Colorado Basin, Argentina
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The Colorado Basin ( es, Cuenca del Colorado) is a
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 ...
located in northeastern
Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...
. The basin stretches across an area of approximately , of which onshore in the southern
Buenos Aires Province Buenos Aires (), officially the Buenos Aires Province (''Provincia de Buenos Aires'' ), is the largest and most populous Argentine province. It takes its name from the city of Buenos Aires, the capital of the country, which used to be part of th ...
and the easternmost
Río Negro Province Río Negro (, ''Black River'') is a province of Argentina, located in northern Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean. Its capit ...
extending offshore in the
South Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe and ...
. The basin comprises a sedimentary succession dating from the
Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...
(pre-rift stage) and
Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145  Ma to 100.5 Ma. Geology Pro ...
(rift stage) to the
Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...
, representing the
passive margin A passive margin is the transition between oceanic and continental lithosphere that is not an active plate margin. A passive margin forms by sedimentation above an ancient rift, now marked by transitional lithosphere. Continental rifting creat ...
tectonic phase of the basin history. The Mesozoic rifting in the basin resulted from the break-up of
Pangea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...
and the formation of the South Atlantic. Long hiatuses exist in the succession. The basin is of paleontological significance for hosting fossiliferous stratigraphic units dating to the
Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...
. The Arroyo Chasicó Formation defines the
Chasicoan The Chasicoan ( es, Chasiquense or es, Chasicoense) age is a period of geologic time from 10–9 Ma within the Late Miocene epoch of the Neogene, used more specifically within the SALMA classification in South America. It follows the Mayoan and ...
South American land mammal age The South American land mammal ages (SALMA) establish a geologic timescale for prehistoric South American fauna beginning 64.5 Mya (unit), Ma during the Paleocene and continuing through to the Late Pleistocene (0.011 Ma). These periods are referre ...
and contains a rich mammal and other vertebrate fauna. The contemporaneous
Cerro Azul Formation The Cerro Azul Formation ( es, Formación Cerro Azul), in the Buenos Aires Province also described as Epecuén Formation, is a geological formation of Late Miocene (Tortonian, or Huayquerian in the SALMA classification) age in the Colorado Basin ...
has provided fossil
rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...
s,
armadillo Armadillos (meaning "little armored ones" in Spanish) are New World placental mammals in the order Cingulata. The Chlamyphoridae and Dasypodidae are the only surviving families in the order, which is part of the superorder Xenarthra, along wi ...
s and
opossum Opossums () are members of the marsupial order Didelphimorphia () endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 93 species in 18 genera. Opossums originated in South America and entered North ...
s. The Middle to Late Miocene
Gran Bajo del Gualicho Formation Gran may refer to: People *Grandmother, affectionately known as "gran" *Gran (name) Places * Gran, the historical German name for Esztergom, a city and the primatial metropolitan see of Hungary * Gran, Norway, a municipality in Innlandet count ...
contains vertebrate fossils of the
cetacea Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...
n '' Preaulophyseter gualichensis''. The Río Negro Formation has provided fossils of the
glyptodont Glyptodonts are an extinct subfamily of large, heavily armoured armadillos. They arose in South America around 48 million years ago and spread to southern North America after the continents became connected several million years ago. The best-kn ...
'' Plohophorus figuratus''. The Permian succession in the basin has provided
flora Flora is all the plant life present in a particular region or time, generally the naturally occurring (indigenous) native plants. Sometimes bacteria and fungi are also referred to as flora, as in the terms '' gut flora'' or '' skin flora''. E ...
microfossil A microfossil is a fossil that is generally between 0.001 mm and 1 mm in size, the visual study of which requires the use of light or electron microscopy. A fossil which can be studied with the naked eye or low-powered magnification, ...
s. Contrasting with the South Atlantic passive margin basins to the north (
Santos Basin The Santos Basin ( pt, Bacia de Santos) is an approximately large mostly offshore sedimentary basin. It is located in the south Atlantic Ocean, some southeast of Santos, Brazil. The basin is one of the Brazilian basins to have resulted from th ...
in southern Brazil) and south;
Golfo San Jorge The San Jorge Gulf (Golfo San Jorge; Spanish for ''Gulf of St. George'') is a bay in southern Patagonia, Argentina. It is an ocean basin opening to the Atlantic. Its shoreline spans Chubut and Santa Cruz province. The gulf measures approximatel ...
and Austral Basins, the Colorado Basin does not produce hydrocarbons. Exploration for petroleum started in the 1940 with the drilling of two onshore wells and several onshore and offshore wells have been drilled in the 1960s, 1970s and 1990s. The main
source rock In petroleum geology, source rock is rock which has generated hydrocarbons or which could generate hydrocarbons. Source rocks are one of the necessary elements of a working petroleum system. They are organic-rich sediments that may have been depos ...
s are found in the Permian succession, with reservoir rocks the Colorado Formation.
Seals Seals may refer to: * Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particularly: ** Earless seal, or "true seal" ** Fur seal * Seal (emblem), a device to impress an emblem, used as a means of a ...
are provided by the
Early Paleocene The Danian is the oldest age or lowest stage of the Paleocene Epoch or Series, of the Paleogene Period or System, and of the Cenozoic Era or Erathem. The beginning of the Danian (and the end of the preceding Maastrichtian) is at the Cretaceo ...
Pedro Luro Formation.


