The Queen Charlotte Basin is a structural basin mostly beneath the continental shelf offshore, between Haida Gwaii, Vancouver Island, and the British Columbia mainland, roughly coincident with the physiographic region named the Hecate Depression. [1]
The term Queen Charlotte Basin normally refers to the Cenozoic rocks, but these are underlain by what seems to be a thick Mesozoic succession. The Queen Charlotte Basin was formed by periods of extension, including thinning and volcanism during the mid-Cenozoic era. The large Cenozoic plutons that magnetic data suggest exist in the southeastern part of the Queen Charlotte Basin seem to be related to the Anahim hotspot.
Renewed interest in western Canadian shelf basins results from widespread expectations that the long-standing government moratorium on offshore exploration there may soon be lifted. The best oil prospects seem to exist in Cretaceous reservoirs in the southwestern part of the Queen Charlotte Basin, in western Queen Charlotte Sound.
With widespread oil seeps from rocks of all ages, two dozen wells were drilled in the Queen Charlotte and Tofino areas before the 1970s; many land areas were mapped in the 1980s and 1990s. However, Vancouver Island and Haida Gwaii mostly lack caprock. Hecate Strait seems to lack adequate source and reservoir rocks, and the offshore wells did not significantly test the Mesozoic horizons. Rocks on the mainland are crystalline. The Tofino, Winona, Georgia and Juan de Fuca basin lack significant known source rocks. By contrast, southwestern Queen Charlotte Basin seems to contain a stack of source, reservoir and caprock strata, largely at oil-window burial depths, as well as large block-fault trap structures.
While some workers (e.g., Lyatsky and Haggart, 1993; Lyatsky, 2006) regard the Mesozoic horizons to be the primary oil-exploration targets, others (e.g., Dietrich, 1995; Hannigan et al., 2001) focus more on the overlying Cenozoic rocks. Rohr and Dietrich (1992) considered the Queen Charlotte Basin to have formed largely by strike-slip movements in the Cenozoic. On the other hand, Lyatsky (1993, 2006) considered significant strike-slip movements to be impossible in this basin since at least the Late Oligocene, based on kinematic indicators and cross-cutting relationships of major faults and dated dikes; instead, he viewed the basin's Cenozoic evolution to be a product of reactivation of older networks of block-bounding faults.
Economic basement in the Queen Charlotte Basin area is massive, thick Upper Triassic flood basalts, underlain onshore by partly metamorphosed older rocks. Above, high-quality source rocks exist in the ~1,000 metres (0.62 mi)-thick Upper Triassic-Lower Jurassic assemblage, with oil-prone Type I and II kerogen and TOC (total organic carbon) up to 11%. Geochemical evidence suggests these rocks provided most of the basin's oil, and a major pulse of oil generation and migration was in the Cenozoic. The overlying Upper Jurassic-Upper Cretaceous clastic succession, ~3,000 metres (1.9 mi) thick, has negligible source potential but contains high-quality reservoirs with largely secondary porosity of ~15% or more. Above, mostly offshore, lie Cenozoic mudstone, sandstone and volcanic deposits, up to ~6,000 metres (3.7 mi) thick in some fault-bounded depocenters.
The Cenozoic deposits have gas-prone Type III and II kerogen, with up to 2.5% TOC locally. However, clay products of feldspar decomposition greatly degrade their permeability, especially at basal levels. Reservoir-quality sandstone facies are found largely near the top of this unit, where migration routes from below and the seal above may be inadequate. The Cenozoic deposits thus seem to be predominantly caprock, perhaps with some secondary exploration targets.
Stratigraphic and sedimentological studies indicate the Triassic-Jurassic source rocks were deposited in a broad shelfal basin encompassing this entire region and beyond. However, the Cretaceous basin was confined to western Haida Gwaii and northwestern Vancouver Island, with uplands to the east shedding detritus. Western Queen Charlotte Sound was probably part of the same Cretaceous basin, while eastern Queen Charlotte Sound and Hecate Strait largely lost their pre-existing source rocks and received few, non-marine, Cretaceous deposits. Cenozoic caprock, with thickness variable block to block, then blanketed Hecate Strait and Queen Charlotte Sound.
Western Queen Charlotte Sound should thus contain a favourable source-reservoir-seal stack. Gravity data also indicate a great thickness of undrilled low-density (sedimentary?) rocks is present beneath western Queen Charlotte Sound but not elsewhere in the Queen Charlotte Basin.
Caprock-breaching faults are sparser in Queen Charlotte Sound than in northern parts of the basin; the Queen Charlotte Basin is not overpressured. Regional geological and geophysical correlations suggest the major Mesozoic block-fault networks were reactivated in the Cenozoic. Seismic and gravity data show the fault-bounded Cenozoic depocenters and raised blocks to be comparatively broad in western Queen Charlotte Sound.
