15 results on '"Hu, Ruizhong"'
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2. U-Pb zircon dating, Sr-Nd isotope and petrogenesis of Sarduiyeh granitoid in SE of the UDMA, Iran: implication for the source origin and magmatic evolution.
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Nazarinia, Asma, Mortazavi, Mohsen, Arvin, Mohsen, Hu, Ruizhong, Zhao, Chenghai, and Poosti, Mohammad
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RARE earth metals ,TRACE elements ,PLAGIOCLASE ,ZIRCON ,GEOLOGICAL time scales ,PETROGENESIS - Abstract
The Sarduiyeh granitoid (SG) is intruded in the southeastern part of the Dehaj-Sarduiyeh volcano-sedimentary belt in the southeastern end of the Urumieh-Dokhtar Magmatic Arc (UDMA) in Iran. The medium-to-coarse-grained granitoid unit, with granular texture consists mainly of diorite, tonalite, granodiorite and monzogranitic rocks. Mineralogically, these rocks consist mainly of plagioclase, K-feldspar, quartz, biotite and hornblende. The whole rock geochemical analyses indicates that the SG is calc-alkaline, I-type, metaluminous, enriched in large ion lithophile elements (LILE; such as K, Cs, Pb) and depleted in high field strength elements (HFSE; such as Ti, Nb, Ta, Zr). Chondrite normalized plot of SG rare earth elements (REE) show light rare earth element enrichments with (La
N /YbN = 2.44–8.68) and flat heavy rare earth element patterns with (GdN /YbN = 1.02–1.36). The rather high Y (av. 19.35 ppm), low Sr content (av. 293.76 ppm) and low Cr and Ni contents (av. 20.1 and 4.69 ppm, respectively) of the SG demonstrate its normal calc-alkaline and non-adakitic nature, the features of Jebal Barez-type granitoids. The geochemical characteristics and isotopic composition, low ISr (0.7046–0.7049) and positive ɛt Nd (+3.4 to +4.03) values, of the SG suggest that its parental magma formed as a result of partial melting from metabasic rocks of lower crust in a subduction-related arc setting. Fractionation of an assemblage dominated by plagioclase, K-feldspar, amphibole and magnetite may have been responsible for the evolution of the SG magma. U-Pb zircon geochronology gives an age of 27.95 ± 0.27 Ma for the SG, suggesting that the final collision between the Arabian plate and Central Iranian microcontinent may have happened in the Late Oligocene. [ABSTRACT FROM AUTHOR]- Published
- 2020
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3. Cenozoic Adakite-type Volcanic Rocks in Qiangtang, Tibet and Its Significance
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Wang Tian-wu, Liu Shen, Hu Ruizhong, Li Cai, Jin Wei, Feng Caixia, Chi Xiao-guo, and Yang Rihong
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Basalt ,Volcanic rock ,geography ,Underplating ,Fractional crystallization (geology) ,geography.geographical_feature_category ,Partial melting ,Adakite ,Geochemistry ,Geology ,Dacite ,Petrogenesis - Abstract
Volcanic rocks in the study area, including dacite, trachyandesite and mugearite, belong to the intermediate-acid, high-K calc-alkaline series, and possess the characteristics of adakite. The geochemistry of the rocks shows that the rocks are characterized by SiO259%, enrichment in A12O3(15.09-15.64%) and Na2O (3.6%), high Sr (649-885 μg/g) and Sc, low Y contents (17 μg/g), depletion in HREE (Yb1.22 μg/g), (La/Yb)N25, Sr/Y40, MgO3% (Mg0.35), weak Eu anomaly (Eu/Eu=0.84-0.94), and lack of the high field strength elements (HFSE) (Nb, Ta, Ti, etc.). The Nd and Sr isotope data (87Sr/86Sr=0.7062-0.7079, 143Nd/144Nd=0.51166-0.51253, eNd= -18.61-0.02), show that the magma resulted from partial melting (10%-40%) of newly underplated basaltic lower crust under high pressure (1-4 GPa), and the petrogenesis is obviously affected by the crust's assimilation and fractional crystallization (AFC). This research will give an insight into the uplift mechanism of the Tibetan plateau.
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- 2010
4. Petrogenesis and geodynamic setting of Early Cretaceous mafic–ultramafic intrusions, South China: A case study from the Gan–Hang tectonic belt.
