PRELIMINARY DISCUSSION ON METALLOGENIC SERIES OF PRIMARY DIAMOND DEPOSITS
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摘要: 目前所知产金刚石的岩石类型包括金伯利岩、钾镁煌斑岩、榴辉岩、蛇绿岩套、碱性超基性杂岩、碱性超基性煌斑岩和橄榄岩类(方辉橄榄岩、纯橄榄岩等) 等偏碱性超镁铁质岩石, 而有经济价值的金刚石原生矿床仅见于金伯利岩和钾镁煌斑岩中, 除此之外的其他岩石类型中仅见有少量微粒金刚石.金伯利岩和钾镁煌斑岩都起源于地幔深部, 就此意义上讲, 二者是同源的, 但其岩石化学成分、主要矿物组成、产出大地构造背景以及同位素资料等, 却存在着比较明显的差异.由此构成了金刚石原生矿床的两个成矿系列: 金伯利岩成矿系列和钾镁煌斑岩成矿系列.金伯利岩成矿系列又可以根据其化学成分划分为3个亚系列, 即: 高Cr, Ti, Mg成矿亚系列, 低Cr, Ti, Mg成矿亚系列和介于二者之间的一种具有复杂化学成分的成矿亚系列.钾镁煌斑岩成矿系列则可以根据其主要矿物组成, 划分出橄榄石钾镁煌斑岩成矿亚系列、白榴石钾镁煌斑岩成矿亚系列以及介于两者之间的白榴石-橄榄石钾镁煌斑岩成矿亚系列共3种次级成矿系列.与此同时, 无论是金伯利岩成矿系列, 还是钾镁煌斑岩成矿系列, 又都可以根据其野外地质产状, 划分为以下3个成矿亚系列(形成时间从早到晚) : (1) 火山沉积凝灰岩成矿亚系列; (2) 火山凝灰角砾岩成矿亚系列; (3) 火山-次火山侵入相成矿亚系列.Abstract: Up to now, the known diamond bearing rocks, pro alkaline and ultra mafic, include kimberlite, lamproite, eclogite, ophiolite suite, alkaline ultrabasic complex, alkaline ultrabasic lamprophyre, peridotite series (including harzburgite and dunite). However, the primary diamond deposits worthy of exploration in terms of economic value occur only in the kimberlite and lamproite. In addition, only a small amount of micro grain diamond occurs in other types of rocks. Although both kimberlite and lamproite originated from the deep mantle, relatively conspicuous differences arise in chemical compositions, rock forming minerals, tectonic settings, and isotope data, resulting in two metallogenic series of primary diamond deposits: kimberlite type and lamproite type primary diamond metallogenic series. The kimberlite type primary diamond metallogenic series is divided into three sub series of mineralization in terms of chemical compositions: rich Cr, Ti and Mg kimberlite type diamond metallogenic sub series, poor Cr, Ti and Mg kimberlite type diamond metallogenic sub series, and the kimberlite sub series with complex chemical compositions (of transitional type) between the first two sub series. However, the lamproite type primary diamond metallogenic series is classified in terms of major mineral components as olivine lamproite primary diamond metallogenic sub series, leucite lamproite primary diamond metallogenic sub series and the transitional subseries lying between the first two subseries. In the meantime, both the kimberlite type metallogenic series and the lamproite metallogenic series can be classified as three metallogenic subseries (from early to late) respectively in terms of their corresponding field geological occurrences: kimberlite/lamproite type volcanic sedimentary tuff primary diamond metallogenic sub series, kimberlite/lamproite type volcanic tuff and breccia primary diamond metallogenic sub series, and kimberlite/lamproite type volcanic subvolcanic intrusion facies primary diamond metallogenic sub series.
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Key words:
- kimberlite /
- lamproite /
- primary diamond deposit /
- metallogenic series /
- the deep mantle
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