Multichronometer thermochronologic modeling of migrating spreading ridge subduction in southern Patagonia
Multichronometer thermochronologic modeling of migrating spreading ridge subduction in southern Patagonia
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DOI：
10.1130/g46091.1
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发表时间：
2019-06-01
期刊：
影响因子：
5.8
通讯作者：
Fosdick, Julie C.
中科院分区：
文献类型：
--
作者：
Goddard, Andrea L. Stevens;Fosdick, Julie C.
扩张脊俯冲对上覆板块地质的动态影响已被用来解释科迪勒拉系统中上板块地形、侵蚀速率和模式以及区域应力状态的变化。本研究使用巴塔哥尼亚安第斯山脉南部（南纬 47 度至南 54 度）55 个样本的造山带规模热年代学建模数据集来推导相对于中新世山脊俯冲和板片窗口就位的岩石冷却时空模式。这些结果确定了岩石冷却向北迁移的记录，并解释了整个弧基和弧后从 20 Ma 到 5 Ma 的抬升，该抬升早于智利海岭扩张中心俯冲 2 米。我们将此信号解释为来自巴塔哥尼亚的第一个造山带规模的证据，表明山脊俯冲环境中的岩石隆起和侵蚀主要是由沿倾斜俯冲山脊前缘生成的增厚地壳带所驱动的。该信号在距离海沟>160公里的构造域中是一致的，这表明山脊俯冲不会仅在弧后褶皱逆冲带中引发集中变形，正如所暗示的那样。此外，岩石冷却在 10-20 m.y 内停止。板片窗口安置的影响，表明软流圈上升流和加热不会在板片窗口上方的上地壳中产生可测量的热重置。需要多个测温仪来模拟时间-温度历史，以捕获与智利海脊俯冲相关的向北迁移的隆起和岩石冷却，这一信号仅从热测时年龄中并不明显。
The dynamic effects of spreading ridge subduction on the geology of the overriding plate have been used to account for changes in upper-plate topography, erosion rates and patterns, and regional stress regimes in Cordilleran systems. This study used an orogen-scale thermochronological modeling data set of 55 samples in the southern Patagonian Andes (47 degrees S-54 degrees S) to derive the spatio-temporal patterns of rock cooling relative to Miocene-present ridge subduction and slab window emplacement. These results identify a northward-migrating record of rock cooling and interpreted uplift from 20 Ma to 5 Ma throughout the arc batholith and retroarc that predate the subduction of the Chile Ridge spreading center by 2- m.y. We interpret this signal as the first orogen-scale evidence from Patagonia that rock uplift and erosion in ridge subduction settings are primarily driven by the generation of a thickened crustal welt along the leading edge of the obliquely subducting ridge. This signal is uniform across tectonic domains >160 km from the trench, indicating that ridge subduction does not trigger concentrated deformation only in the retroarc fold-and-thrust belt, as has been suggested. Moreover, rock cooling ceases within 10-20 m.y. of slab window emplacement, suggesting that asthenospheric upwelling and heating do not produce measurable thermal resetting in the upper crust above the slab window. Multiple thermochronometers are required to model the time-temperature histories that capture northward-migrating uplift and rock cooling associated with subduction of the Chile Ridge, a signal that is not evident from thermochronometric ages alone.