Tectonics of the San Gabriel Basin and surroundings, southern California
Tectonics of the San Gabriel Basin and surroundings, southern California
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南加州圣盖博盆地及周边地区的构造
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发表时间：
2004
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通讯作者：
R. Yeats
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作者：
R. Yeats
圣盖博盆地是上新世-更新世横断山脉构造，北部以圣盖博山脉为界，东部以圣何塞山和普恩特山为界，西部以雷佩托山和蒙特贝洛山为界。圣盖博山脉面的片麻状岩石和半岛山脉岩石之间的基底边界向东穿过盆地并与圣何塞断层连接。这一边界可能代表了广东断层向东的延续，广东断层是圣加布里埃尔断层系统的中中新世前体，右滑达30公里。广东断层位移在很大程度上被雷蒙德断层前体上的22.5 km左滑移所抵消，因此圣何塞山的渐新世英安岩及其碎屑几乎没有证据表明圣加布里埃尔山和普恩特山之间存在大的水平位移。中新世中期的白垩纪旋转可能影响了侧向滑动的分布。东北向上新世-更新世圣盖博盆地的充填是一个基底浅海层序，上覆有非海相Duarte砾岩，与洛杉矶盆地的深水Fernando组形成对比。古斜坡向南延伸至Repetto山和Puente山的方向，这表明这些山的隆起滞后于沉积。三角形的圣加布里埃尔盆地目前是一个稳定的块体，其西部是右滑、西北走向的东蒙特贝洛断层，东部是东北走向的核桃溪断层。再往东，圣何塞和普恩特山下面是一条东向活动褶皱带，包括圣何塞逆断层和背斜、核桃背斜和与右侧惠蒂尔断层相邻的普恩特山背斜。东蒙特贝洛断层的西部以洛杉矶市中心的一个褶皱带--极乐公园复背斜为界。左滑全新世雷蒙德断层加入马德雷山脉逆断层在其段边界标志着蛤壳锯断层。东向褶皱带之间的三角形稳定块体南部以Puente Hills盲冲断层为界，北部以Sierra Madre断层为界，记录了南北第四纪收敛。还显示了东西延伸，但没有得到大地测量的证实。
The SanGabriel Basin is a Pliocene–Pleistocene Transverse Ranges structure bounded by the San Gabriel Mountains on the north, the San Jose and Puente Hills on the east, and the Repetto and Montebello Hills on the west. A basement boundary between gneissoid rocks of San Gabriel Mountains aspect and Peninsular Ranges rocks strikes east across the basin and connects with the San Jose fault. This boundary may represent the eastward continuation of the Canton fault, a middle Miocene precursor of the San Gabriel fault system with up to 30 km of right slip. Canton fault displacement is largely canceled by ∼22.5 km of left slip on a precursor to the Raymond fault such that an Oligocene dacite in the San Jose Hills and clasts derived from it show little evidence of large horizontal displacement between the San Gabriel Mountains and Puente Hills. Clockwise rotation in the middle Miocene probably influenced the distribution of lateral slip. The fill in the northeast-trending Pliocene–Pleistocene San Gabriel Basin is a basal shallow-marine sequence overlain by the nonmarine Duarte Conglomerate, in contrast to the deep-water Fernando Formation of the Los Angeles Basin. The paleoslope trends south in the direction of the Repetto and Puente Hills, evidence that uplift of these hills postdated deposition. The triangular San Gabriel Basin is currently a stable block bounded by the right-slip, northwest-striking East Montebello fault on the west and the left-slip(?), northeast-striking Walnut Creek fault on the east. Farther east, the San Jose and Puente Hills are underlain by an east-trending active fold belt, including the San Jose reverse fault and anticline, the Walnut anticline, and the Puente Hills anticline adjacent to the right-lateral Whittier fault. The East Montebello fault is bounded on the west by the Elysian Park anticlinorium, a fold belt in downtown Los Angeles. The left-slip Holocene Raymond fault joins the Sierra Madre reverse fault at its segment boundary marked by the Clamshell-Sawpit fault. The triangular stable block between east-trending fold belts is bounded on the south by the Puente Hills blind thrust and on the north by the Sierra Madre fault, documenting north-south Quaternary convergence. East-west extension is also indicated, although not confirmed by geodetic measurements.