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In geology, a terrane (/ t ə ˈ r eɪ n, ˈ t ɛr eɪ n /; [1] [2] in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or "sutured" to crust lying on another plate. The crustal block or fragment preserves its distinctive geologic history, which is different from the ...
When mapping the metamorphic grade of a terrane, a geologist has to take the lithology of the rock in account. Lithologies are mainly dependent on the protolith, the original rock before metamorphism. The main lithologies are ultramafic, mafic, felsic (or quartzo-feldspathic), pelitic and calcareous. In all of these (and other) lithologies ...
An example of using thermal modeling in P-T-t path reconstruction. The above diagram shows the calculated geothermal gradients upon crustal thickening at 0 million year (m.y.) followed by an immediate uplift event at a rate of 1 mm per year. The P-T-t evolution of a rock originally at 40 km below ground is marked as red dots on the diagram.
Legend: green: terrane (microplate) boundaries in the continental blocks; cyan: terranes of the oceanic plates; orange: terranes inside the mobile belts; blue: oceanic transform faults; red: fault zones in the continental and mountain belt domain; purple: main subduction zones and suture zones; orange dots: volcanoes. African plate
Diagram (modified from Fig 3.11 in Irwin, 1990) showing the depositional setting of the Franciscan Assemblage and the contemporaneous Great Valley Sequence,. [ 5 ] The Franciscan Complex is an assemblage of metamorphosed and deformed rocks, associated with east-dipping subduction zone at the western coast of North America. [ 6 ]
Triangular diagrams showing the aluminium (A), calcium (C) and iron (F) content of the main phases (dark dots) in metamorphic rocks in various facies. Thin grey lines are stable phase equilibria. Triangular diagrams showing the aluminium (A), iron (F) and magnesium (M) content of the main phases (dark dots and, when the composition can vary ...
Some zircon with age as great as 4.3 billion years has been found in the Narryer Gneiss Terrane. Continental crust is a tertiary crust, formed at subduction zones through recycling of subducted secondary (oceanic) crust. [17] The average age of Earth's current continental crust has been estimated to be about 2.0 billion years. [20]
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