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Brand Group
The Brand Group is a geologic group in Leicestershire. It preserves Ichnotaxon dating back to the Cambrian period. It mainly contains pelites, with greywacke and breccia. Formation units It is made up of two formations. Uppermost within the group is the Swithland Formation, consisting of purple pelites and fine greywackes, with thin discontinuous shale-pebble conglomerates at its base. This is underlain by the Brand Hills Formation, which consists of quartzarenite interbedded with pelite, greywackes and berrica. In stratigraphical order, i.e. uppermost/youngest first: *Swithland Formation *Brand Hills Formation **Stable Pit Quartzarenite Member Dating With the discovery of '' Teichichnus'' in the Swithland Formation, alongside several other ichnogenera, researchers have been able to confidentially date the Brand Group to the Lower Cambrian, which led to the group being taken out of the Charnian Supergroup, and has also led to the research and discovery of a major hiatu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Group (stratigraphy)
In geology, a group is a lithostratigraphy, lithostratigraphic Stratigraphic unit, unit consisting of a series of related Geological formation, formations that have been classified together to form a group. Formations are the fundamental unit of stratigraphy. Groups may sometimes be combined into Supergroup (geology), supergroups. Groups are useful for showing relationships between formations, and they are also useful for small-scale mapping or for studying the stratigraphy of large regions. Geologists exploring a new area have sometimes defined groups when they believe the strata within the groups can be divided into formations during subsequent investigations of the area. It is possible for only some of the strata making up a group to be divided into formations. An example of a group is the Glen Canyon Group, which includes (in ascending order) the Wingate Sandstone, the Moenave Formation, the Kayenta Formation, and the Navajo Sandstone. Each of the formations can be distingui ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelite
A pelite () or metapelite is a metamorphism, metamorphosed fine-grained sedimentary rock, i.e. mudstone or siltstone. The term was earlier used by geologists to describe a clay-rich, fine-grained clastic sediment or sedimentary rock, i.e. mud or a mudstone, the metamorphosed version of which would technically have been a ''metapelite''. It was equivalent to the now little-used Latin-derived term lutite.Potter, P.E., J.B. Maynard, and P.J. Depetris (2005) ''Muds and Mudstones.'' New York, New York, Springer. 279 pp. Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. A semipelite is defined in part as having similar chemical composition but being of a crystalloblastic nature. Francis J. Pettijohn, Pettijohn (1975) gives the following descriptive terms based on grain size, avoiding the use of terms such as clay or Argillite, argillaceous which carry an implication of chemic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian Europe
The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 486.85 Ma. Most of the continents lay in the southern hemisphere surrounded by the vast Panthalassa Ocean. The assembly of Gondwana during the Ediacaran and early Cambrian led to the development of new convergent plate boundaries and continental-margin arc magmatism along its margins that helped drive up global temperatures. Laurentia lay across the equator, separated from Gondwana by the opening Iapetus Ocean. The Cambrian marked a profound change in life on Earth; prior to the Period, the majority of living organisms were small, unicellular and poorly preserved. Complex, multicellular organisms gradually became more common during the Ediacaran, but it was not until the Cambrian that fossil diversity seems to rapidly increas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Fossiliferous Stratigraphic Units In The United Kingdom
*List of fossiliferous stratigraphic units in England See also * Lists of fossiliferous stratigraphic units in Europe * Lists of fossiliferous stratigraphic units in the United Kingdom References * {{DEFAULTSORT:Fossiliferous stratigraphic units in England England England is a Countr ... * List of fossiliferous stratigraphic units in Wales * List of fossiliferous stratigraphic units in Scotland * List of fossiliferous stratigraphic units in Northern Ireland {{DEFAULTSORT:Fossiliferous stratigraphic units in the United Kingdom * * United Kingdom geology-related lists United Kingdom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White Sea Assemblage
The White Sea assemblage was the second of the three Late Ediacaran biotic assemblages, following the Avalon assemblage and preceding the Nama assemblage. It spanned from 560 Ma to 550 Ma. Showing an increase in genus diversity from the Avalon assemblage, it concluded with a faunal turnover often characterized as the first pulse of the end-Ediacaran extinction, with only 20% of White Sea taxa found in the later Nama assemblage despite similar taphonomic Taphonomy is the study of how organisms decay and become fossilized or preserved in the paleontological record. The term ''taphonomy'' (from Greek , 'burial' and , 'law') was introduced to paleontology in 1940 by Soviet scientist Ivan Efremov ... processes. References Ediacaran {{Ediacaran-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avalon Assemblage
