|
Ranquil Formation
The Ranquil Formation ( es, Formación Ranquil) is a Miocene and Pliocene sedimentary formation located in Arauco Province in south–central Chile, including outcrops in Mocha Island. The formation has its greatest thicknesses in the south-west, where its sediments were largely deposited in marine conditions. It overlies unconformably sedimentary formations of the Paleocene-Eocene Lebu Group. The formation is part of the fill of Arauco Basin which is a sedimentary basin that extends south of Concepción. Macrofossils of the formation are similar to those of Navidad ( 34° S) and Lacui Formations ( 43° S), two nearby Miocene marine formations. The base of the Ranquil Formation is the so-called "main unconformity", which is thought to have been formed by erosion during a period of tectonic inversion. The formation was first defined in 1942 by Juan Tavera. Units The formation has been subdivided into five units, with the lowermost being made up of sandstone and shale, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness (geology), thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arauco Province
Arauco Province ( es, Provincia de Arauco) is one of four provinces of the Chilean region of Bío Bío. It spans a coastal area of just south of the mouth of the Biobío River, the traditional demarcation between the nation's major natural regions, Zona Central and Zona Sur. The province originally covered the once-independent indigenous territory of Araucanía, but this was afterward divided into four provinces. It is devoted largely to agricultural pursuits. The capital Lebu (population 25,000) is situated on the coast about south of Concepción with which it is connected by rail. Administration As a province, Arauco is a second-level administrative division of Chile, governed by a provincial governor who is appointed by the president. Communes The province is composed of seven communes, each governed by a municipality consisting of an elected alcalde and municipal council A municipal council is the legislative body of a municipality or local government area. Dependin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacui Formation
Lacui Formation ( es, Formación Lacui) is a marine Miocene sedimentary formation located in Chiloé Island with minor outcrops near Carelmapu on the mainland. Gastropod shells are the most common macrofossils of Lacui Formation. According to Sernageomin (1998) the formation dates to the earliest Serravallian — that is the Middle Miocene. South of Lacui Formation there are equivalent sedimentary rocks in the islands of Ipún, Lemo and Stoke. See also * Lacuy Peninsula * Navidad Formation Navidad Formation ( es, Formación Navidad) is a marine Neogene sedimentary formation located in Central Chile. The formation is known for its diverse and abundant fossil record and is considered the reference unit for the marine Neogene in Chile ... * Santo Domingo Formation References {{Geology of Chile Geologic formations of Chile Neogene Chile Serravallian Miocene Series of South America Laventan Chiloé Archipelago Geology of Los Lagos Region ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
34th Parallel South
The 34th parallel south is a circle of latitude that is 34 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Australasia, the Pacific Ocean and South America. At this latitude the sun is visible for 14 hours, 28 minutes during the December solstice and 9 hours, 50 minutes during the June solstice, and south of which the Crux constellation is circumpolar (figures in the sky all year round). On 21 June, the maximum altitude of the sun is 32.00 degrees, while it's 79.00 degrees on 21 December. Around the world Starting at the Prime Meridian and heading eastwards, the parallel 34° south passes through: : See also *33rd parallel south *35th parallel south The 35th parallel south is a circle of latitude that is 35 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, the Indian Ocean, Australasia, the Pacific Ocean and South America. At this latitude the sun is visible ... {{geographical coordi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Navidad Formation
Navidad Formation ( es, Formación Navidad) is a marine Neogene sedimentary formation located in Central Chile. The formation is known for its diverse and abundant fossil record and is considered the reference unit for the marine Neogene in Chile. Originally described by Charles Darwin in 1846 the formation has attracted the attention of numerous prominent geologists and paleontologists since then. As a key formation Navidad has been subject to a series of differing interpretations and scientific disputes over time. History Charles Darwin saw the formation in September 1834 during the second voyage of HMS Beagle. He became the first to describe it 1846 when he published his book Geological Observations on South America in 1846 and it was named by Darwin after the nearby town of Navidad. In this book Darwin calls the formation "Formation of Navidad" and "Sandstone Formation at Navidad". There are no signs of that Darwin would have attempted to make a formal definition of the fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrofossil
