Burial pressures (depths) within mountain belts place fundamental constraints on the growth and stabilization of continental crust. We report precise metamorphic pressures for ca. 1.7 Ga rocks from the Upper Granite Gorge (UGG) of the Grand Canyon (southwestern United States) and, for the first time, resolve pressure variations across this continuous exposure of mid-crustal rocks. We applied quartz-in-garnet (QuiG) barometry and pseudosection modeling to determine pressures in domains (“blocks”) with evidence of higher and lower peak metamorphic grades. New pressure-temperature (P-T) paths constructed using this integrated approach show that a hot block sample reached 7 kbar and a cold block sample never surpassed 5 kbar, revealing an ~2 kbar P difference between hot and cold blocks and delineating distinct P-T paths for these domains in the UGG. Our findings suggest that hot and cold blocks were likely metamorphosed at different crustal levels within a pre-Yavapai, Paleoproterozoic orogen and were subsequently juxtaposed during and/or after the Yavapai Orogeny at mid-crustal levels. The deformation that produced differential vertical displacement of crustal blocks post-dated peak metamorphism and could reflect extensional collapse of a large orogen and/or renewed folding and thrusting at the Paleoproterozoic Laurentian plate margin.

中文翻译：

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解决大峡谷前寒武纪基底内的压力差异：对元古代构造的影响

山脉内的埋藏压力（深度）对大陆地壳的生长和稳定产生了根本性的限制。我们报告了大约的精确变质压力。来自大峡谷（美国西南部）上部花岗岩峡谷 (UGG) 的 1.7 Ga 岩石，首次解决了中地壳岩石连续暴露的压力变化。我们应用石榴石中石英 (QuiG) 气压测量和伪截面建模来确定域（“块”）中的压力，并提供较高和较低峰值变质等级的证据。使用这种集成方法构建的新压力-温度 (PT) 路径表明，热块样本达到 7 kbar，冷块样本从未超过 5 kbar，揭示了热块和冷块之间约 2 kbar P 差异，并描绘了不同的 PT 路径UGG 中的这些域。我们的研究结果表明，热块和冷块可能在前亚瓦派古元古代造山带内的不同地壳层面发生变质，随后在亚瓦派造山运动期间和/或之后在中地壳层面并置。在远期的峰值变质作用之后，产生地壳块差异垂直位移的变形可以反映大型造山带的伸展塌陷和/或古元古代劳伦斯板块边缘的新折叠和逆冲。