南海表层沉积物火山玻璃分布特征与源区分析

Distribution pattern of volcanic glasses in the surficial sediments of the South China Sea and their provenance

  • 摘要: 火山碎屑是边缘海沉积的重要来源,其分布特征对研究沉积作用与构造活动具有重要意义。对南海2276个表层站位碎屑矿物分析表明,664个站位含火山玻璃,占总站位数的29.17%,其中含量最高达95.8×10−3。表层沉积物火山玻璃主要出现在南海东部海域,往西呈逐渐降低趋势。南海东部主要重矿物磁铁矿和角闪石分布与火山玻璃十分相似,表明可能具有相同的来源。这些特征表明火山玻璃主要来自菲律宾群岛。这与南海东缘的琉球-台湾-菲律宾火山-地震带的吕宋岛大量活火山分布吻合。南海南缘苏门答腊-爪哇岛弧火山-地震带,虽然第四纪火山和地震活动频发,但对表层样火山玻璃贡献不大。南海海域火山可能有少量贡献,但不是主要因素,南海北缘及西缘基本没有贡献火山玻璃。

     

    Abstract: Pyroclast is a kind of important sediment source to marginal seas and the distribution of it is of great significance to the study of sedimentation and tectonic activities. In this paper, the detrital components from 2276 surficial samples of the South China Sea are studied. Volcanic glasses are found in 664 sites, accounting for 29.17%, of which the maximum is as high as 95.8×10−3. The volcanic glasses mainly occur in the eastern part of the South China Sea and gradually decrease westward. The distribution pattern of the main heavy minerals, such as magnetite and hornblende, is similar to that of volcanic glasses, indicating that they may have the same origin. Data suggests that volcanic glasses are mainly sourced from the Philippine islands. It is consistent with the distribution pattern of active volcanoes widely distributed in the Luzon island and partial Ryukyu-Taiwan-Philippines volcanic arc and seismic zone along the eastern margin of the South China Sea. The Sumatra-Java volcanic arc and seismic zone in the southern margin of the South China Sea, although there are frequent Quaternary volcanic and seismic activities, does not contribute much volcanic glasses to the surficial sediments. Volcanoes in the South China Sea are not the main contributor and the northern and western parts of the South China Sea have almost contributed nothing.

     

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