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Qi, Youqiang, Hu, Ruizhong, Liu, Shen, Coulson, Ian M., Qi, Huawen, Tian, Jianji, and Zhu, Jingjing
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PETROGENESIS , *GEODYNAMICS , *CRETACEOUS Period , *IGNEOUS intrusions , *TECTONIC landforms , *PYROXENITE , *PLATE tectonics - Abstract
A study using whole-rock major-trace elements and Sr–Nd isotopes as well as zircon U–Pb dating has been carried out on Early Cretaceous mafic–ultramafic intrusions from the Gan–Hang tectonic belt (GHTB), South China, to understand the origin of mantle sources and the sequential evolution of the underlying Late Mesozoic lithospheric mantle of this area. The study focused on two intrusions, one at Quzhou and the other at Longyou (see Fig. 1 ). They are primarily composed of mafic–ultramafic rocks with wide range of chemical compositions. The Quzhou mafic rocks have relatively narrow ranges of SiO 2 (48.94–51.79 wt%), MgO (6.07–7.21 wt%), Fe 2 O 3 (10.48–11.56 wt%), CaO (8.20–8.81 wt%), and Mg # (51.7–56.5) with relatively low K 2 O (0.56–0.67 wt%) and Na 2 O (3.09–3.42 wt%). By contrast, the ultramafic rocks from Longyou have distinct lower SiO 2 (41.50–45.11 wt%) and higher MgO (9.05–9.90 wt%), Fe 2 O 3 (12.14–12.62 wt%), CaO (8.64–10.67 wt%), and Mg # (59.5–61.1) with relatively higher K 2 O (1.32–1.75 wt%) and Na 2 O (4.53–5.08 wt%). They are characterized by Ocean Island Basalts (OIB)-type trace element distribution patterns, with a significant enrichment of light rare earth elements (LREE), large ion lithophile elements (LILE, i.e., Rb, Ba, K, and Sr) and high field strength elements (HFSE, i.e., Nb, Ta), and slight depletion of Th, U, Ti, and Y. The intrusions exhibit relatively depleted Sr–Nd isotope compositions, with ( 87 Sr/ 86 Sr) i range of 0.7035 to 0.7055 ( 143 Nd/ 144 Nd) i of 0.51264 to 0.51281 and ε Nd ( t ) values of + 3.0 to + 6.6. Zircon U–Pb dating of Longyou and Quzhou intrusions yields consistent magma emplacement ages of 129.0 ± 3.9 to 126.2 ± 2.4 Ma, respectively. The dating results are consistent with the peak of extension in Early Cretacerous throughout the Gan–Hang tectonic belt. Their magmas were principally derived from near-solidus partial melting of pyroxenites with different content of silica, and the pyroxenites were resulted from a juvenile SCLM peridotite metasomatized by adakitic and felsic melts under a subducted oceanic crust-lithospheric mantle in Neoproterozoic. During the subduction of the oceanic crust, the juvenile SCLM can be sandwiched by the ancient SCLM above and the pyroxenites below and stored for hundreds of millions of years until Late Mesozoic. Then partial melting of the pyroxenites was triggered during the peak of extension in response to the tectonic reactivation of the GHTB in Early Cretaceous. It is clear that fault reactivation and structural constraints within the GHTB had played an important role in its magmatic evolution. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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5. Age and origin of a Palaeozoic nepheline syenite from northern Shanxi Province, China: U–Pb zircon age and whole-rock geochemical and Sr–Nd isotopic constraints.
