Early Mesozoic Igneous Petrotecttonic Assemblages And Tectonic Evolution Of Eastern Hailongjiang Provinces

The eastern Heilongjiang is located in two tectonic zone of Palao—Asian tectonic domain and Circum—Pacific Mesozoic tectonic domain, during which the separation, and matching of microplate is very complex. Therefore, illustrate the Earth dynamics process and the time reversal of the two tectonic domain as well as the micro tectonic plate's activity have the very vital significance with tectonic association research of igneous rock as the master line.Under project subsidization of the China Geological Survey, A mineralogical, petrologic, petrochemical, geochemistrical, and chronological study has been carried out on the Paleo—Mesozoic igneous rock in this paper, the geotectonic evolutionary regulation on the study area in the early Mesozoic has been discussed.The eastern Heilongjiang Paleo—Mesozoic igneous rock centralism distributes in the NNE belt-shaped Yichun-Yanshou magmatic-structural belt and NE belt-shaped Raohe-Laoheishan magmatic-structural belt, Between both are the Jiamusi uplift zone, only a small number of sporadic exposed Paleo—Mesozoic igneous rock.The Yichun-Yanshou magmatic-structural belt ,with the age of igneous rock diagenesis 202～234 Ma, constitutes NNE magmatic-structural belt in the space ,mainly composed of the initial orogenic gabbro - diorite association, the peak orogenic granodiorite -granite association, the late orogenic sye-nogranite association, post—orogenic A-type granite-peralkaline granite association. This orogenetic process is a series of completed tectonic evolution, reflecting the initial orogenic magma underplating and magma mixing, the peak orogenic strong interaction between the crust and mantle (magma mixing), the late orogenic lithosphere started to delaminate and the post—orogenic extensional tectonic setting. The intrusive rocks' emplacement mechanism is mainly the dyke explictite in the Yichun-Yanshou magmatic-structural belt .The Yichun-Yanshou magmatic-structural belt, under the circum—Pacific tectonic mechanism, is the product of the again matching and orogensis of the Songnei - Zhang Guangcai block and Jiamusi block ,concurrently constrainted by double tectonic setting constraints of Pacific plate separate and the again matching and orogensis of the Songnei - Zhang Guangcai block and Jiamusi block.The Paleo—Mesozoic Raohe-Laoheishan magmatic-structural belt, located between both the Jiamusi block Nadanhada terrain, mainly composed of the bimodal ultrabasic rocks-rhyolite association, of ultramafic-mafic rock-pillow lava association, of magmatic arc association, of syn—orogenic granodiorite - granite association, with the age of diagenesis 156.2～205.3Ma. And the late Triassic bimodal association reflects the characteristics of intracontinental rift setting, the early Jurassic Raohe ultramafic - mafic rock - pillow lava association represent the environmental characteristics of oceanic island, magmatic arc association represent the characteristics of island arc and active continental margin with the background of the plate subduction, middle Jurassic syn-orogenic granodiorite-granite association reflects characteristics of matching and orogensis after continental accretion. They generally represent a split from passive margin to active continental margin and eventually transformed into a continental - margin accretionary wedge with a matching and orogensis process of evolution, which is accompanied by a passive margin deep-sea sediment basin, active continental margin back-arc foreland basin sediments and continental molasse formation.