The Petrological And Geochemical Characteristive Of Ophiolite On The Area Of Diyanmiao In The Inner Mongolia

Diyanmiao ophiolite occurs in Xing’anling-Mongolian Orogenic Belt between theSino-Korean paleoplate and the Siberian paleoplate in the central sector of Inner Mongolia.According to field geological investigation and laboratory study, we found Diyanmiaoophiolite, nearly in NNE-NE direction, that can be divided into two zones: the south,Baiyinbulage ophiolite zone, which is mainly composed of gabbro and the north,Naolaiketuophiolite zone, which is predominantly composed of basalt. Each of them is about3kmwide,30km long,and Diyanmiao ophiolite outcrops completely,including serpentined harz-burgite, beded-massive gabbro,anorthosite,spilite,pillow basalt, keratophyre, baschtauite,and chert from bottom to top.Diyanmiao ophiolite lithology are typical of each units. The chondrite-normalizedREE patterns of augite peridotite represent a typical mantle section of the SSZ-typeophiolite. Pillow basalt has the island-arc tholeiite （IAT） features. The values of Al₂O₃/（Al₂O₃+Fe₂O₃） of chert display the characteristics of continental margin. The traceelements reveals a deficit of HFSEs （Nb, Ta） and enrichment of LILEs, the incompatibilityand the non-conservative elements, same as the typical ophiolite characteristics associatedwith subduction zones.Through the gabbro sample isotopic dating, averages380Ma, the Diyanmiao ophiolitewas formed in middle devonian; According to the geological and geochemical characteris-tics of the Diyanmiao ophiolite, it belongs to the volcanic-arc （VA） type,which related tosubduction.It has differentiation characteristics of a monocyclic and closed system in asmall magma chamber, its scale of oceanization is relatively small,and it is in a rapid openand close environment.Diyanmiao ophiolite exist the massive sulfide deposit and Ni,Cr,Co,Cu mineralizationassociated with the ophiolite, It will benefits the the prospecting andassessments of Ni,Cr,Co,Cu.