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Liu, Shen, Hu, Ruizhong, Gao, Shan, Feng, Caixia, Coulson, IanM., Feng, Guangying, Yang, Yuhong, Qi, Youqiang, Yang, Chaogui, and Tang, Liang
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NEPHELINE syenite , *PALEOZOIC Era , *ZIRCON , *ISOTOPE geology , *PETROGENESIS , *INDUCTIVELY coupled plasma mass spectrometry - Abstract
Geochronological, geochemical, and whole-rock Sr–Nd isotopic analyses were performed on a suite of Palaeozoic nepheline syenites from Zijinshan to characterize their ages and petrogenesis. Laser ablation inductively coupled plasma-mass spectrometry U–Pb zircon analyses yield consistent ages of 525.7 ± 2.8 million years for a sample (HYK01). These intrusive rocks belong to the foid syenite magma series in terms of K2O + Na2O contents (14.3–15.2 wt.%) and to the shoshonitic series based on their high K2O contents (5.42–5.61 wt.%). The nepheline syenites are further characterized by high light rare earth element contents [(La/Yb) N = 29.1–36.1]; show modest negative Eu anomalies (δEu = 0.5–0.6) and positive anomalies in Rb, Th, U, Pb, Zr, and Hf; are depleted in Ba and high field strength elements (P and Ti). In addition, all the nepheline syenites in this study display relatively low radiogenic Sr (87Sr/86Sr) i (0.7042–0.7043) and positive ϵNd (t) (0.7–0.8). These results suggest that the nepheline syenites were derived from depleted continental crust. The parent magmas likely experienced fractional crystallization of plagioclase, Ti-bearing oxides (e.g. rutile, ilmenite, and titanite), apatite, and zircon during ascent, with negligible crustal contamination before final emplacement at a high crustal level. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
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6. U–Pb zircon age, geochemical and Sr–Nd isotopic data as constraints on the petrogenesis and emplacement time of the Precambrian mafic dyke swarms in the North China Craton (NCC)
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Liu, Shen, Hu, Ruizhong, Gao, Shan, Feng, Caixia, Coulson, Ian M., Feng, Guangying, Qi, Youqiang, Yang, Yuhong, Yang, Chaogui, and Tang, Liang
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CRATONS , *PETROGENESIS , *ZIRCON , *ANALYTICAL geochemistry , *DIKES (Geology) , *EARTHQUAKE swarms , *PYROXENE , *HORNBLENDE - Abstract
Abstract: Precambrian mafic dykes in the North China Craton (NCC) consist of dolerite. Geochronological, geochemical, and whole-rock Sr–Nd isotopic analyses were performed on this suite of mafic dykes to characterise their ages and petrogenesis. Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) U–Pb zircon analyses yield consistent ages ranging from 837.9±4.8Ma to 2510±18Ma for seven of the mafic dykes (SHS01, TDG01, LJZ01, LQS02, HB02, WJ01, and DST01) from NCC. Based on these, the mafic dykes can be divided into three groupings: ~2.4–2.5Ga, ~1.8–1.9Ga and 0.8–1.0Ga. The studied dykes belong to the alkaline and sub-alkaline magma series in terms of K2O+Na2O contents (2.6–6.2wt.%), and to the Tholeiitic, calc-alkaline and high-K calc-alkaline series based on their K2O contents (0.1–2.1wt.%). The mafic dykes are further characterised by low and variable light rare earth elements (~2.4–2.5Ga mafic dykes, (La/Yb)N =3.83–10.4; ~1.8–1.9Ga mafic dykes, (La/Yb)N =1.45–2.35); 0.8–1.0Ga mafic dykes, (La/Yb) N =0.66–4.27, show variable Eu anomalies (δEu=0.94–1.35, 0.77–1.21; 0.92–1.28, respectively), positive anomalies in Ba, U, La and Pb, and are depleted in Rb and high field strength elements (Nb, Ta, Ti, and minor Zr and Hf). In addition, the studied mafic dykes all display relatively low radiogenic Sr [(87Sr/86Sr)i =0.6747–0.6921; 0.7017–0.7025; 0.7005–0.7049, respectively for the ~2.4–2.5Ga, ~1.8–1.9Ga and 0.8–1.0Ga mafic dyke groups] and large εNd (t) (13.2–13.5; 10.4–11.8; 6.5–8.5, respectively). These results suggest that all the mafic rocks were derived from a depleted mantle source hybridised by foundered lower crust. The parent mafic magmas likely experienced fractional crystallisation of olivine, pyroxene, hornblende, plagioclase and Fe–Ti oxides (e.g., rutile, ilmenite, titanite, etc.) during dyke ascent, with negligible evidence for crustal contamination prior to emplacement at a high crustal level. [Copyright &y& Elsevier]
- Published
- 2012
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7. U–Pb zircon age, geochemical and Sr–Nd isotopic data as constraints on the petrogenesis and emplacement time of andesites from Gerze, southern Qiangtang Block, northern Tibet
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Liu, Shen, Hu, Ruizhong, Gao, Shan, Feng, Caixia, Coulson, Ian M., Feng, Guangying, Qi, Youqiang, Yang, Yuhong, Yang, Chaogui, and Tang, Liang
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URANIUM-lead dating , *ZIRCON , *GEOCHEMISTRY , *NEODYMIUM , *STRONTIUM isotopes , *PETROGENESIS , *ANDESITE - Abstract
