The Hashitu molybdenum deposit is located in the southern part of the Great Hinggan Range, NE China. Molybdenum mineralization is hosted by and genetically associated with monzogranite and porphyritic syenogranite. Sr...The Hashitu molybdenum deposit is located in the southern part of the Great Hinggan Range, NE China. Molybdenum mineralization is hosted by and genetically associated with monzogranite and porphyritic syenogranite. Sr-Nd-Pb isotopes of the intrusions show that the porphyritic syenogranite has initial ^87Sr/^86Sr ratios of 0.70418-0.70952, ENd（t） values of 1.3 to 2.1 （t=143 Ma）, ^206Pb/^204Pb ratios of 19.191-19.573, ^207Tpb/^204pb ratios of 15.551-15.572, and ^208Pb/^204Pb ratios of 38.826-39.143. The monzogranite has initial 87Sr/86Sr ratios of 0.70293-0.71305, εNd（t） values of 1.1 to 2.0 （t=-147 Ma）, ^206Pb/^204pb ratios of 19.507-20.075, ^207Pb/^204Pb ratios of 15.564-15.596, and ^208Pb/^204Pb ratios of 39.012-39.599. The calculated Nd model ages （TDM） for monzogranite and porphyritic syenogranite range from 866 to 1121 Ma and 795 to 1020 Ma, respectively. The granitic rocks in the Hashitu area have the same isotope range as granites in the southern parts of the Great Hinggan Range. The isotope composition indicates that these granites are derived from the partial melting of a juvenile lower crust originating from a depleted mantle with minor contamination by ancient continental crust. The integrating our results with published data and the Late Mesozoic regional tectonic setting of the region suggest that the granites in the Hashitu area formed in an intra-continent extensional setting, and they are related to the thinning of the thickened lithosphere and upwelling of the asthenosphere.展开更多
Mantle branch structure is the third tectonic unit of multiple evolution of a mantle branch. It is not only the main mechanism of intercontinental orogeny, but also an important ore-forming and ore-control structure. ...Mantle branch structure is the third tectonic unit of multiple evolution of a mantle branch. It is not only the main mechanism of intercontinental orogeny, but also an important ore-forming and ore-control structure. Studies on geotectonic evolution, regional geological characteristics and oreforming and ore-control structures have shown that since the Mesozoic the Da Hinggan Mts. region has entered a typical intercontinental orogenic stage, and it is closely related to mantle branch activities. The south-central segment of the Da Hinggan Mts. is a typical mantle branch structure and possesses obvious magmatic-metamorphic complexes in the core, detachment slip beds in the periphery and overlapped fault depression basins. Moreover, all of these are the principal factors leading to ore formation and ore control in the region. This paper also further explores the mechanism of mineralization in the south-central segment of the Da Hinggan, summaries the rules of mineralization, puts forward the models of mineralization and points out future ore-exploring orientation.展开更多
基金part of the ongoing project "Superimposed tectonic activities and large-scale oreforming processes of the Hinggan-Mongolia Orogenic Belt"financially supported by the State Basic Research Program of China(2013CB429805)
文摘The Hashitu molybdenum deposit is located in the southern part of the Great Hinggan Range, NE China. Molybdenum mineralization is hosted by and genetically associated with monzogranite and porphyritic syenogranite. Sr-Nd-Pb isotopes of the intrusions show that the porphyritic syenogranite has initial ^87Sr/^86Sr ratios of 0.70418-0.70952, ENd（t） values of 1.3 to 2.1 （t=143 Ma）, ^206Pb/^204Pb ratios of 19.191-19.573, ^207Tpb/^204pb ratios of 15.551-15.572, and ^208Pb/^204Pb ratios of 38.826-39.143. The monzogranite has initial 87Sr/86Sr ratios of 0.70293-0.71305, εNd（t） values of 1.1 to 2.0 （t=-147 Ma）, ^206Pb/^204pb ratios of 19.507-20.075, ^207Pb/^204Pb ratios of 15.564-15.596, and ^208Pb/^204Pb ratios of 39.012-39.599. The calculated Nd model ages （TDM） for monzogranite and porphyritic syenogranite range from 866 to 1121 Ma and 795 to 1020 Ma, respectively. The granitic rocks in the Hashitu area have the same isotope range as granites in the southern parts of the Great Hinggan Range. The isotope composition indicates that these granites are derived from the partial melting of a juvenile lower crust originating from a depleted mantle with minor contamination by ancient continental crust. The integrating our results with published data and the Late Mesozoic regional tectonic setting of the region suggest that the granites in the Hashitu area formed in an intra-continent extensional setting, and they are related to the thinning of the thickened lithosphere and upwelling of the asthenosphere.
基金co-supported by the National Natural Science Foundation Project (No.40872137,40372103)Crisis Mines Study Project (No.20089948)Inner Mongolia Geological Exploring Important Project (No.2004-05)
文摘Mantle branch structure is the third tectonic unit of multiple evolution of a mantle branch. It is not only the main mechanism of intercontinental orogeny, but also an important ore-forming and ore-control structure. Studies on geotectonic evolution, regional geological characteristics and oreforming and ore-control structures have shown that since the Mesozoic the Da Hinggan Mts. region has entered a typical intercontinental orogenic stage, and it is closely related to mantle branch activities. The south-central segment of the Da Hinggan Mts. is a typical mantle branch structure and possesses obvious magmatic-metamorphic complexes in the core, detachment slip beds in the periphery and overlapped fault depression basins. Moreover, all of these are the principal factors leading to ore formation and ore control in the region. This paper also further explores the mechanism of mineralization in the south-central segment of the Da Hinggan, summaries the rules of mineralization, puts forward the models of mineralization and points out future ore-exploring orientation.
