Holocene sediment deposition on the Poverty-slope margin by the muddy Waipaoa River, East Coast New Zealand
Holocene sediment deposition on the Poverty-slope margin by the muddy Waipaoa River, East Coast New Zealand
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DOI：
10.1016/j.margeo.2004.06.001
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发表时间：
2004-08
期刊：
影响因子：
2.9
通讯作者：
A. Orpin
中科院分区：
文献类型：
--
作者：
A. Orpin
新西兰北岛东海岸劳德代尔半岛边缘的特点是陆源沉积物通量高、历史上土地利用变化的巨大影响、中生代和第三纪软沉积物的快速隆起，以及在陡峭和不稳定的大陆坡上复杂的沉积-构造相互作用。贫困湾大陆架和斜坡凹陷与Waipaoa河相邻，该河每年输送1.15亿吨泥浆。这项研究提出了新的数据，从贫困的斜坡，向海延伸的Waipaoa分散系统。一个3公里3的冰后期沉积物的叶出现从贫困差距和羽毛下降到上斜坡。下坡，贫困压痕收到了显着的全新世通量的陆源沉积物，积累在两个中坡盆地：帕里图槽和南帕里图山脊下方的一个较小的低坡盆地。自全新世中晚期以来，半大洋沉积物以约0.05 g cm-2 year-1（0.06 cm year-1）的速度在中坡堆积。地震反射回波类型和反向散射图像表明，在中坡有泥浆沉积物，在上坡有规则间隔的冲沟底部有碎片，在上帕里图海槽有一个大的雪崩存款。火山灰地层学的一致性表明，尽管斜坡不稳定，半远洋沉积是占主导地位的背景过程，在千年的时间尺度上运行，至少自中全新世。贫困斜坡应包括在殖民后增加的边际产沙量的任何预算计算中。贫困峡谷可能在全新世高水位期基本上是不活跃的。
The margin off the Raukumara Peninsula, East Coast North Island of New Zealand, is characterised by high terrigenous sediment flux, the dramatic effects of historic land-use change, the rapid uplift of Mesozoic and soft Tertiary sediments, and by complex sediment-tectonic interactions on a steep and unstable continental slope. The Poverty Bay shelf and slope indentation are adjacent to the Waipaoa River, which delivers ∼15 Mt year−1of mud. This study presents new data from the Poverty slope, the seaward extension of the Waipaoa dispersal system. A 3-km3lobe of postglacial sediment emerges from the Poverty Gap and feathers down onto the upper slope. Downslope, the Poverty indentation has received a significant Holocene flux of terrigenous sediment, accumulating in two mid-slope basins: the Paritu Trough and a smaller lower-slope basin below the South Paritu ridge. Hemipelagic sediment has accumulated on the mid-slope at around 0.05 g cm−2year−1(0.06 cm year−1) since the mid–late Holocene. Seismic-reflection echo type and backscatter imagery indicate mud deposits on the mid-slope, debris at the base of regularly spaced upper-slope gullies and a large avalanche deposit in the upper Paritu Trough. The consistency of the tephrostratigraphy indicates that despite slope instability, hemipelagic sedimentation is the dominant background process operating at millennial time scales, at least since the mid-Holocene. The Poverty slope should be included in any budget calculation of post-colonisation increased sediment yield for the margin. The Poverty Canyon has probably been largely inactive during the Holocene highstand.