Why is the North America Cordillera high? Hot backarcs, thermal isostasy, and mountain belts
Why is the North America Cordillera high? Hot backarcs, thermal isostasy, and mountain belts
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DOI：
10.1130/g31998.1
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发表时间：
2011-08
期刊：
影响因子：
5.8
通讯作者：
R. Hyndman;C. Currie
中科院分区：
文献类型：
--
作者：
R. Hyndman;C. Currie
全球山带通常被认为是大陆碰撞导致地壳增厚的结果，地壳根部支撑着高海拔。然而，积累的地震构造数据表明，许多山脉带没有地壳根源。北美科迪勒拉大部分地区的地壳长度为30-35公里，相比之下，低海拔克拉通和其他稳定地区的地壳长度为40-45公里。以前已经表明，大多数这样的山脉带都处于现今或近代的背弧区，这些背弧区都是均匀热的。根据热约束，我们预测与稳定地区相比，科迪勒拉通过热膨胀得到的∼1600米高度支撑是均匀的。在科迪勒拉的大部分地区，相对于稳定区，经不同地壳厚度和密度校正后的高程非常一致。当俯冲和浅弧后对流停止时，岩石圈可能会冷却，山带的海拔在∼300m.y以上下降。
Global mountain belts are commonly concluded to be a consequence of crustal thickening resulting from continental collision, with high elevations supported by crustal roots. However, accumulating seismic structure data indicate that many mountain belts have no crustal root. Most of the North American Cordillera has a 30–35 km crust, in contrast to 40–45 km for the lower elevation craton and other stable areas. It has been shown previously that most such mountain belts are in present or recent backarcs that are uniformly hot. From thermal constraints, we predict a uniform ∼1600 m elevation support of the Cordillera by thermal expansion compared to stable areas. Over most of the Cordillera, relative to stable areas, the elevations after correction for variable crustal thickness and density are in excellent agreement. When subduction and shallow backarc convection stop, the lithosphere may cool and the elevations of mountain belts subside over ∼300 m.y.