Abstract: Mesozoic post-collisional andesites occur in the Gerze area within the Qiangtang Terrane of northern Tibet, China. Geochronological, geochemical, and whole-rock Sr–Nd isotopic analyses were performed on this suite of volcanic rocks to characterize their petrogenesis. Laser ablation-inductively coupled plasma-mass spectrometry U–Pb zircon analyses yielded consistent ages ranging from 122.4±0.4Ma to 124.4±0.4Ma for two andesite samples (JC01 and GZ01). The andesites belong to the alkaline and sub-alkaline magma series in terms of K2O+Na2O contents (4.7–10wt.%), and belong to the high-K calc-alkaline and calc-alkaline series on the basis of their high K2O contents (1.0–3.3 wt.%). The volcanic rocks are further characterized by the enrichment of light rare earth elements [(La/Yb)N =7.4–11.5] and large-ion lithophile elements (e.g., Rb), slightly negative Eu anomalies (Eu/Eu* =0.79–0.94), and negative anomalies in high field strength elements (e.g., Nb, Ta, and Ti) relative to primitive mantle. The samples show slightly elevated (87Sr/86Sr)i values that range from 0.7049 to 0.7057, and low ε Nd(t) values of −3.4 to 0.7. These results suggest that the rocks were derived from a compositionally heterogeneous mantle source and that their parent magmas are basalt magma. The parent mafic magmas may have undergone fractional crystallization of olivine, pyroxene, hornblende, and to a lesser extent, plagioclase during ascent through the thickened crustal pile, with minor or no crustal contamination, before the finally erupting as andesites. [Copyright &y& Elsevier]
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- 2012
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8. Petrogenesis of Late Mesozoic mafic dykes in the Jiaodong Peninsula, eastern North China Craton and implications for the foundering of lower crust
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Liu, Shen, Hu, Ruizhong, Gao, Shan, Feng, Caixia, Yu, Bobin, Feng, Guangying, Qi, Youqiang, Wang, Tao, and Coulson, Ian M.
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DIKES (Geology) , *PETROGENESIS , *MESOZOIC stratigraphic geology , *CRATONS , *CONTINENTAL crust , *DIABASE , *GEOCHEMISTRY - Abstract
Abstract: Late Mesozoic (122.5–127 Ma) mafic dykes (dolerite-porphyries) in the Beibo gold district, Shandong Province, eastern North China Craton, can be subdivided into two groups (high-K and low-K) based upon K2O content. They are characterised by enrichment in light rare earth element (LREE) and some large ion lithophile elements (LILEs) (e.g., Rb, Ba and Sr), similar concentrations of heavy rare earth elements (HREEs), high (87Sr/86Sr) i ranging from 0.7094 to 0.7101, low ε Nd(t) values from −15.3 to −13.9, 206Pb/204Pb=16.98–17.70, 207Pb/204Pb=15.47–15.55 and 208Pb/204Pb=37.61–37.89. In addition, the high-K dolerite-porphyries are distinguished by negative Eu, Nb, Ta, P anomalies in chondrite-normalised REE and primitive-mantle-normalised trace element diagrams. These features suggest that they were derived from a common, enriched garnet-lherzolite mantle beneath the North China Craton, and that this was metasomatised by multiple enrichment events induced by hybridism of foundering lower crust at mantle depths. The low-K dolerite-porphyries were produced by 10–15% partial melting of the garnet-lherzolite source that had undergone metasomatism by carbonate-rich fluids producing secondary phlogopite and amphibole, whereas the high-K group was derived by relatively low-degree (3–5%) partial melting of a source that had experienced metasomatism by a carbonate-rich fluid with crystallisation of only secondary amphibole. The Pd-subgroup platinum-group element (PPGE) (Rh, Pt and Pd) enrichment and Ir-subgroup platinum-group element (IPGE) (Ir and Ru) depletion of these mafic dykes suggest derivation from an S-unsaturated magma. Geochemical and PGE features indicate that fractionation of olivine, clinopyroxene, hornblende, plagioclase, ilmenite, titanite, apatite, laurite and Os–Ir–Ru alloys was important in the formation of the high-K mafic magma. Additionally, separation of all the above phases with the exception of plagioclase and apatite played an important role in the origin of low-K dolerite-porphyries. Minor crustal contamination also occurred during ascent of these mafic magmas. [Copyright &y& Elsevier]
- Published
- 2009
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9. Zircon U–Pb geochronology and major, trace elemental and Sr–Nd–Pb isotopic geochemistry of mafic dykes in western Shandong Province, east China: Constrains on their petrogenesis and geodynamic significance
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Liu, Shen, Hu, RuiZhong, Gao, Shan, Feng, CaiXia, Qi, Liang, Zhong, Hong, Xiao, Tangfu, Qi, YouQiang, Wang, Tao, and Coulson, Ian M.
