Porosity and Compaction State at the Active Pāpaku Thrust Fault in the Frontal Accretionary Wedge of the North Hikurangi Margin
Porosity and Compaction State at the Active Pāpaku Thrust Fault in the Frontal Accretionary Wedge of the North Hikurangi Margin
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北希库朗吉边缘正面增生楔内活跃 Pāpaku 逆冲断层的孔隙度和压实状态
DOI：
10.1029/2020gc009325
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发表时间：
2021
期刊：
影响因子：
3.7
通讯作者：
Y. Géraud
中科院分区：
文献类型：
--
作者：
J. Dutilleul;S. Bourlange;Y. Géraud
对进入俯冲带和沉积带的沉积剖面孔隙度演化特征的描述，为了解沉积边缘的变形历史以及断裂带内部和周围的物理化学过程提供了有价值的信息。国际海洋发现计划探险队372和375在进入板块（U1520地点）和活跃的Pāpaku逆冲断层（U1518地点）的参考部分进行了钻探、测井和取芯，这是位于北Hikurangi边缘的前缘沉积楔中的一个<30°向西倾斜的展断层，该地区记录了海啸地震和周期性慢滑事件。我们观察到逆冲断层的物理性质有很大的变化。特别是，间隙孔隙度在断裂带中增加~ 10%，而随深度呈指数下降，显示上盘的孔隙度（HW，平均为~ 36%）低于下盘的孔隙度（~ 42%）。通过对比U1518和参考U1520站点的压实曲线和孔隙度，我们推断在HW处存在过压实，在Pāpaku逆冲下盘存在接近正常的压实。我们认为，冲断带上的孔隙度模式推断出沉积物最大埋藏深度的差异，其特征是在下盘上方被抬升、冲断并伴随构造侵蚀的过压实HW。孔隙度数据表明逆冲断层周围的流体静力条件与通常假定的板块界面超孔隙压力形成对比。
Characterization of the porosity evolution across the sedimentary section entering subduction zones and accreted sediments provide valuable information for understanding the deformation history at accretionary margins and the physico‐chemical processes in and around fault zones. International Ocean Discovery Program Expeditions 372 and 375 drilled, logged, and cored the reference section on the incoming plate (Site U1520) and across the active Pāpaku thrust (Site U1518), which is a <30° westward‐dipping splay fault in the frontal accretionary wedge at the north Hikurangi margin in a region where tsunami earthquakes and recurrent slow slip events are documented. We observe strong variations of physical properties across the thrust fault. In particular, interstitial porosity increases by ∼10% through the fault zone while it exponentially decreases with depth, showing lower values in the hanging‐wall (HW; on average, ∼36%) than in the footwall (∼42%). Based on comparisons of porosity with the compaction curve at Site U1518 with that of reference Site U1520, we infer an overcompaction in the HW and a nearly normal compaction in the footwall of the Pāpaku thrust. We suggest that the porosity pattern across the thrust infers differences in the maximum burial depth of sediments, characterized by an overcompacted HW that has been uplifted, thrusted, and concomitantly tectonically eroded above the footwall. Porosity data indicate hydrostatic conditions around the thrust fault contrasting with commonly assumed excess pore pressure at the plate interface.
影响因子：
18.3
作者：
Wallace, Laura M.;Kaneko, Yoshihiro;Fry, Bill
通讯作者：
Fry, Bill
孔隙流体压力和强度对比维持新西兰北希库朗吉边缘的额断层活动
影响因子：
5.2
作者：
French, Melodie E.;Morgan, Julia K.
通讯作者：
Morgan, Julia K.
影响因子：
56.9
作者：
Huepers, Andre;Torres, Marta E.;Zhao, Xixi
通讯作者：
Zhao, Xixi