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Angular unconformity. An angular unconformity is an unconformity where horizontally parallel strata of sedimentary rock are deposited on tilted and eroded layers, producing an angular discordance with the overlying horizontal layers. [6] The whole sequence may later be deformed and tilted by further orogenic activity. A typical case history is ...
[10] [11] The contact between the overlying Tapeats Sandstone and the folded and faulted Nankoweap Formation is a prominent angular unconformity that is part of the Great Unconformity. [7] Uranium-lead dating of detrital zircons from the Nankoweap Formation indicate the presence of zircon grains in approximately the 800–770 Ma age range. This ...
Hutton's Unconformity is a name given to various notable geological sites in Scotland identified by the 18th-century Scottish geologist James Hutton as places where the junction between two types of rock formations can be seen. This geological phenomenon marks the location where rock formations created at different times and by different ...
Throughout the majority of it extent, the Tonto Group lies unconformably on underlying Precambrian rocks forming the Great Unconformity. This contact is either an angular unconformity truncating tilted strata of the Grand Canyon Supergroup or a nonconformity cut into the crystalline Vishnu Basement Rocks. The base of the Tonto Group consists of ...
The unconformity between the Tonto Group and the Vishnu Basement Rocks is a nonconformity. The break between the Tonto Group and the Grand Canyon Supergroup is an angular unconformity. [2] [3] [4] Powell's Great Unconformity is part of a continent-wide unconformity that extends across Laurentia, the ancient core of
angular unconformity An unconformity in which younger strata overlie an erosion surface of tilted or folded layered rock. anorthite. Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals.
Angular unconformity: younger sediment lies upon an eroded surface of tilted or folded older rocks. The older rock dips at a different angle from the younger. Disconformity : the contact between younger and older beds is marked by visible, irregular erosional surfaces .
Second, an angular unconformity, with a dip of less than 10°, separates the base of the Nankoweap Formation from the underlying Unkar Group. Finally, a well-defined angular unconformity at the base of the relatively flat-lying Tonto Group separates it from the underlying faulted and folded strata of the Unkar Group and the rest of the Grand ...