DOMINANCE FACTORS OF THE TERRIGENOUS SEDIMENT GRANULOMETRIC DISTRIBUTION IN THE LOWER SUNDA SLOPE
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摘要: 通过对"太阳号"115航次18268-2孔陆源碎屑高分辨率沉积粒度分析,获取了大约2.5万年以来巽他陆坡下部沉积物粒度分布特征的详细记录。结果显示,该孔陆源碎屑颗粒较细,粒径在2~10 μm之间的含量最高,几乎不含大于63 μm的颗粒。沉积物粒度分布的均值和中值与粒径在10~63 μm之间的百分含量相关性较好,说明古水流速度决定着沉积物粒度分布在短时间尺度上的变化。14.6~14.3 kaBP期间海平面迅速上升造成海岸线后退数百千米,使本地区沉积物供应产生了明显的变化,从而造成所有统计参数及各组分相对百分含量在15 kaBP前后均发生了明显变化,这说明沉积物供应控制着沉积物粒度分布较长时间尺度上的变化。Abstract: High resolution grain size analysis was performed on sediments of Core 18268-2, drilled during the "SONNE-115" cruise. Detailed granulometric distribution record of lower Sunda slope sediments for the last 25 ka was obtained. The analysis revealed that sediments in this core were fine grained, predominated by 2~10 μm grains and short of grains larger than 63 μm. Statistical parameters such as mean and median values of the grain size were highly correlative with the relative percentage of the 10~63 μm fraction, implying that short-term change of the sediment grain size distribution was controlled by the paleocurrent speed. All statistical parameters and the relative percentage of the fractions underwent a notable transformation at about 15 ka, attributed to the rapid rising of the sea level during the MWP-1a (Melt Water Pulse 1a, 14.6~14.3 ka). Simultaneous with the rapid flooding of the Sunda shelf, the coastline retreated for several hundred kilometers, which changed the sediment supply of the region dramatically. We can conclude that the relative long-term variation of the siliclastic sediment granulometric distribution was controlled by the sediment supply.
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Key words:
- granulometric distribution /
- dominance factor /
- sediment supply /
- hydrodynamics /
- Sunda slope
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