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GEOCHEMISTRY , *GEOLOGICAL time scales , *PETROGENESIS , *TRACE elements - Abstract
Abstract: Mesozoic mafic dykes in western Shandong Province (Luxi), SE, the North China Craton (NCC) provide an opportunity to examine the nature of their mantle source and the secular evolution of the Mesozoic lithospheric mantle beneath SE NCC. Chronological, geochemical and Sr–Nd–Pb isotopic analyses were carried out on two selected Mesozoic mafic dykes from Mengyin and Zichuan in western Shandong, respectively. Detailed SHRIMP zircon U–Pb dating yields emplacement ages of 144±2 Ma for the Mengyin mafic dykes and of 143±2 Ma for the Zichuan mafic dykes. Both are enriched in LILE (Rb, Ba, Sr, Pb) and LREE without Eu anomalies, but are depleted in HFSE (Nb, Ta and Ti). The dykes have relatively radiogenic Sr (87Sr/86Sr)i (0.706~0.707) and negative ε Nd(t) (−6.5 to −4.4), but remarkably unradiogenic Pb (206Pb/204Pb=16.99–18.36). Both dykes may have experienced crystal fractionation of olivine and clinopyroxene. The Mengyin mafic dykes are characterised by high MgO (9.66–17.97 wt.%), Mg# (66–74), Cr (809–1208 ppm) and Ni (171–390 ppm), indicative of derivation from mantle-derived melts with minor fractionation. In contrast, the Zichuan mafic dykes have relatively low MgO (3.38–4.14 wt.%), Cr (24–56 ppm) and Ni (14–24 ppm), suggesting that they may have originated from an extremely evolved magma. There is evidence in support of multiple enrichment events induced by hybridism of foundering lower crust at mantle depths. For example, phlogopite, amphibole and rutile metasomatism may have affected the lithospheric mantle beneath Mengyin, whereas phlogopite and carbonatite metasomatism modified the lithospheric mantle below Zichuan. This study sheds light also on the geodynamic significance of the 144–143 Ma mafic dykes, for example, we propose that lithospheric thinning underneath southeastern NCC of eastern China was caused by the removal of the lower lithosphere (mantle and lower crust). [Copyright &y& Elsevier]
- Published
- 2008
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10. Late Mesozoic oxidized magma for porphyry Ag mineralization: A comparative study from mineralized and barren granite porphyries in the Lengshuikeng Ag-(Pb-Zn) deposit, South China.
