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地球学报  1991 

GEOCHEMICAL CHARACTER AND ORIGIN OF CUMULATES OF THE HONGGULELENG OPHIOLITE, XINJIANG, CHINA
新疆洪古勒楞蛇绿岩套中堆积杂岩的地球化学特征及成因

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Abstract:

The cumulative complex is well preserved in the Hongguleleng ophiolitic suite located in the Hebukesai County, Xinjiang. The complex is consisted of the following sequences from bottom to top: 1) assemblage of plagioclase dunite and plagioclase harzburgite in iuterlayering, 2) metatroctolitic and leucotroctolitic interlayers as a rhythmic stratified structure,3)olivine gabbro and then homogeneous gabbro layer. The basic lava (diabase) layer is overlaid on the homogeneous gabbro layer. The andisitic basalt layer overlying on the ophiolitic suite may be cogenetic.The cumulative complex is typical of PTO assemblage and is characterized by an Al-rich evolution trend. The chemical compositions of the cumulates from the bottom to top have a tendenoy to increase in the CaO, Al2O3, SiO2, TiO2, Na2O, K2O, B and Sr, and decrease in the MgO, FeO, Cr, Co, and Ni. The chemical variations of major, trace and rare earth elements for the cumulates show the systematic change similar to those of the lavered mafic and ultramafic intrusions.In this paper, the authers suggest that the cumulative sequences are formed by liquid or magma accumulation and explain the mechanism of the liquid accumulation origin.

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