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A rock formation is an isolated, scenic, or spectacular surface rock outcrop. Rock formations are usually the result of weathering and erosion sculpting the existing rock. The term rock formation can also refer to specific sedimentary strata or other rock unit in stratigraphic and petrologic studies.
The youngest oceanic rocks are at the oceanic ridges, and they get progressively older away from the ridges. [17] As the mantle rises it cools and melts, as the pressure decreases and it crosses the solidus. The amount of melt produced depends only on the temperature of the mantle as it rises. Hence most oceanic crust is the same thickness (7± ...
The same phenomenon occurs near oceanic ridges in a formation known as hydrothermal vents. [5] The final line of evidence supporting the origin of ophiolites as seafloor is the region of formation of the sediments over the pillow lavas: they were deposited in water over 2 km deep, far removed from land-sourced sediments. [5]
Mid-ocean ridges exhibit active volcanism and seismicity. [3] The oceanic crust is in a constant state of 'renewal' at the mid-ocean ridges by the processes of seafloor spreading and plate tectonics. New magma steadily emerges onto the ocean floor and intrudes into the existing ocean crust at and near rifts along the ridge axes. The rocks ...
The Zambales Ophiolite Complex (also called Zambales Ophiolite) is a large, well-preserved exposure of oceanic crust located in the western portion of Luzon Island, Philippines. [1] It is considered one of the best-preserved and most studied ophiolites , offering valuable insights into the formation and evolution of oceanic crust and the ...
The bottom units represent the crystallized magma chamber, feeding the mid-ocean ridge at which the crust was formed. It is composed of 1–5 km thick layered gabbro atop <7 km thick layer of ultramafic rocks (e.g. wehrlite, harzburgite, dunite, and chromite). [12] Oceanic crust is referred to as a metabasite. [13]
A sheeted dyke complex, or sheeted dike complex, is a series of sub-parallel intrusions of igneous rock, forming a layer within the oceanic crust. [1] At mid-ocean ridges , dykes are formed when magma beneath areas of tectonic plate divergence travels through a fracture in the earlier formed oceanic crust, feeding the lavas above and cooling ...
The Franciscan Formation of California – Franciscan rocks in the Bay Area range in age from about 200 million to 80 million years old. The Franciscan Complex is composed of a complex amalgamation of semi-coherent blocks, called tectonostratigraphic terranes, that were episodically scraped from the subducting oceanic plate, thrust eastward ...