Basement (geology) in the context of "Fall line"

A craton ( /ˈkreɪtɒn/ KRAYT-on, /ˈkrætɒn/ KRAT-on, or /ˈkreɪtən/ KRAY-tən; from Ancient Greek: κράτος kratos "strength") is an old and stable part of continental lithosphere (the Earth's two topmost layers, the crust and the lithospheric mantle). Having often survived cycles of merging and rifting of continents, cratons are generally found in the interiors of tectonic plates; the exceptions occur where geologically recent rifting events have separated cratons and created passive margins along their edges. Cratons are composed of ancient crystalline basement rocks covered by younger sedimentary rocks. They have a thick crust and deep lithospheric roots extending several hundred kilometres into Earth's mantle.

Cratons contain the oldest continental crust rocks on Earth. They were formed in the Archaean (4 to 2.5 billion years ago) and the Proterozoic (2.5 billion- 538.8 million year ago) geologic eons. Most were formed in the Archaean.

The Sulu Archipelago (Tausug: Kapū'-pūan sin Sūg; Sulat Sūg: كَفُوْءْفُوْأَنْ سِنْ سُوْݢْ‎; Filipino: Kapuluan ng Sulu) is a chain of islands in the Pacific Ocean, in the southwestern Philippines. The archipelago forms the northern limit of the Celebes Sea and southern limit of the Sulu Sea. The Sulu Archipelago islands are within the Mindanao island group, consisting of the Philippines provinces of Basilan, Sulu, and Tawi-Tawi; hence the archipelago is sometimes referred to as Basulta, derived from the first syllables of the three provinces.

The archipelago is not, as is often supposed, the remains of a land bridge between Borneo and the Philippines. Rather, it is the exposed edge of small submarine ridges produced by tectonic tilting of the sea bottom. Basilan, Jolo, Tawi-Tawi and other islands in the group are extinct volcanic cones rising from the southernmost ridge. Tawi-Tawi, the southernmost island of the group, has a serpentine basement-complex core with a limestone covering. This island chain is an important migration route for birds.

The Variscan orogeny or Hercynian orogeny was a geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica (Laurussia) and Gondwana to form the supercontinent of Pangaea. It remains visible today as a series of isolated massifs, including the Ardennes, Bohemian Massif, Vosges-Black Forest, Armorican Massif, Cornubian Massif, Massif Central, and Iberian System. These are interspersed with Mesozoic and Cenozoic sedimentary basins. The chain also crops out in southern Ireland and was later incorporated into the Alpine orogeny (external crystalline massifs) and Pyrenean orogeny. These ancient massifs form the pre-Permian basement of western and Central Europe, part of a larger mountain system stretching from the Ural Mountains in Russia to the Appalachian Mountains in North America.

The chain originated from the convergence and collision of three continental masses: the microcontinent Armorica and the supercontinents Protogondwana and Laurussia (a union of Laurentia and Baltica from the Caledonian orogeny). This convergence contributed to the formation of the supercontinent Pangaea.

Voronezh Massif (also Voronezh Anteclise Russian: Воронежская антеклиза, or Voronezh Uplift) is a tectonic anteclise in the south of the Central Russian Upland with a high occurrence of the Precambrian basement. It lies to the southwest of the town of Voronezh, Russia.

The massif covers the southwest area of European Russia. Ukraine lies to the southwest, while Belarus is to the west. The massif is bordered northwest of the Orsha depression and Zhlobin saddle, south-west and south of the Pripyat-Donetsk aulacogens, east of the Caspian Basin, and northeast of the Moscow Basin. The Voronezh Massif stretches 800 kilometres (500 mi) from northwest to southeast, and between 300–400 kilometres (190–250 mi) wide.

Leucogranite is a light-colored, granitic, igneous rock containing almost no dark minerals.

Leucogranites have been reported from a variety of orogenies involving continental collisions. Examples include the Black Hills (Trans-Hudson orogeny of Proterozoic age), the Blue Ridge basement complex (Grenville orogeny of Proterozoic age), the Paleozoic Appalachian orogeny in Maine, and the currently active Himalayan orogeny. The leucogranite magmas are interpreted to have been derived by partial melting of pelitic rocks in the upper portions of thickened crust. These melts result following deformation and metamorphism, but the heat source is uncertain. Shear-heating associated with large shear zones in the crust has been proposed as the mechanism.

An accretionary wedge or accretionary prism forms from sediments accreted onto the non-subducting tectonic plate at a convergent plate boundary. Most of the material in the accretionary wedge consists of marine sediments scraped off from the downgoing slab of oceanic crust, but in some cases the wedge includes the erosional products of volcanic island arcs formed on the overriding plate.

An accretionary complex is a current (in modern use) or former accretionary wedge. Accretionary complexes are typically made up of a mix of turbidites of terrestrial material, basalts from the ocean floor, and pelagic and hemipelagic sediments. For example, most of the geological basement of Japan is made up of accretionary complexes.

The Lewisian complex or Lewisian gneiss is a suite of Precambrian metamorphic rocks that outcrop in the northwestern part of Scotland, forming part of the Hebridean terrane and the North Atlantic Craton. These rocks are of Archaean and Paleoproterozoic age, ranging from 3.0 to 1.7 billion years (Ga). They form the basement on which the Stoer Group, Wester Ross Supergroup and probably the Loch Ness Supergroup sediments were deposited. The Lewisian consists mainly of granitic gneisses with a minor amount of supracrustal rocks. Rocks of the Lewisian complex were caught up in the Caledonian orogeny, appearing in the hanging walls of many of the thrust faults formed during the late stages of this tectonic event.