Description

The Colorado Basin stretches across an approximate area of with about onshore, underlying the southernmost
Buenos Aires Province Buenos Aires (), officially the Buenos Aires Province (''Provincia de Buenos Aires'' ), is the largest and most populous Argentine province. It takes its name from the city of Buenos Aires, the capital of the country, which used to be part of th ...
and the southeasternmost
Río Negro Province Río Negro (, ''Black River'') is a province of Argentina, located in northern Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean. Its capit ...
. Cities inside the basin are
Bahía Blanca Bahía Blanca (; English: White Bay) is a city in the southwest of the provinces of Argentina, province of Buenos Aires Province, Buenos Aires, Argentina, by the Atlantic Ocean, and is the seat of government of the Bahía Blanca Partido. It had 3 ...
and
Carmen de Patagones Carmen de Patagones is the southernmost city in the . Geography It is located 937 km southwest from the city of Buenos Aires, on the north bank of the Río Negro ("Black River"), near the Atlantic Ocean, and opposite Viedma, capital of ...
in Buenos Aires Province and Viedma in Río Negro Province, the earliest founded city in
Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...
. The onshore part of the basin is crossed by the eponymous
Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of t ...
and Río Negro rivers. Surrounding the Río Negro, many
salt lake A salt lake or saline lake is a landlocked body of water that has a concentration of salts (typically sodium chloride) and other dissolved minerals significantly higher than most lakes (often defined as at least three grams of salt per litre). ...
s are present in the basin.Geologic Map Hojas 4163-II/IV & I/III, 2006 Some authors group the basin together with the Claromecó Basin to the north.Balarino, 2012, p.344 The offshore part of the Colorado Basin laterally correlates with and gradually ranges into the sub-parallel Salado Basin and the deeper offshore Argentina Basin.Pucci, 2006, p.17ENARSA, s.a., p.3 The offshore extension of the basin into neighboring basins led to different definitions of its area, some authors use a surface area of .ENARSA, s.a., p.2 The Colorado Basin is bound to the north by the Ventania High,Daners et al., 2016, p.285
Sierra de la Ventana Sierra de La Ventana is a village in Tornquist Partido in the southwest of the Province of Buenos Aires, Argentina. With a population of 1,819 inhabitants (), it is one of the most attractive tourist centres in the Province and has numerous recreat ...
,Balarino, 2009, p.20 or Sierras Australes, separating the basin from the Claromecó Basin, and to the south by the
Rawson Rawson may refer to: Places *Rawson, Chubut, the capital of Chubut Province, Argentina *Rawson Department, Chubut, Argentina *Rawson Department, San Juan, Argentina **Villa Krause, also named Rawson, the capital city of the department * Rawson, Vic ...
,ENARSA, s.a., p.1 or Río Negro High. In the northwest, the basin grades into the Macachín Basin and the western boundary is formed by the
San Rafael Block The San Rafael Block or San Rafael Massif (Spanish: ''Bloque de San Rafael'' or ''Macizo de San Rafael'') is an uplifted area in central Mendoza Province, Argentina. The San Rafael Block is both a geographic and a tectonic unit. From a tectonostra ...
.Barredo & Stinco, 2010, p.60