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Qi, Youqiang, Hu, Ruizhong, Gao, Jianfeng, Leng, Chengbiao, Gong, Haotian, and Gao, Wei
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PORPHYRY , *GRANITE , *MAGMAS , *METALLOGENY , *PLAGIOCLASE , *SIDEROPHILE elements , *RARE earth metals - Abstract
• Two episodes granite porphyry, 156 Ma for ore-forming one, 137 Ma for barren one. • Both derived from dehydration melting of Proterozoic meta-sedimentary rocks. • Relative moderate oxidation state and water content in ore-forming magma. The Lengshuikeng Ag-(Pb-Zn) deposit (LSKD) is one of the largest independent porphyry silver deposits in China. Its silver mineralization is related to the Late Mesozoic granite porphyry, but the oxidizing hydrous conditions of the associated magma are still unclear. This study focuses on the associated granite porphyry (GP) and barren K-feldspar granite porphyry (KFGP) to constrain their oxidizing hydrous conditions. New zircon U-Pb dating shows the GP emplaced at 155.8 ± 1.9 Ma and 158.5 ± 2.3 Ma for GP, and the KFGP emplaced at 136.6 ± 1.9 Ma. Both granites are peraluminous with A/CNK ratios of 1.09–3.01 (mean = 1.48), similar to that of typical S-type granites. They are enriched in light rare earth elements (LREE), with large (La/Yb) N (7.0–19.1 for the GP and 1.8–34.3 for the KFGP) and negative Eu anomalies (0.29–0.67 for the GP and 0.02–0.05 for the KFGP). The GP has ε Nd (t) values ranging from − 10.0 to − 9.7 with T DM2 ages of 1688–1915 Ma, while the KFGP has higher ε Nd (t) values ranging from − 7.5 to − 7.6 with younger T DM2 ages of 1538–1548 Ma. The initial Pb isotopic ratios for (206Pb/204Pb) i , (207Pb/204Pb) i and (208Pb/204Pb) i are 17.647–17.952, 15.555–15.604 and 37.851–38.541, respectively. Our new chemical and isotopic data suggest that both granites were dominantly derived from dehydration melting of the Proterozoic meta-sedimentary rocks, with more dehydration fluids for the GP and relatively more mantle contribution to the KFGP. Both granites underwent fractional crystallization of plagioclase, K-feldspar and ilmenite/magnetite followed by minor assimilation of the upper crust. Comparative study on the relative water content, oxidation state and melting temperature of magma have shown relatively moderate oxidation state and water content in the associated magma probably played more important roles in porphyry silver mineralization than other factors in porphyry Cu deposit. This study helps deepen the understanding of silver mineralization. [ABSTRACT FROM AUTHOR]
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- 2020
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11. Geochronological and geochemical constraints on the petrogenesis of alkaline ultramafic dykes from southwest Guizhou Province, SW China
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Liu, Shen, Su, Wenchao, Hu, Ruizhong, Feng, Caixia, Gao, Shan, Coulson, Ian M., Wang, Tao, Feng, Guangying, Tao, Yan, and Xia, Yong
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GEOLOGICAL time scales , *GEOCHEMISTRY , *PETROGENESIS , *DIKES (Geology) , *STRONTIUM isotopes , *NEODYMIUM - Abstract
Abstract: Geochronological, geochemical and whole-rock Sr–Nd isotopic analyses have been completed on a suite of alkaline ultramafic dykes from southwest (SW) Guizhou Province, China with the aim of characterising their petrogenesis. The Baiceng ultramafic dykes have a LA-ICP-MS zircon 206Pb/238U age of 88.1±1.1Ma (n =8), whereas two phlogopites studied by 40Ar/39Ar dating methods give emplacement ages of 85.25±0.57Ma and 87.51±0.45Ma for ultramafic dykes from Yinhe and Lurong, respectively. In terms of composition, these Late Mesozoic ultramafic dykes belong to the alkaline magma series due to their high K2O (3.31–5.04wt.%) contents. The dykes are characterised by enrichment of light rare earth element (LREE) and large-ion lithosphile elements (LILEs) (Rb and Ba), negative anomalies in high field strength elements (HFSEs), such as, Nb, Ta and Ti relative to primitive mantle, low initial 87Sr/86Sr ratios (0.7060–0.7063) and positive ε Nd(t) values (0.3–0.4). Such features suggest derivation from low degree (<1%) partial melting of depleted asthenospheric mantle (garnet-lherzolite), and contamination to various degrees (∼10%) by interaction with upper crustal materials. [Copyright &y& Elsevier]
- Published
- 2010
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12. Geochronology, petrogenesis and tectonic significance of the Jitang granitic pluton in eastern Tibet, SW China.
