Leucogranite (alaskite) from Colorado, USA, containing potassium feldspar and quartz
Leucogranite from Lozère, FranceLeucogranite of the Boscobel complex, Virginia
Leucogranite is a light-colored, granitic, igneous rock containing almost no dark minerals. Alaskite is a synonym.[1]
Leucogranites have been reported from a variety of orogenies involving continental collisions. Examples include the Black Hills (Trans-Hudson orogeny of Proterozoic age),[2] the Blue Ridge basement complex (Grenville orogeny of Proterozoic age),[3] the Paleozoic Appalachian orogeny in Maine, and the currently active Himalayan orogeny.[2] 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.[2] Shear-heating associated with large shear zones in the crust has been proposed as the mechanism.[2]
Mont Saint-Michel in Normandy, France is made of leucogranite, which solidified from an underground intrusion of molten magma about 525 million years ago during the Cambrian period.[4]
A study of sodium-rich quartz-alkali feldspar—biotite gneiss granulite facies terrane in the Kerala Khondalite Belt near Manali in south India found that in situ leucosomes (light colored segregations) within the gneiss showed the development of garnet replacing the dark biotite. The study indicated localized melting or migmatization within the gneiss. This was followed by intrusion of the gneiss by garnet-bearing leucogranitic melts both parallel and discordant to the foliation of the gneiss. Strontium isotope ratios of the leucogranite intrusives are distinct from that of the gneiss and associated leucosomes. This indicates the leucogranite melts were not derived from the local gneiss, however the gneiss is isotopically variable and the leucogranite could have derived from subjacent gneiss.[5]
^Glossary Archived 2012-04-26 at the Wayback Machine
^ abcdPeter I. Nabelek and Mian Liu, Petrologic and thermal constraints on the origin of leucogranites in collisional orogens, Transactions of the Royal Society of Edinburgh: Earth Sciences, 95, 73–85, 2004 Archived 2015-10-06 at the Wayback Machine
^Alkali feldspar leucogranite, Mineral Resources, Online Spatial Data, Virginia, USGS
^L'Homer, A.; et al. (1999). Notice explicative, Carte géol. France (1/50 000), feuille Baie du mont-Saint-Michel (208)(PDF) (in French). Orléans: BRGM. ISBN 2-7159-1208-0.
^Braun I., G.R. Ravindra Kumar, and M. Raithi, (1996) Dehydration—Melting Phenomena in Leptynitic Gneisses and the Generation of Leucogranites: a Case Study from the Kerala Khondalite Belt, Southern India, Journal of Petrology, Vol. 37, No. 6, pp. 1285-1305
Leucogranite is a light-colored, granitic, igneous rock containing almost no dark minerals. Alaskite is a synonym. Leucogranites have been reported from...
numerous sills and dikes of leucogranite ranging in thickness from 1 cm to 1,500 m (0.4 in to 4,900 ft). These leucogranites are part of a belt of Late...
Examples for this structure are found in California in the Mount Rubidoux leucogranite and in granodiorites in the Sierra Nevada. During Ca- metasomatism myrmekite...
rocks also contain mica or amphibole minerals, though a few (known as leucogranites) contain almost no dark minerals. Granite is nearly always massive (lacking...
Eocene Period to form gneiss. Later, the K2 Gneiss was then intruded by leucogranite dikes and finally exhumed and uplifted along major breakback thrust faults...
with some alkali feldspar. The leucogranite is primarily quartz and feldspar with some garnet. Sample of the leucogranite Gneiss sample The type section...
volcanic complex where basalt of the Nido Formation overlies Tertiary leucogranite. Thick deposits of tufa formed by the precipitation of calcite and aragonite...
plutons in southwestern Patagonia. The rocks of batholith include granite, leucogranite, tonalite, granodiorite, diorite, gabbro and mafic dykes. The earliest...
leucogranite (two mica granites). The granodiorite can be found at Finisterre, western Salamanca, Zamora, Gredos, Aracena. The two mica leucogranites...
spatially very close to the northern edge of the Chéronnac Leucogranite, a Pennsylvanian leucogranite with a very pronounced, east-west-striking foliation....
of the commune. The geology consists mainly of grey or light orange leucogranite and orthogneiss rich in biotite, sillimanite, and cordierite with alternating...
compositionally distinct phases: a fine-grained, peraluminous, two-mica leucogranite with a radiometric age of 1632±45 Ma, a medium-grained equigranular monzogranite...
and was intruded with hornblende-rich granitoids and muscovite-rich leucogranites. List of orogenies Payne, J.L. and co-authors (2009). "Evolution of...
outlet. Spectacular outcrops of gneisses, mylonites, and a series of leucogranite dykes were beautifully exposed along the valley walls." Strachey, Physical...
kimberlite) Feldspathoid-bearing rocks such as leucitites K-feldspar enriched leucogranites Vaugnerite and Durbachite The economic importance of ultrapotassic rocks...
of kyanite- to sillimanite-grade gneisses intruded by High Himalayan leucogranites at structurally higher levels. Throughout much of the range, the unit...
Mountains. The pluton contains apparent roof pendants of amphibolite or leucogranite. It is intruded by the Joaquin quartz monzonite. The gneiss was named...
Peak Geology Age of rock Cretaceous Mountain type Fault block Type of rock Granodiorite, Leucogranite Climbing First ascent 1935 Easiest route class 2...
20 years. Uranium mineralisation is hosted primarily within sheeted leucogranites that intruse the rocks at various stages during the Damara Orogeny....
elevated section of the Murrumbidgee granite batholith and adjacent Yaouk leucogranites and Ordovician metasediments. This elevated block is heavily dissected...
it is poor in xenoliths and is coarse grained. Booroomba Leucogranite Booroomba Leucogranite is found at Mount Tennant and Booroomba Rocks. The total...
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