Basin evolution

The basin started forming in the Middle to
Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...
with the break-up of
Pangea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...
and the formation of the Southern Atlantic.Geologic Map Hojas 3963-III & IV, 2009, p.42 The main rifting took place in the
Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145  Ma to 100.5 Ma. Geology Pro ...
. The pre-rift sequence of the basin comprises the Pennsylvanian Lolén Formation of the Ventana Group,Balarino, 2009, p.24 and the Sauce Grande, Piedra Azul,
Bonete Bonete is a municipality in Albacete, Castilla-La Mancha, Spain. It has inhabitants () and is located at a distance of from Albacete Albacete (, also , ; ar, ﭐَلبَسِيط, Al-Basīṭ) is a city and municipality in the Spanish aut ...
and Tunas Formations of the Pillahuincó Group, dating to the
Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...
.Balarino, 2009, p.22 During the late
Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...
, the Colorado Basin was located in the south polar region, causing a sequence of
glacial A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...
deposits in the basin. These deposits were mostly sourced from the African basin, the
Karoo The Karoo ( ; from the Afrikaans borrowing of the South Khoekhoe !Orakobab or Khoemana word ''ǃ’Aukarob'' "Hardveld") is a semi-desert natural region of South Africa. No exact definition of what constitutes the Karoo is available, so its ext ...
and
Kalahari Basin The Kalahari Basin, also known as the Kalahari Depression, Okavango Basin or the Makgadikgadi basin, is an endorheic basin and large lowland area covering approximately 725,293 km2 covering most of Botswana and Namibia, as well as parts of Angol ...
s. The Early Permian sediments are characterized by the presence of
diamictite Diamictite (; from Ancient Greek ''δια'' (dia-): ''through'' and ''µεικτός'' (meiktós): ''mixed'') is a type of lithified sedimentary rock that consists of nonsorted to poorly sorted terrigenous sediment containing particles that ra ...
s. A transgression in the Permian led to the deposition of the Piedra Azul Formation.Balarino, 2009, p.23 The succession contains several hiatuses, dating to the
Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
and
Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...
,
Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0.9 M ...
and
Paleogene The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...
.ENARSA, s.a., p.4 The early
Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...
succession is missing, and the main rifting phase happened in the
Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded ...
and
Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), a ...
, around 120 million years ago, represented in the Fortín Formation.Barredo & Stinco, 2010, p.52 The post-rift sag stage dates to the early
Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
leading to the deposition of the
alluvial Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluv ...
and
fluvial In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluviog ...
sediments of the Colorado Formation. The drift stage is represented by the Pedro Luro Formation. The later Cenozoic succession is characteristic of a terrestrial
passive margin A passive margin is the transition between oceanic and continental lithosphere that is not an active plate margin. A passive margin forms by sedimentation above an ancient rift, now marked by transitional lithosphere. Continental rifting creat ...
setting and comprises the
Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...
Elvira Elvira is a female given name. First recorded in medieval Spain, it is likely of Germanic (Gothic) origin. Elvira may refer to: People Nobility * Elvira Menéndez (died 921), daughter of Hermenegildo Gutiérrez and wife of Ordoño II of León ...
,
Middle Miocene The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene. The sub-epoch lasted from 15.97 ± 0.05 Ma to 11.608 ± 0.005 Ma (million y ...
Barranca Final Formation,Geologic Map Hojas 3963-III & IV, 2009, p.39 and the Middle to Late Miocene Gran Bajo de Gualicho Formation.Reichler, 2010, p.192 This formation in most of the basin is overlain by the Río Negro Formation.Reichler, 2010, p.183 The Late Miocene succession in the westernmost area of the basin is represented by the Arroyo Chasicó and eolian
Cerro Azul Formation The Cerro Azul Formation ( es, Formación Cerro Azul), in the Buenos Aires Province also described as Epecuén Formation, is a geological formation of Late Miocene (Tortonian, or Huayquerian in the SALMA classification) age in the Colorado Basin ...
s,Visconti et al., 2010, p.259 cropping out in the northern onshore part of the basin.Geologic Map Hojas 3963-III & IV, 2009, p.5 This sequence is covered by the
Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...
to
Early Pliocene Early may refer to: History * The beginning or oldest part of a defined historical period, as opposed to middle or late periods, e.g.: ** Early Christianity ** Early modern Europe Places in the United States * Early, Iowa * Early, Texas * Early ...
eolian and
fluvial In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluviog ...
Río Negro Formation,Pérez, 2010, p.7Geologic Map Hojas 3963-III & IV, 2009, p.8 outcropping in a thin band along the eponymous river.