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Tao, Yan, Bi, Xianwu, Li, Chusi, Hu, Ruizhong, Li, Yubang, and Liao, Mingyang
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PETROGENESIS , *GEOLOGICAL time scales , *STRUCTURAL geology , *GRANITE , *METAMORPHISM (Geology) - Abstract
Abstract: The Jitang granitic pluton, which is situated in the southern margin of the North Qiangtang block in eastern Tibet, may provide critical information about the source and derivation of the North Qiangtang block during Gondwana breakup and dispersion. In this paper we report relevant data such as zircon U–Pb age, whole-rock major and trace element abundances, and Sr–Nd isotopes for the Jitang pluton. The major rock types of the pluton are granodiorite and biotite granite. Whole-rock major element data reveal that the Jitang pluton is a peraluminous S-type granitic pluton. The U–Pb age of zircons from the pluton is 219.1±1.7Ma, which is ~10Ma younger than the age of high-pressure metamorphism in the Longmu Co–Shuanghu collisional suture between the North and South Qiangtang blocks. The Jitang granitoids show pronounced negative Ba–Eu–Sr anomalies, high initial 87Sr/86Sr ratios from 0.7266 to 0.7389 and low ε Nd(t) values for from −11.1 to −13.2, which are remarkably similar to the gneisses and meta-sedimentary rocks from the Indian craton as well as the North Qiangtang block. The results from this study indicate that the Jitang granitoids formed by melts derived from a crustal source with Sr–Nd isotopic compositions similar to those of the Indian cratonic crust. We concur with the previous interpretation based on detrital zircon records that the North Qiangtang block was derived from the Indian Gondwana. [Copyright &y& Elsevier]
- Published
- 2014
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13. Geochemical, Sr–Nd isotopic, and zircon U–Pb geochronological constraints on the petrogenesis of Late Paleoproterozoic mafic dykes within the northern North China Craton, Shanxi Province, China.
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Liu, Shen, Feng, Caixia, Jahn, Bor-ming, Hu, Ruizhong, Gao, Shan, Feng, Guangying, Lai, Shaocong, Yang, Yuhong, Qi, Youqiang, and Coulson, Ian M.
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GEOCHEMISTRY , *NEODYMIUM isotopes , *ZIRCON , *URANIUM-lead dating , *GEOLOGICAL time scales , *PETROGENESIS - Abstract
Highlights: [•] Late Paleoproterozoic mafic dykes in the North China Craton were dated at ∼1620Ma. [•] The dykes were derived from depleted mantle source. [•] The origin of the dykes is related to the foundered lower crustal. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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14. Zircon U–Pb age, geochemical, and Sr–Nd–Hf isotopic constraints on the origin of mafic dykes in the Shaanxi Province, North China Craton, China.
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Liu, Shen, Feng, Caixia, Jahn, Bor-ming, Hu, Ruizhong, Gao, Shan, Coulson, Ian M., Feng, Guangying, Lai, Shaocong, Yang, Chaogui, and Yang, Yuhong
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ZIRCON , *RADIOACTIVE dating , *GEOCHEMISTRY , *MAFIC rocks , *DIABASE , *DIKES (Geology) - Abstract
Mafic dolerite dykes form a series of swarms that are widespread across the North China Craton (NCC). We present U–Pb zircon ages, geochemical data, and Sr–Nd–Hf isotopic data for representative samples of the Shaanxi dolerite dykes in the southern NCC. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb zircon analyses for three samples yield ages ranging from 448.1±1.2 to 489.6±0.9Ma (i.e., Cambro-Ordovician). The dolerites are characterised by a wide range of rock compositions. They display enrichments in light rare earth element (LREEs) and large ion lithophile element (LILE) (i.e., Ba, U, K and Pb), as well as depletion in high field strength (HFSE) (Nb, Ta, Hf and Ti). The mafic dykes have relatively uniform (87Sr/86Sr) i ranging from 0.7049 to 0.7076, (176Hf/177Hf) i from 0.282187 to 0.282236, low εNd (t) values, from −4.1 to −4.9, εHf (t) values of between −7.9 and −9.8, for zircon, and high hafnium model ages (TDM1 =1366–1535Ma, TDM2 =1924–2081Ma). These results suggest that the dykes are derived by partial melting of an enriched, lithospheric mantle source. The magmas underwent fractionation of olivine, pyroxene, plagioclase, and Ti-bearing phases (rutile, ilmenite, titanite), along with crustal contamination. The formation of the Shaanxi Province, NCC mafic dykes can be attributed to the collision between the NCC and south Qinling Block. Specifically, these magmas formed as a result of crustal thinning in response to extension that followed this collision. [ABSTRACT FROM AUTHOR]
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- 2013
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15. Petrogenesis and metallogenic implications of volcanic rocks from the Lawu basin, eastern Tibet: Insights into the intracontinental Eocene-Oligocene porphyry copper systems.
