Succession Accumulating And Discussion On Structural Properties In Manitu Formation During Late Jurassic Period In The Area Of Hao Rao Mountain,Great Hinggan Range

Manitu Formation during Late Jurassic period in the area of Hao rao Mountain，Great Xing’an Range，is dominated by a set of neutral volcano rock and a smallamount of neutral volcanic clastic.Comebined with field investigation and zirconU-Pb isotopic dating results on Manitu Formation of Hao rao Mountain of GreatHinggan Range during Late Jurassic period，this paper systematically studied thecombination of lithology and the timing evidence，and discussed the structuralproperties of its formation.Investigation implications:1、Systematically defined the succession characteristicsof Manitu Formation of Hao rao Mountain in Great Hinggan Range during LateJurassic period.From the vertically combination of Manitu Formation，the lower partmainly composed of overflow lava，the upper part is volcanic breccias of the airfallfacies and the top is the prase of the outbreaking volcanic agglomerated rock.Thecomposition of each lithofacies contribute to different eruption rhythm.The volcaniccycle generally consists of a plurality of rhythm.Single rhythm is mainly composedof neutral volcanic rocks of airfall facies，they are trachyandesite，andesite，and theupper part turns to the andesitic breccias tuff.These rocks including andesite，trachyte，and the upper part mostly consist of andesitic tuff，andesite(containing)breccia tuff，and andesitic agglomerate rocks.2、The zircon U-Pb isotopic dating techniquescontribute to the chronological framework of Manitu Formation of Hao rao Mountainin Great Hinggan Range during Late Jurassic period.According to age of the lowerand upper covering rocks，the paper concluded that the Manitu Formation rocksformed during135~145Ma the late Jurassic period.3、Manitu Formation rocksspreads a little in the study area and they exposed a zonal feature.They considered tobe a fissure eruption of volcanic types.4、Manitu Formation volcanic rocks have thefeature of saturated SiO2and its petrology type drop into the calcium-alkalineseries.They have a high potassium component.The rare earch elements curve liningto the right to show LREE enrichment，HREE characteristic loss，and weakly δEunegative anomalies，plagioclase fractional crystallization of minerals is not obvious，thus they possibly comagmatic evolution form.5、Manitu Formation volcanic rocks of Hao rao Mountain formed in the extensional tectonic environment with the Okhotck’sclosure，and were less influenced by the subduction of the Pacific plate.