Stratigraphy


Paleontological significance

The Miocene formations cropping out onshore have provided a rich
mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
fauna. The Arroyo Chasicó Formation is the defining formation for the
Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...
Chasicoan The Chasicoan ( es, Chasiquense or es, Chasicoense) age is a period of geologic time from 10–9 Ma within the Late Miocene epoch of the Neogene, used more specifically within the SALMA classification in South America. It follows the Mayoan and ...
South American land mammal age The South American land mammal ages (SALMA) establish a geologic timescale for prehistoric South American fauna beginning 64.5 Mya (unit), Ma during the Paleocene and continuing through to the Late Pleistocene (0.011 Ma). These periods are referre ...
, ranging from 10 to 9 million years ago.Chasicoan
at
Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...
.org
The formation contains many mammal species, birds and reptiles.Arroyo Chasicó
at
Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...
.org
The Cerro Azul Formation contains fossils of the
rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...
s '' Chasichimys bonaerense'',Verzi et al., 2008 '' Neocavia pampeana'',Madozzo Jaén et al., 2018, p.250 '' Reigechimys plesiodon'' and ''R. simplex'',Sostillo et al., 2014 the
armadillo Armadillos (meaning "little armored ones" in Spanish) are New World placental mammals in the order Cingulata. The Chlamyphoridae and Dasypodidae are the only surviving families in the order, which is part of the superorder Xenarthra, along wi ...
s '' Chasicotatus ameghinoi'', and '' Macrochorobates scalabrinii'', and the
opossum Opossums () are members of the marsupial order Didelphimorphia () endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 93 species in 18 genera. Opossums originated in South America and entered North ...
'' Zygolestes tatei'',Goin et al., 2000, p.108 among other mammals. The Río Negro Formation has provided fossils of the
glyptodont Glyptodonts are an extinct subfamily of large, heavily armoured armadillos. They arose in South America around 48 million years ago and spread to southern North America after the continents became connected several million years ago. The best-kn ...
'' Plohophorus figuratus''.Punta Bermeja
at
Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...
.org
The marine Gran Bajo de Gualicho Formation contains many
bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...
,
gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...
and
echinoid Sea urchins () are spine (zoology), spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard s ...
fossils,Reichler, 2010, pp.191-192 and the
cetacea Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...
n '' Preaulophyseter gualichensis''.Buono, 2013, p.36 The Eocene succession in boreholes of the basin has provided many species of
dinoflagellate The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...
s,Daners et al., 2016, p.293 and in the Permian sequence 131 species of spores, algae, funghi and
pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...
were registered.Balarino, 2012, p.343


Petroleum exploration

Contrary to other Southern Atlantic marginal basins, as the
Golfo San Jorge The San Jorge Gulf (Golfo San Jorge; Spanish for ''Gulf of St. George'') is a bay in southern Patagonia, Argentina. It is an ocean basin opening to the Atlantic. Its shoreline spans Chubut and Santa Cruz province. The gulf measures approximatel ...
and Austral Basins to the south, and
Santos Basin The Santos Basin ( pt, Bacia de Santos) is an approximately large mostly offshore sedimentary basin. It is located in the south Atlantic Ocean, some southeast of Santos, Brazil. The basin is one of the Brazilian basins to have resulted from th ...
of Brazil to the north, the Colorado Basin is not producing hydrocarbons. The first wells in the northern onshore part of the basin were drilled in 1946 (Pedro Luro-1) and 1948 (Ombucta-1) by
YPF YPF S.A. (, formerly ; English: "Fiscal Oilfields") is a vertically integrated, majority state-owned Argentine energy company, engaged in oil and gas exploration and production, and the transportation, refining, and marketing of gas and petr ...
. Another phase of onshore exploration happened in the 1960s, with seven wells drilled by
Shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard ou ...
.Rossello, 2016, p.175 Offshore drilling started in 1970 by
Hunt Oil Hunt Oil Co. is an independent oil and gas company headquartered in Dallas, Texas. It conducts its main oil production activities in the United States, Canada and, as of 1984, in Yemen. In the past, the company was owned by american oil tycoon ...
and after seismic acquisition in the 1970s by YPF,ENARSA, s.a., p.8 some wells were drilled in 1977 by the same company. Renewed exploration started in the mid-1990s with several wells drilled by Union Texas and Shell.ENARSA, s.a., p.5 The offshore Cruz del Sur x-1 well provided oil shows of 39°
API An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software Interface (computing), interface, offering a service to other pieces of software. A document or standa ...
.Pucci, 2006, p.18


See also

*
Pelotas Basin The Pelotas Basin ( pt, Bacia de Pelotas, es, Cuenca de Pelotas) is a mostly offshore sedimentary basin of approximately in the South Atlantic, administratively part of the southern states Santa Catarina and Rio Grande do Sul of Brazil and the ...
*
Cañadón Asfalto Basin The Cañadón Asfalto Basin ( es, Cuenca de Cañadón Asfalto) is an irregularly shaped sedimentary basin located in north-central Patagonia, Argentina. The basin stretches from and partly covers the North Patagonian Massif in the north, a high for ...
*
Golfo San Jorge Basin The Golfo San Jorge Basin ( es, Cuenca del Golfo San Jorge) is a hydrocarbon-rich sedimentary basin located in eastern Patagonia, Argentina. The basin covers the entire San Jorge Gulf and an inland area west of it, having one half located in Santa ...
* Austral Basin


References


Bibliography

;General * * * * * * * ;Geologic maps * * ;Arroyo Chasicó Formation * * * * ;Cerro Azul Formation * * * * * * ;Gran Bajo del Gualicho Formation * * ;Río Negro Formation * {{Sedimentary basins of Argentina Rift basins Passive margins Mesozoic rifts and grabens Sedimentary basins of Argentina Geology of Buenos Aires Province Geology of Río Negro Province Geology of Patagonia Geology of the Atlantic Ocean