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Xu, Yue, Xu, Leiluo, Bi, Xianwu, Hu, Ruizhong, Chen, Xilian, Ma, Rui, Zhu, Jingjing, Yu, Hongjun, Liu, Baohua, and Li, Juan
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VOLCANIC ash, tuff, etc. , *PORPHYRY , *RARE earth metals , *EOCENE Epoch , *LAVA , *PETROGENESIS , *MARINE sediments - Abstract
• The Lawu volcanic rocks and associated porphyries have a closely comagmatic relation. • The mantle domains were metasomatized by Paleo-Tethyan oceanic marine sediments. • The porphyry-volcanic system has similar H 2 O but lower fO 2 of than Yulong deposit. Generally, porphyry Cu deposits are associated with the comagmatic porphyry (or subvolcanic)-volcanic systems of high magmatic H 2 O-fO 2 conditions. The volcanic rocks, as the counterpart of the porphyries, thus can provide some significant insights into the fertility of the porphyries to some extent. For this reason, we have used the Lawu volcanic rocks and spatial-temporal closely-related porphyries in the newly discovered porphyry Cu prospects (e.g., Seli, Zongguo, Mamupu) in the southern segment of the Yulong intracontinental porphyry Cu belt to illustrate the relationship between the porphyries and volcanic rocks, petrogenesis of the volcanic rocks, and then to evaluate the ore potential of the porphyries based on the magmatic H 2 O-fO 2 conditions. Both the Lawu volcanic rocks and Seli-Zonguo-Mamupu porphyries are shoshonitic and metaluminous, and have similar REE patterns, and Sr-Nd-Hf isotopic compositions, which suggest a comagmatic relation between the volcanic rocks and porphyries. An episodic magmatism model is proposed to explain the slightly younger age (~36–35 Ma) and less evolved nature of volcanic rocks than the porphyries. The Lawu volcanic rocks of mainly intermediate composition (SiO 2 = 54.25–64.68 wt%) have high K 2 O (4.75–5.94 wt%) and high K 2 O/Na 2 O ratios (1.69–2.00), broadly similar to the coeval Yulong fertile granitic porphyries and the Nangqian mafic lavas. The (87Sr/86Sr) i and ε Nd (t) values, uniform zircon ε Hf (t) and δ18O values, and lack of inherited zircons of the Lawu volcanic rocks don't support their formation by mixing between the mantle-derived Nangqian mafic lavas and crust-derived Yulong felsic porphyries or assimilation and fractional crystallization (AFC) of mafic magmas. They are characterized by high Ba/Th, Ba/La and listric-shaped normalized rare earth element profile with significantly negative Nb-Ta-Ti anomalies, and have high initial 87Sr/86Sr ratios (0.7071–0.7079) and low ε Nd (t) values (−5.71 to −3.05), and low zircon ε Hf (t) (−1.53 to 4.09) and clearly high δ18O values (6.67–8.42‰), suggesting that, they were probably formed by fractional crystallization (FC) of mantle-derived mafic magmas and originated from mantle domains modified by significant amount of H 2 O-rich marine sediments of the Paleo-Tethyan oceanic slab. Magmatic H 2 O contents calculated from deepest-crystallized amphiboles indicate that, the Lawu volcanic rocks and Zongguo porphyries have initial magmatic H 2 O contents as high as the Yulong fertile porphyries and typical porphyry Cu systems worldwide (commonly >4 wt% H 2 O). Magmatic fO 2 (ΔFMQ) of the Lawu volcanic rocks (0.6–1.3, ave. 0.9 ± 0.1) and the Zongguo porphyries (0.9–1.7, ave. 1.4 ± 0.2) are clearly lower than the fertile porphyries in the giant Yulong deposit (ΔFMQ = 1.6–3.3, ave. 2.3 ± 0.5) and typical porphyry Cu deposits in the world (commonly ΔFMQ > 2). The slightly lower magmatic H 2 O contents and slightly higher magmatic fO 2 of the Zongguo porphyries than the Lawu volcanic rocks were ascribed to variable degassing during magmatic evolution. These suggest that, in spite of the high magmatic H 2 O contents, the comagmatic porphyries (at least the Zongguo porphyries) of the Lawu volcanic rocks in the southern segment of the Yulong porphyry Cu belt are unlikely to produce large-scale porphyry Cu mineralization like the giant Yulong deposit, due to the low magmatic fO 2 conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
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