摘要
本文将西准噶尔地区蛇绿岩分为两类:一类是变质橄榄岩+橄长岩+辉长岩岩石组合(简称PTG系列);另一类则是变质橄榄岩+辉石岩+辉长岩岩石组合(简称PPG系列)。前者以达拉布特、和布克赛尔蛇绿岩带为代表,后者以唐巴勒、玛依勒山蛇绿岩带为代表。PTG系列遵循富Al的演化趋势,而PPG系列则遵循富Ca的演化趋势;从而造成两类蛇绿岩之间在岩石组合、矿物学、岩石化学、稀土元素等地球化学以及所含铬铁矿床的种属上均有明显的差异。 两类蛇绿岩中变质橄榄岩的成因机制是上地幔岩部分熔融,两者之间的差异则是由部分熔融程度决定的。而壳层岩石(指堆积杂岩、岩墙杂岩、熔岩)则是由岩浆结晶作用形成的;堆积杂岩中出现辉石岩+辉长岩和橄长岩+辉长岩的不同岩石组合则与堆积岩岩浆房出露的深度和氧化状态有关。
In this paper ophiolites in the Western Zhungeer are divided into two types: One of them is assemblage of metamorphic peridotite + troctolite+ gabbro (abbreviated to PTG series); another is that of metamorphic peridotite +pyroxenite+gabbro (abbreviated to PPG series).The former is represented by the Dalabute and Hebukesaier belt; the latter is represented by the Tangbale and Mayileshan belt. The PTG and PPG series follow Al-rich and Ca-rich evolutional trend respectively. Therefore, two types ophiolites are very different in rock associations, mineralogy, rock chemistry, REE geochemistry and types of chromite deposits.Genetic mechanism of metamorphic peridotite in the ophiolites is partial melting of the upper mantle peridotite. Difference between two types ophiolites is dicided by degree of the partial melting. But, the crust rocks (included to accumulating complex, sheeted sill complex and lava) is formed by crystallization of the magma. The different rock associations of pyroxenite +gabbro and troctolite +gabbro in the accumulating complex are related to depth of formation of magmatic chambers and oxidation state of magma in the spreading ridge.
出处
《岩石矿物学杂志》
CAS
CSCD
1989年第4期299-310,共12页
Acta Petrologica et Mineralogica
关键词
蛇绿岩
岩石学
成因
新疆
the Western Zhungeer
two type ophiolites
petrologic characteristics
genetic discuss
