment of rare metals in the residual pegmatitic melt. The Baru granite shares similar emplacement ages and Hf[sbnd]Nd isotope compositions with other Permian alkaline rocks in the NW Himalaya, southern Qiangtang, and Tibet. This spatial and temporal correlation implies that these alkaline rocks formed within a large-scale extension regime across the Tethys realm. This early Permian magmatic event was likely triggered by a mantle plume, which played an active role during rifting along the northern margin of Gondwana. DOI： 10.1016/j.lithos.2025.108271 Scopus
Study of the nano-scale plastic deformation in zircon: application to meaningful geochronology2022 · 配分額： 3900000円 （ 直接経費： 3000000円 、 間接経費： 900000円 ） Rock samples collected during the past field surveys are under investigation currently. Petrography, mineral chemistry and Zircon EBSD analysis on some thin sections from high and ultrahigh-temperature granulites have been conducted and the work is still in progress. Samples collected from the local field survey have been also investigated for petrography. Zircon identification has been done for some samples and further work is in progress. <BR> Some of the research results have been summarized in a manuscript, which is planned for submission to an international scientific journal within April, 2022. <BR> In addition, an abstract related to the zircon EBSD data has been submitted for the 14th International eclogite conference that will be held in July, 2022. Research results will be presented at the above-mentioned conference.
