Thermal regime of the Northern Hikurangi margin, New Zealand
Thermal regime of the Northern Hikurangi margin, New Zealand
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DOI：
10.1093/gji/ggy450
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发表时间：
2019-02-01
影响因子：
2.8
通讯作者：
Barker, Dan
中科院分区：
文献类型：
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作者：
Antriasian, Anson;Harris, Robert N.;Barker, Dan
我们用3.5米小提琴弓探头和地震反射剖面在新西兰北岛东海岸的Hikurangi北缘进行了96个新的海底热流测定。在这里，太平洋板块上的希库兰吉高原正在俯冲到澳大利亚板块之下。本底热流为58+/-8 mW m(-2)，与全球观测到的90-120 Ma洋壳热流(56+/-15 mW m(-2))的变化一致，且在此范围内。在形变前沿向海方向，我们发现了与基底起伏有关的平流流体流动的证据。在形变前沿的陆地上，我们使用了一个二维稳态有限元模型来量化热状况。尽管对底层水温变化、水深测量和沉积的影响进行了修正，但热流数据存在相当大的分散性，包括在最外面的楔形区域观测到的高达35兆瓦m(-2)的局部和急剧增加的热流。热流数据的可变性很可能是由于复杂的、未建模的三维流体流动造成的。我们用模拟海底反射和大陆井底温度的估计值来加强我们的热流测量，得出结论：在观察到的慢滑事件区域，有效摩擦系数*约为0.06，并在形变前锋向陆地方向约50公里处增加到0.18。*的这种转变可能标志着超压沿俯冲推覆的下降边缘，这表明超压使缓慢滑动成为可能。
We present 96 new seafloor heat flow determinations, made with a 3.5-m violin-bow probe and collocated with seismic reflection profiles, from the northern Hikurangi margin on the east coast of New Zealand's North Island. Here the Hikurangi Plateau on the Pacific Plate is subducting under the Australian Plate. The background heat flow is 58 +/- 8mW m(-2), consistent with and within the variability of globally observed heat flow (56 +/- 15mW m(-2)) for oceanic crust 90-120 Ma, the age of the Hikurangi Plateau. Seaward of the deformation front, we find evidence for advective fluid flow associated with basement relief. Landward of the deformation front, we use a 2-D steady-state finite-element model to quantify the thermal regime. Despite corrections for the effects of bottom water temperature change, bathymetry and sedimentation, there is considerable scatter in the heat flow data including a local and sharp increase in heat flow of up to 35mW m(-2) observed over the outermost wedge. Variability in the heat flow data is likely due to complex, unmodelled 3-D fluid flow. We augment our heat flow measurements with estimates from a bottom-simulating reflection and continental bottom hole temperatures and conclude that the effective coefficient of friction, *, is approximately 0.06 in the region of observed slow-slip events and increases to 0.18 approximately 50km landward of the deformation front. This transition in * may be marking the downdip edge of overpressures along the subduction thrust, suggesting that slow slip is enabled by overpressure.