【摘要】 浊流和碎屑流等粗粒沉积是深海油气和天然气水合物良好的储层,它的发现和识别对于深海油气和天然气水合物的勘探具有重要意义。在南海北部陆坡神狐海域水深1805 m海底采集的长5.5 m柱状沉积物由2层富有孔虫层和2层深灰色泥质粉砂层相间组成,其中深灰色泥质粉砂层（A₁和A3_）主要为黏土矿物、石英和长石组成,粒径中值在6¹5μm之间,Ti/Al、K/Al和Fe/Al比值类似于南海神狐海域表层半深海沉积特征,而富有孔虫砂层（A₂和A₄）的粒度具有向上递减的特征,形成由粗到细的正粒序构造,粒径中值高,Ti/Al、K/Al和Fe/Al比值较高,与A₁和A₃灰色泥质粉砂层相比,含有更多的粗粒陆源物,推测可能是浊流经底流改造的碎屑流沉积。浮游有孔虫¹⁴C定年表明下部的A₄层可能晚于42.46⁴3.53 ka B P,A₂层晚于15.1¹5.3ka B P。浊流从浅海搬运来的大量有孔虫在陆坡经碎屑流改造形成富集Ca CO₃的有孔虫富集层。更多还原

【Abstract】 Deep-water turbidite and debris flow in submarine canyons can be reservoir favorable for marine gas hydrate and deep-water oil, so their discovery and identification could be significant for prospecting of marine gas hydrate and deep-sea oil. For sediments in gravity core DH-1 collected in Shenhu area on the northern continental slope of the South China Sea at water depth of 1805 m, they are composed of two Foraminifera-rich layers（A₂ and A₄） and two dark-gray clay silt layers（A₁ and A₃）. Major element chemistry and grain size and minerals analysis suggest that these dark-gray clay silt layers represent background hemipelagic sediments. The intervening Foraminifera-rich layers（A₂ and A₄）, which exhibit a large median grain size range, are debris flow and turbidite resulted from bottom current reconstruction. Their relatively high Ti/Al, K/Al and Fe/Al ratios and carbonate contents as well as higher median grain size imply a more coarse detrital materials input. Radiocarbon dating of hemipelagic sediments indicates that the age of the turbidity in A₂ and A₄ could be later than 42.46⁴3.53 ka BP and 15.1¹5.3 ka BP, respectively. These data indicate that the abundant Foraminiferal brought by turbidite from shallow-water and bottom current was reconstructed, and causes the enrichment of Ca CO₃ in Foraminifera-rich layers.更多还原