The caveats are several. Cretaceous rocks, deposited near their provenance areas, tend to be petrologically immature, and secondary porosity in them may be hard to predict. Buried source rocks beneath the deepest depocenters may be overmature. Some traps may be breached by Neogene faults: one offshore well encountered oil staining, suggesting oil passed through these Cenozoic rocks and escaped. A major influence on local hydrocarbon-maturation levels on Haida Gwaii is proximity to the mostly Jurassic and Cenozoic igneous plutons. Similar potential-field anomalies suggest massive igneous bodies may be present beneath eastern Queen Charlotte Sound, and correlations with mainland igneous suites of the Anahim Volcanic Belt put their age at Miocene. The pluton-related(?) magnetic anomalies do not seem to significantly extent into western Queen Charlotte Sound.
The Maracaibo Basin, also known as Lake Maracaibo natural region, Lake Maracaibo depression or Lake Maracaibo Lowlands, is a foreland basin and one of the eight natural regions of Venezuela, found in the northwestern corner of Venezuela in South America. Covering over 36,657 square km, it is a hydrocarbon-rich region that has produced over 30 billion bbl of oil with an estimated 44 billion bbl yet to be recovered. The basin is characterized by a large shallow tidal estuary, Lake Maracaibo, located near its center. The Maracaibo basin has a complex tectonic history that dates back to the Jurassic period with multiple evolution stages. Despite its complexity, these major tectonic stages are well preserved within its stratigraphy. This makes The Maracaibo basin one of the most valuable basins for reconstructing South America's early tectonic history.
The Perth Basin is a thick, elongated sedimentary basin in Western Australia. It lies beneath the Swan Coastal Plain west of the Darling Scarp, representing the western limit of the much older Yilgarn Craton, and extends further west offshore. Cities and towns including Perth, Busselton, Bunbury, Mandurah and Geraldton are built over the Perth Basin.
Texas contains a wide variety of geologic settings. The state's stratigraphy has been largely influenced by marine transgressive-regressive cycles during the Phanerozoic, with a lesser but still significant contribution from late Cenozoic tectonic activity, as well as the remnants of a Paleozoic mountain range.
The Queen Charlotte Fault is an active transform fault that marks the boundary of the North American plate and the Pacific plate. It is Canada's right-lateral strike-slip equivalent to the San Andreas Fault to the south in California. The Queen Charlotte Fault forms a triple junction south with the Cascadia subduction zone and the Explorer Ridge. The Queen Charlotte Fault (QCF) forms a transpressional plate boundary, and is as active as other major transform fault systems in terms of slip rates and seismogenic potential. It sustains the highest known deformation rates among continental or continent-ocean transform systems globally, accommodating greater than 50mm/yr dextral offset. The entire approximately 900 km offshore length has ruptured in seven greater than magnitude 7 events during the last century, making the cumulative historical seismic moment release higher than any other modern transform plate boundary system.
The Anahim hotspot is a hypothesized hotspot in the Central Interior of British Columbia, Canada. It has been proposed as the candidate source for volcanism in the Anahim Volcanic Belt, a 300 kilometres long chain of volcanoes and other magmatic features that have undergone erosion. This chain extends from the community of Bella Bella in the west to near the small city of Quesnel in the east. While most volcanoes are created by geological activity at tectonic plate boundaries, the Anahim hotspot is located hundreds of kilometres away from the nearest plate boundary.
Safaniya Oil Field, operated and owned by Saudi Aramco, is the largest offshore oil field in the world. It is located about 265 kilometres (165 mi) north of the company headquarters in Dhahran on the coast of the Persian Gulf, Saudi Arabia. Measuring 50 by 15 kilometres, the field has a producing capability of more than 1.2 million barrels per day.
The Jeanne d'Arc Basin is an offshore sedimentary basin located about 340 kilometres to the basin centre, east-southeast of St. John's, Newfoundland and Labrador. This basin formed in response to the large scale plate tectonic forces that ripped apart the super-continent Pangea and also led to sea-floor spreading in the North Atlantic Ocean. This basin is one of a series of rift basins that are located on the broad, shallow promontory of continental crust known as the Grand Banks of Newfoundland off Canada's east coast. The basin was named after a purported 20 metres shoal labelled as "Ste. Jeanne d'Arc" on out-dated bathymetric charts and which was once thought to represent a local exposure of basement rocks similar to the Virgin Rocks.
The Columbus Basin is a foreland basin located off the south eastern coast of Trinidad within the East Venezuela Basin (EVB). Due to the intensive deformation occurring along the Caribbean and South American plates in this region, the basin has a unique structural and stratigraphic relationship. The Columbus Basin has been a prime area for hydrocarbon exploration and production as its structures, sediments and burial history provide ideal conditions for generation and storage of hydrocarbon reserves. The Columbus Basin serves as a depocenter for the Orinoco River delta, where it is infilled with 15 km of fluvio-deltaic sediment. The area has also been extensively deformed by series of north west to southeast normal faults and northeast to southwest trending anticline structures.