The Avalon assemblage was the first of the three Late Ediacaran biotic assemblages, spanning from 575 Ma to 560 Ma. It was followed by the White Sea assemblage, although temporal overlaps have been noted between the biotic assemblages. While earlier macroscopic fossils, mostly of algal origin, are known from the Lantian Formation, Avalon-type localities provide some of the first evidence of putative metazoan ancestors, as part of the Ediacaran biota. Research history The division of the Ediacaran biota in three separate assemblages was first postulated by Ben Waggoner in 2003. Geography Most Avalonian fossil sites are known from the central United Kingdom and eastern Newfoundland, historically connected as part of the Avalonia microcontinent. Outside of Avalonia proper, other sites have been identified as part of the Avalon assemblage, such as the Olenek Uplift in Siberia, and Sekwi Brooke in the Northwest Territories of Canada. Biota Deep-water rangeomorphs, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diorite
Diorite ( ) is an intrusive rock, intrusive igneous rock formed by the slow cooling underground of magma (molten rock) that has a moderate content of silica and a relatively low content of alkali metals. It is Intermediate composition, intermediate in composition between low-silica (mafic) gabbro and high-silica (felsic) granite. Diorite is found in mountain-building belts (''orogens'') on the margins of continents. It has the same composition as the fine-grained volcanic rock, andesite, which is also common in orogens. Diorite has been used since prehistoric times as decorative stone. It was used by the Akkadian Empire of Sargon of Akkad for funerary sculptures, and by many later civilizations for sculptures and building stone. Description Diorite is an intrusive rock, intrusive igneous rock composed principally of the silicate minerals plagioclase feldspar (typically andesine), biotite, hornblende, and sometimes pyroxene. The chemical composition of diorite is Intermedia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charnian Supergroup
The Charnian Supergroup is a geologic supergroup in the United Kingdom, and is a part of the wider Charnwood terrane. It preserves fossils dating back to the Ediacaran and through into the Cambrian period, with suggestions that the Brand Group and Maplewell Groups have a major hiatus in-between. It mainly contains volcaniclastics, but is interrupted by and succeeded by greywackes, and is interbedded with pelites, tuffs. Due to the thickness of the Supergroup, it spans over , with a possible lower date of and a maximum upper date of . This also means that it spans across two Ediacaran assemblages, with the Blackbrook Group and part of the lower Maplewell Group sitting within the Avalon assemblage, whilst the rest of the Maplewell Group sits within the White Sea assemblage. The Brand Group was originally a part of the supergroup, until the discovery of several ichnogenera, like '' Teichichnus'', which helped to date it to the Lower Cambrian, and was subsequently taken out of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teichichnus
''Teichichnus'' is an ichnogenus with a distinctive form produced by the stacking of thin 'tongues' of sediment, atop one another. They are believed to be fodinichnia, with the organism adopting the habit of retracing the same route through varying heights of the sediment, which would allow it to avoid going over the same area. These 'tongues' are often quite sinuous, reflecting perhaps a more nutrient-poor environment in which the feeding animals had to cover a greater area of sediment, in order to acquire sufficient nourishment. ''Teichichnus'' is recognized as a series of tightly packed, concave-up or down laminae, and lacks an outside border or lining, which distinguishes ''Teichichnus'' from the ''Diplocraterion'' ichnogenus An ichnotaxon (plural ichnotaxa) is "a taxon based on the fossilized work of an organism", i.e. the non-human equivalent of an artifact. ''Ichnotaxon'' comes from the Ancient Greek (''íchnos'') meaning "track" and English , itself derived from .... ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratigraphy
Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostratigraphy (lithologic stratigraphy), biostratigraphy (biologic stratigraphy), and chronostratigraphy (stratigraphy by age). Historical development Catholic priest Nicholas Steno established the theoretical basis for stratigraphy when he introduced the law of superposition, the principle of original horizontality and the principle of lateral continuity in a 1669 work on the fossilization of organic remains in layers of sediment. The first practical large-scale application of stratigraphy was by William Smith in the 1790s and early 19th century. Known as the "Father of English geology", Smith recognized the significance of strata or rock layering and the importance of fossil markers for correlating strata; he created the first geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quartzarenite
A quartz arenite or quartzarenite is a sandstone composed of greater than 90% detrital quartz. Quartz arenites are the most mature sedimentary rocks possible, and are often referred to as ultra- or super-mature, and are usually cemented by silica. They often exhibit both textural and compositional maturity. The two primary sedimentary depositional environments that produce quartz arenites are beaches/upper shoreface and aeolian processes Aeolian processes, also spelled eolian, pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth (or other planets). Winds may erosion, erode, transport, and deposit ....Prothero, D. R. and Schwab, F., 1996, Sedimentary Geology, pg. 96-98, See also * * References Further reading * * * * * sandstone sedimentary rocks {{petrology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
