低温低压二氧化硅集合体的存在形式、产出特征与资源分布

The modes of occurrence,characteristics and distribution of silica aggregates formed at low temperature and low pressure

低温低压二氧化硅集合体在全球分布广泛,近年来因在众多领域中的多样应用而备受关注。低温低压二氧化硅相主要包括α-石英、α-鳞石英、α-方石英、斜硅石和蛋白石5种,并可聚集形成结晶程度不同的二氧化硅集合体——非晶质的opal-A、隐晶质的opal-CT/C和玉髓以及隐晶质-显晶质的粒状石英集合体。低温低压二氧化硅集合体在火成岩、沉积岩和变质岩中均可出现,不同类型二氧化硅集合体的产状、围岩类型、围岩年龄和资源分布特征通常存在一定的差异和规律性,这些规律往往能够为该资源的开发利用以及其成因的探讨提供一定指导和借鉴意义。本文在综合现有文献的基础上对此进行了归纳总结。此外,虽然形成时的地质环境对二氧化硅集合体的存在形式和产出特征起到了决定的作用,但后期环境的变化在某些情况下也发挥着重要影响,故对特定地区二氧化硅集合体存在形式和产出特征的判断,有时还需要结合共生矿物组合的特征等进行综合考虑。

Silica aggregates formed at low temperature and low pressure(LTLP) are distributed widely in the world and have aroused more and more attention for their various applications in many fields.Silica phases that occur at LTLP include α-quartz,α-cristobalite,moganite and opal,often as various kinds of silica aggregates:opalline opal-A,cryptocrystalline opal-CT/C and chalcedony,cryptocrystalline-phanerocrystalline granulous quartz aggregates.These silica aggregates could exist in host rocks with different geneses;however,there still exist some discrepancies and regularities in their occurrence and distribution as well as types and ages of their host rocks,which can provide some guidance and reference not only for the development and utilization of these resources but also for the discussion of their genesis.In this paper,discrepancy and regularity were summarized based on the available references.Besides determinative influence of geological environment on the existing form and occurrence of silica aggregates,the environment plays an important role.Thus,we should combine paragenetic minerals which can reflect some information of geological activities to evaluate the existing form and occurrence of silica aggregates in specific regions.