Valley fills and coastal cliffs buried beneath an alluvial plain : evidence from variation of permeabilities in gravel aquifers, Canterbury Plains, New Zealand
Valley fills and coastal cliffs buried beneath an alluvial plain : evidence from variation of permeabilities in gravel aquifers, Canterbury Plains, New Zealand
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冲积平原下埋藏的山谷填土和沿海悬崖：新西兰坎特伯雷平原砾石含水层渗透率变化的证据
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发表时间：
1996
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影响因子：
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通讯作者：
A. Bal
中科院分区：
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作者：
A. Bal
大规模的内部结构的上部约。10 -200米的主要是砾石坎特伯雷平原进行了研究，利用渗透率的分布。地下水transmittance值，估计从特定的能力，除以屏幕长度近似水力传导率约。3，500口威尔斯井，并绘制渗透率和水力传导率图。半变异函数被用来检查的空间格局约。6,000平方公里的坎特伯雷平原。虽然威尔斯井的生产深度和含水层不同，但明显的低渗透率和高渗透率和水力传导率区域是显而易见的。五至六个相对高渗透率走廊，5- 10公里宽，倾向于与现今海岸线垂直，并切割低渗透率区域。这些走廊被推断为填充或掩埋的山谷，可能作为首选的地下水流路径。河谷发育于末次间冰期（130，000 - 75，000年B. P.）在最后一个冰川期（结束约。14，000年B. P.）。当山谷被切割时，海崖可能沿着沿着后退的海岸线发展，截断了山谷。随后，悬崖的掩埋导致悬崖边界两侧的沉积物结构、质地和含水层性质发生突变。高渗透性基督城自流含水层（如Riccarton或林伍德砾石）部分覆盖并邻接推断的前悬崖。这些含水层代表了类似于今天的Waimakariri河扇和洪泛平原的再加工沉积物。
The large-scale internal structure of the upper ca.10-200 m of the predominantly gravelly Canterbury Plains was investigated using the distribution of permeabilities. Groundwater transmissivity values, estimated from specific capacities, were divided by screen length to approximate hydraulic conductivities for ca. 3,500 wells and produce transmissivity and hydraulic conductivity maps. Semivariograms were used to examine spatial patterns over ca. 6,000 km 2 of the Canterbury Plains. Although the wells produce from different depths and aquifers, regions of distinctly low and high transmissivity and hydraulic conductivity are clearly apparent. Five to six relatively high permeability corridors, 5-10km wide, trend subperpendicular to the present-day coastline and dissect areas of low permeabilities. These corridors are inferred to be infilled or buried valleys that may act as preferred groundwater flow paths. The valleys developed during the last interglacial stage (130,000-75,000 yrs B.P.) and filled during the last glacial stage (ending ca. 14,000 yrs B.P.). Whilst the valleys were incising, sea cliffs probably developed along a retrograding shoreline, truncating the valleys. Subsequent burial of the cliff results in an abrupt change in sediment structure and texture and aquifer properties across the cliff boundary. High permeability Christchurch artesian aquifers (e.g. Riccarton or Linwood Gravels) partially cover and abut the inferred former cliffs. These aquifers represent reworked outwash deposits analogous to the present-day Waimakariri River fan and floodplain.