The Hua’aobaote Pb-Zn-Ag Polymetallic orefield is situated in the southern section of the Great Xing’an Range(GXAR),which has experienced extensive magmatism.Since the Paleozoic,there are two stages of magmatism in ...The Hua’aobaote Pb-Zn-Ag Polymetallic orefield is situated in the southern section of the Great Xing’an Range(GXAR),which has experienced extensive magmatism.Since the Paleozoic,there are two stages of magmatism in Hua’aobaote orefield occurred in the Paleozoic and Mesozoic.The Mesozoic magmatism is of great significance for the PbZn-Ag Polymetallic mineralization in Hua’aobaote orefield.In this study,new geochemical data was obtained to discuss the timing and petrogenesis of the magmatic rocks and its geodynamic and metallogenic significance.Zircon U-Pb ages reveal that the felsic igneous rocks from the Hua’aobaote orefield were formed in the Early Permian(294.8±3.2 Ma)and Early Cretaceous(132.6±1.4 Ma).Geochemically,the Early Permian granodiorite porphyrite is characterized by high Sr/Y(42-63)ratios and Mg^(#)(62.24-70.74)values and low heavy rare earth element(HREE)(5.09-6.79 ppm)contents.The granodiorite porphyrite is also characterized by depleted Sr-Nd initial isotopic signatures[ε_(Nd)(t)=5.91-7.59,(^(87)Sr/^(86)Sr)i=0.7029-0.7030],exhibiting adakitic characteristics.The Early Cretaceous granite porphyry and rhyolite are A-type felsic igneous rocks,and demonstrate high SiO_(2),Na_(2)O+K_(2)O and rare earth element(REE)contents,low CaO and MgO contents,low(^(87)Sr/^(86)Sr)i ratios(0.7044-0.7058),and positive ε_(Nd)(t)values(2.57-4.65).Whole-rock Pb isotopic compositions in granodiorite porphyrite are:206Pb/204Pb=17.631-18.149,^(207)Pb/^(204)Pb=15.422-15.450,and ^(208)Pb/^(204)Pb=37.325-37.729.The granite porphyry and rhyolite have initial ^(206)Pb/^(204)Pb,^(207)Pb/^(204)Pb,and ^(208)Pb/^(204)Pb ratios of 18.106-19.309,15.489-15.539,and 37.821-38.05,respectively.Sr-Nd-Pb isotopic evidence suggests that the Early Permian granodiorite porphyrite is likely to derive from slab melts and modified by peridotitic mantle wedge in the subduction tectonic setting of the Paleo-Asian Ocean.The Early Cretaceous A-type felsic igneous rocks were derived from juvenile lower crust,accompanied by limited crustal contamination and various degree of fractional crystallisation during magma emplacement.The Early Cretaceous magmatism and related mineralization were formed in a post-orogenic tectonic setting that attributed to the closure of the Mongol-Okhotsk Ocean.Pb isotopic data for the various rock units in the study area indicate that the Mesozoic magma source contributed substantial Pb,Zn,and Ag to the Hua’aobaote deposit.展开更多
Rare metal ore reserves are an important strategic resource, and their metallogenic mechanism and mineralization studies have also been received widespread international attention.
