The Lateral Extent and Tectonic Significance of Late Miocene/Pliocene Inverted Metamorphism in the Himalaya

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9614869 Harrison Under normal circumstances, heat and pressure increase with depth in the earth's crust, however a number of cases of inverted metamorphic gradients are well documented in zones of tectonic deformation. This study involves the collection of data that will allow the testing of two competing hypotheses of "up-side-down" metamorphic sequences. One hypothesis holds that warmer rocks are thrust over cooler rocks which became heated from above, - producing an inverted thermal metamorphic sequence. The second hypothesis proposes that previously metamorphosed rocks, once cooled, are thrust over other previously metamorphosed but lower grade rocks. This leads to an up-side down gradient in the grade of ancient metamorphic conditions but does not reflect an instantaneous up-side-down temperature gradient. Results will be important in understanding the tectonic significance of many examples of inverse metamorphism.