Macrofossils, also known as megafossils, are preserved organic remains large enough to be visible without a microscope. The term ''macrofossil'' stands in opposition to the term microfossil. Microfossils, by contrast, require substantial magnification for evaluation by fossil-hunters or professional paleontologists. As a result, most fossils observed in the field and most "museum-quality" specimens are macrofossils. Varieties Plant macrofossils Plant macrofossils include leaf, needle, cone, and stem debris; and can be used to identify types of plants formerly growing in the area. Such botanical macrofossil data provide a valuable complement to pollen and faunal data that can be used to reconstruct the prehistoric terrestrial environment. Algal macrofossils (for instance, brown kelp, sea lettuce and large stromatolites) are increasingly used to analyze prehistoric marine and aquatic ecosystems. Animal macrofossils Animal macrofossils include the teeth, skulls, and bon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concepción, Chile
Concepción (; originally: ''Concepción de la Madre Santísima de la Luz'', "Conception of the Blessed Mother of Light") is a city and commune in central Chile, and the geographical and demographic core of the Greater Concepción metropolitan area, one of the three major conurbations in the country. It has a significant impact on domestic trade being part of the most heavily industrialized region in the country. It is the seat of the Concepción Province and capital of the Bío Bío Region. It sits about 500 km south of the nation's capital, Santiago. The city was first settled in the Bay of Concepción, in the zone that would later become the commune of Penco, now part of the Concepción conurbation. The city's demonym, , comes from the place of its original foundation. The city center and historic district is located in the Valle de la Mocha (La Mocha Valley), where it relocated after serious damages left by an earthquake in 1751. The origin of Concepción dates b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentary Basin
Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock. They form when long-term subsidence creates a regional depression that provides accommodation space for accumulation of sediments. Over millions or tens or hundreds of millions of years the deposition of sediment, primarily gravity-driven transportation of water-borne eroded material, acts to fill the depression. As the sediments are buried, they are subject to increasing pressure and begin the processes of compaction and lithification that transform them into sedimentary rock. Sedimentary basins are created by deformation of Earth's lithosphere in diverse geological settings, usually as a result of plate tectonic activity. Mechanisms of crustal deformation that lead to subsidence and sedimentary basin formation include the thinning of underlying crust; depression of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arauco Basin
The Arauco Basin ( es, Cuenca de Arauco) is a sediment-filled depression –a sedimentary basin– in south-central Chile. In the context of plate tectonics it is classified as a forearc basin. The basin has an approximate area of and at its deeper parts the surface of its sedimentary fill reaches below sea-level. The basin is interpreted as being part of an uplifted part of the continental shelf. To the west it bounds an active accretionary prism that lies next to the Chile trench and to the east it bounds metamorphic basement representing a fossil Paleozoic accretionary complex that has been intruded by the Coastal Batholith of central Chile. Traditionally the centre of coal mining in Chile, large-scale coal mining in Arauco Basin ended in the 1990s.Explotacion Rese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eocene
The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " dawn") and (''kainós'', "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch. The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C. The end is set at a major extinction event called the ''Grande Coupure'' (the "Great Break" in continuity) or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay. As with other geologic periods, the strata that define the start and e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleocene
The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''palaiós'' meaning "old" and the Eocene Epoch (which succeeds the Paleocene), translating to "the old part of the Eocene". The epoch is bracketed by two major events in Earth's history. The K–Pg extinction event, brought on by an asteroid impact and possibly volcanism, marked the beginning of the Paleocene and killed off 75% of living species, most famously the non-avian dinosaurs. The end of the epoch was marked by the Paleocene–Eocene Thermal Maximum (PETM), which was a major climatic event wherein about 2,500–4,500 gigatons of carbon were released into the atmosphere and ocean systems, causing a spike in global temperatures and ocean acidification. In the Paleocene, the continents of the Northern Hemisphere were still connected v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unconformity
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger layer, but the term is used to describe any break in the sedimentary geologic record. The significance of angular unconformity (see below) was shown by James Hutton, who found examples of Hutton's Unconformity at Jedburgh in 1787 and at Siccar Point in 1788. The rocks above an unconformity are younger than the rocks beneath (unless the sequence has been overturned). An unconformity represents time during which no sediments were preserved in a region or were subsequently eroded before the next deposition. The local record for that time interval is missing and geologists must use other clues to discover that part of the geologic history of that area. The interval of geologic time not represented ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