Larch caterpillars are widely distributed in the Great Xing’an boreal forests;however,the relationship between caterpillar defoliation dynamics and climatic factors is poorly understood.The aims of this study are to ...Larch caterpillars are widely distributed in the Great Xing’an boreal forests;however,the relationship between caterpillar defoliation dynamics and climatic factors is poorly understood.The aims of this study are to investigate the primary weather conditions that might influence forest defoliation and to identify the most important life stage of the larch caterpillar at which forest defoliation might be mitigated by incorporating more inhibitory influences from climatic factors.The life cycle of the larch caterpillar was partitioned into four stages and multiple linear regression and mixed effect models were combined with a relative weight analysis approach to evaluate the importance and influence of meteorological variables on defoliation dynamics.The results show that warmer temperatures in growing seasons and overwintering periods can increase the defoliation area,while rainy and humid growing seasons decrease the defoliation area.Total precipitation during the early instar larval period had the greatest power to explain the variance in defoliation dynamics and had a very strong inhibitory effect,followed by the accumulative temperatures of the late instar larval period which had a positive impact,and precipitation during the middle instar larval period which had a negative impact.Weather conditions during the early instar larval period had the greatest influence on the area defoliated and accounted for 40%of the explained variance.This study demonstrates that climatic warming and drying will increase the risk of larch caterpillar outbreaks in the Great Xing’an Mountains.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.41972312,41672329)the National Key Research and Development Project of China(Grant No.2016YFC0600509)the Project of China Geological Survey(Grant No.1212011120341)。
文摘The Hua’aobaote Pb-Zn-Ag Polymetallic orefield is situated in the southern section of the Great Xing’an Range(GXAR),which has experienced extensive magmatism.Since the Paleozoic,there are two stages of magmatism in Hua’aobaote orefield occurred in the Paleozoic and Mesozoic.The Mesozoic magmatism is of great significance for the PbZn-Ag Polymetallic mineralization in Hua’aobaote orefield.In this study,new geochemical data was obtained to discuss the timing and petrogenesis of the magmatic rocks and its geodynamic and metallogenic significance.Zircon U-Pb ages reveal that the felsic igneous rocks from the Hua’aobaote orefield were formed in the Early Permian(294.8±3.2 Ma)and Early Cretaceous(132.6±1.4 Ma).Geochemically,the Early Permian granodiorite porphyrite is characterized by high Sr/Y(42-63)ratios and Mg^(#)(62.24-70.74)values and low heavy rare earth element(HREE)(5.09-6.79 ppm)contents.The granodiorite porphyrite is also characterized by depleted Sr-Nd initial isotopic signatures[ε_(Nd)(t)=5.91-7.59,(^(87)Sr/^(86)Sr)i=0.7029-0.7030],exhibiting adakitic characteristics.The Early Cretaceous granite porphyry and rhyolite are A-type felsic igneous rocks,and demonstrate high SiO_(2),Na_(2)O+K_(2)O and rare earth element(REE)contents,low CaO and MgO contents,low(^(87)Sr/^(86)Sr)i ratios(0.7044-0.7058),and positive ε_(Nd)(t)values(2.57-4.65).Whole-rock Pb isotopic compositions in granodiorite porphyrite are:206Pb/204Pb=17.631-18.149,^(207)Pb/^(204)Pb=15.422-15.450,and ^(208)Pb/^(204)Pb=37.325-37.729.The granite porphyry and rhyolite have initial ^(206)Pb/^(204)Pb,^(207)Pb/^(204)Pb,and ^(208)Pb/^(204)Pb ratios of 18.106-19.309,15.489-15.539,and 37.821-38.05,respectively.Sr-Nd-Pb isotopic evidence suggests that the Early Permian granodiorite porphyrite is likely to derive from slab melts and modified by peridotitic mantle wedge in the subduction tectonic setting of the Paleo-Asian Ocean.The Early Cretaceous A-type felsic igneous rocks were derived from juvenile lower crust,accompanied by limited crustal contamination and various degree of fractional crystallisation during magma emplacement.The Early Cretaceous magmatism and related mineralization were formed in a post-orogenic tectonic setting that attributed to the closure of the Mongol-Okhotsk Ocean.Pb isotopic data for the various rock units in the study area indicate that the Mesozoic magma source contributed substantial Pb,Zn,and Ag to the Hua’aobaote deposit.
基金financially supported by the National Natural Science Foundation of China(grant No.41302061)
文摘Rare metal ore reserves are an important strategic resource, and their metallogenic mechanism and mineralization studies have also been received widespread international attention.
基金The work was supported by the National Key R&D Program of China(2017YFA0604403).
文摘Larch caterpillars are widely distributed in the Great Xing’an boreal forests;however,the relationship between caterpillar defoliation dynamics and climatic factors is poorly understood.The aims of this study are to investigate the primary weather conditions that might influence forest defoliation and to identify the most important life stage of the larch caterpillar at which forest defoliation might be mitigated by incorporating more inhibitory influences from climatic factors.The life cycle of the larch caterpillar was partitioned into four stages and multiple linear regression and mixed effect models were combined with a relative weight analysis approach to evaluate the importance and influence of meteorological variables on defoliation dynamics.The results show that warmer temperatures in growing seasons and overwintering periods can increase the defoliation area,while rainy and humid growing seasons decrease the defoliation area.Total precipitation during the early instar larval period had the greatest power to explain the variance in defoliation dynamics and had a very strong inhibitory effect,followed by the accumulative temperatures of the late instar larval period which had a positive impact,and precipitation during the middle instar larval period which had a negative impact.Weather conditions during the early instar larval period had the greatest influence on the area defoliated and accounted for 40%of the explained variance.This study demonstrates that climatic warming and drying will increase the risk of larch caterpillar outbreaks in the Great Xing’an Mountains.
