广东省海岸表层沉积物的重矿物特征及其与沉积环境的关系

广东省海岸表层沉积物中的重矿物近40种。含量较高的有钛铁矿、赤矿铁、磁铁矿、话石、电气石、黑云母和普通角闪石等。自生矿物主要为硬石膏、自然铜、黄铁矿及菱铁矿。这些矿物来自附近的母岩。根据物源性质不同,可将不同岸段重矿物区分为陆源矿物组合、近源-自生矿物组合和近源矿物组合三种:除物源控制外,重矿物含量、种类、形态特征及其在平面上的分布主要受沉积环境影响。据此,可将重矿物分布类型划分为河口型、海湾型和海岛型三类,且与上述不同矿物组合性质相对应。

The Characteristics of Heavy Minerals in the Coastal Surficial Sediments of Guangdong province in Relation to Sedimentary Environments

There exist a variety of heavy minerals in coastal surficial sediments of Guangdong province, and nearly 40 sorts have been discovered in this study. Of them, the most important ones include ilmenite, hematite, magnetite, zircon, tourmaline, biotite and hornblende; next come epidote, diopside, tremolite and limonite. The authigenic minerals consist mainly of anhydrite, native copper, pyrite and siderite. These minerals are distributed along various coastal sections in different proportions and with different morphologic characteristics. An integrated study suggests that these heavy minerals are derived from source rocks with similar components, mainly granitoids and part of epimetamorphic and/or altered rocks, Nevertheless, in accordance with the differences in source materials, the heavy minerals might be grouped into terrigenous, near-soarce-authigenic and near-source mineral associations; in addition to the factor of material sources, it is mainly the sedimentary environments that control the contents ofheavy minerals, the types, morphologic characteristics and horizontal distribution of minerals in various coastal sections. The distribution patterns of heavy minerals controlled by different sedimentary environments might be classified into three types: (1) estuary pattern, predominated by river transportation; (2) harbor pattern, influenced chiefly by tidal sorting; and (3) island type, governed primarily by wave erosion. The three sorts of mineral associations as controlled by material sources are exactly consistent with the three distribution patterns of heavy minerals. Such a relationship has been well established for sediments of various coastal sections.