Late Quaternary stream incision and uplift in the forearc of the Cascadia subduction zone
Late Quaternary stream incision and uplift in the forearc of the Cascadia subduction zone
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卡斯卡迪亚俯冲带弧前的晚第四纪河流切割和隆升
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
S. Personius
中科院分区：
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作者：
S. Personius
俄勒冈海岸山脉最新更新世/最早全新世地层形成和河流加积的记录提供了确定长期基岩流切割率的数据。长期切割率的变化可能反映了卡斯卡迪亚俯冲带前弧的累积差异隆起，尽管基岩和气候控制以及侵蚀的均衡调整等因素模糊了地表隆起和河流切割之间的精确关系。差异切口模式在纽波特纬度附近最为显着，陡峭的梯度将北部海岸山脉的高速率区域（~0.6-0.9 毫米/年）与中部海岸山脉的低速率区域（~0.1-0.3 毫米/年）分开。陡峭的切割梯度几乎与海洋阶地（~80-125 kyr）抬升率、第四纪断层位置以及历史低位（~40-70 年）抬升鞍部南侧的突然变化一致。这些不同的切口/隆起模式的确切原因尚不清楚。与其他俯冲带隆起模式的类比以及与该地区其他新构造数据的比较表明，差异切割模式可能是由沿着卡斯卡迪亚俯冲带的永久应变积累的变化引起的。这种变化可能与各次地震期间地震矩释放的差异、板块几何形状或楔形增生速率的变化、地震破裂的分割和/或北美板块和增生楔中活动结构的变形有关。
Documentation of a latest Pleistocene/earliest Holocene episode of strath formation and fluvial aggradation in the Oregon Coast Range provides a datum from which long- term bedrock stream incision rates are determined. Variations in long-term incision rates probably reflect cumulative differential uplift in the forearc of the Cascadia subduction zone, although factors such as bedrock and climatic controls and isostatic adjustments to erosion obscure the precise relationship between surface uplift and stream incision. Patterns of differential incision are most striking near the latitude of Newport, where a steep gradient divides a region of higher rates (~0.6-0.9 mm/yr) in the northern Coast Range from a region of lower rates (~0.1-0.3 mm/yr) in the central Coast Range. The steep incision gradient is nearly coincident with abrupt changes in marine terrace (~80-125 kyr) uplift rates, the locations of Quaternary faults, and the southern flank of a saddle of low historic (~40-70 years) uplift. The exact causes of these variable patterns of incision/uplift are unknown. Analogies with uplift patterns in other subduction zones and comparisons with other neotectonic data in the region indicate that patterns of differential incision probably are caused by variations in permanent strain accumulation along the Cascadia subduction zone. Such variations may be related to differences in seismic moment release during individual earthquakes, to changes in plate geometry or rates of wedge accretion, to segmentation of earthquake ruptures, and/or to deformation on active structures in the North American plate and accretionary wedge.