Chromite deposits in the northern Oman ophiolite: Mineralogical constraints
Chromite deposits in the northern Oman ophiolite: Mineralogical constraints
复制标题
DOI：
10.1007/bf00204235
复制
发表时间：
1987
影响因子：
4.8
通讯作者：
T. Augé
中科院分区：
文献类型：
--
作者：
T. Augé
阿曼北方蛇绿混杂岩中的铬铁矿矿床存在于三种构造环境中，(1)（2）地幔序列的上千米;（3）地幔深部。类型1和2的特点是多样性的填隙式硅酸盐，其中在丰度下降的顺序橄榄石，单斜辉石，斜方辉石，斜长石，角闪石发生，而不是类型3只包含橄榄石。然而，它们的矿石结构不同。类似的硅酸盐也以自形包裹体形式存在于铬铁矿晶体中，但它们的比例相反。填隙硅酸盐的组成是可比的，发现在早期堆积。第1型和第2型铬铁矿矿床结晶自与形成基底堆晶的岩浆相似的岩浆（Al 2 O3，15.1-16.1重量%; FeO/MgO，0.55-0.60）。3型铬铁矿来自于Al 2 O3含量低得多的岩浆（12.5wt%）。认为它们属于该杂岩岩浆演化中较老的一幕。
Chromite deposits in the northern Oman ophiolitic complex occur in three structural contexts, i.e., (1) at the base of the cumulate series, (2) in the top kilometer of the mantle sequence, and (3) in the deeper parts of the mantle. Types 1 and 2 are characterized by the diversity of interstitial silicates where in decreasing order of abundance olivine, clinopyroxene, orthopyroxene, plagioclase, and amphibole occur, as opposed to type 3 which contains only olivine. They differ however in ore texture. Similar silicates also occur as euhedral inclusions in chromite crystals, but their proportions are reversed. The composition of the interstitial silicates is comparable to that found in early cumulates. Type-1 and type-2 chromite deposits crystallized from a magma similar to that from which the basal cumulates formed (Al2O3, 15.1–16.1 wt%; FeO/MgO, 0.55–0.60). The type-3 chromites were derived from a magma of much lower Al2O3content (12.5 wt%). It is considered that they belong to an older episode in the magmatic evolution of the complex.