The North Sea basin is located in northern Europe and lies between the United Kingdom, and Norway just north of The Netherlands and can be divided into many sub-basins. The Southern North Sea basin is the largest gas producing basin in the UK continental shelf, with production coming from the lower Permian sandstones which are sealed by the upper Zechstein salt. The evolution of the North Sea basin occurred through multiple stages throughout the geologic timeline. First the creation of the Sub-Cambrian peneplain, followed by the Caledonian Orogeny in the late Silurian and early Devonian. Rift phases occurred in the late Paleozoic and early Mesozoic which allowed the opening of the northeastern Atlantic. Differential uplift occurred in the late Paleogene and Neogene. The geology of the Southern North Sea basin has a complex history of basinal subsidence that had occurred in the Paleozoic, Mesozoic, and Cenozoic. Uplift events occurred which were then followed by crustal extension which allowed rocks to become folded and faulted late in the Paleozoic. Tectonic movements allowed for halokinesis to occur with more uplift in the Mesozoic followed by a major phase of inversion occurred in the Cenozoic affecting many basins in northwestern Europe. The overall saucer-shaped geometry of the southern North Sea Basin indicates that the major faults have not been actively controlling sediment distribution.
The Tarfaya Basin is a structural basin located in southern Morocco that extends westward into the Moroccan territorial waters in the Atlantic Ocean. The basin is named for the city of Tarfaya located near the border of Western Sahara, a region governed by the Kingdom of Morocco. The Canary Islands form the western edge of the basin and lie approximately 100 km to the west.
The Delta Field is located offshore from Nigeria on Oil Mining Leases (OML) 49 and 95. This is located within the Niger Delta Basin and sits in 12 feet of water. In 1965, the Delta 1 well was completed and the Delta Field opened in 1968 for production.
The Bolivar Coastal Fields (BCF), also known as the Bolivar Coastal Complex, is located on the eastern margin of Lake Maracaibo, Venezuela. Bolivar Coastal Field is the largest oil field in South America with its 6,000-7,000 wells and forest of related derricks, stretches thirty-five miles along the north-east coast of Lake Maracaibo. They form the largest oil field outside of the Middle East and contain mostly heavy oil with a gravity less than 22 degrees API. Also known as the Eastern Coast Fields, Bolivar Coastal Oil Field consists of Tía Juana, Lagunillas, Bachaquero, Ceuta, Motatán, Barua and Ambrosio. The Bolivar Coast field lies in the Maracaibo dry forests ecoregion, which has been severely damaged by farming and ranching as well as oil exploitation. The oil field still plays an important role in production from the nation with approximately 2.6 million barrels of oil a day. It is important to note that the oil and gas industry refers to the Bolivar Coastal Complex as a single oilfield, in spite of the fact that the oilfield consists of many sub-fields as stated above.
The Wessex Basin is a petroleum-bearing geological area located along the southern coast of England and extending into the English Channel. The onshore part of the basin covers approximately 20,000 km2 and the area that encompasses the English Channel is of similar size. The basin is a rift basin that was created during the Permian to early Cretaceous in response to movement of the African plate relative to the Eurasian plate. In the late Cretaceous, and again in the Cenozoic, the basin was inverted as a distant effect of the Alpine orogeny. The basin is usually divided into 3 main sub-basins including the Winterborne-Kingston Trough, Channel Basin, and Vale of Pewsey Basin. The area is also rich in hydrocarbons with several offshore wells in the area. With the large interest in the hydrocarbon exploration of the area, data became more readily available, which improved the understanding of the type of inversion tectonics that characterize this basin.
The geology of Somaliland is very closely related to the geology of Somalia. Somaliland is a de facto independent country within the boundaries that the international community recognizes as Somalia. Because it encompasses the former territory of British Somaliland, the region is historically better researched than former Italian Somaliland. Somaliland is built on more than 700 million year old igneous and metamorphic crystalline basement rock.. These ancient units are covered in thick layers of sedimentary rock formed in the last 200 million years and influenced by the rifting apart of the Somali Plate and the Arabian Plate.
The geology of Alaska includes Precambrian igneous and metamorphic rocks formed in offshore terranes and added to the western margin of North America from the Paleozoic through modern times. The region was submerged for much of the Paleozoic and Mesozoic and formed extensive oil and gas reserves due to tectonic activity in the Arctic Ocean. Alaska was largely ice free during the Pleistocene, allowing humans to migrate into the Americas.
The geology of Montana includes thick sequences of Paleozoic, Mesozoic and Cenozoic sedimentary rocks overlying ancient Archean and Proterozoic crystalline basement rock. Eastern Montana has considerable oil and gas resources, while the uplifted Rocky Mountains in the west, which resulted from the Laramide orogeny and other tectonic events have locations with metal ore.
The geology of Denmark includes 12 kilometers of unmetamorphosed sediments lying atop the Precambrian Fennoscandian Shield, the Norwegian-Scottish Caledonides and buried North German-Polish Caledonides. The stable Fennoscandian Shield formed from 1.45 billion years ago to 850 million years ago in the Proterozoic. The Fennoscandian Border Zone is a large fault, bounding the deep basement rock of the Danish Basin—a trough between the Border Zone and the Ringkøbing-Fyn High. The Sorgenfrei-Tornquist Zone is a fault-bounded area displaying Cretaceous-Cenozoic inversion.
The geology of Venezuela includes ancient Precambrian igneous and metamorphic basement rocks, layered with sedimentary rocks from the Paleozoic and Mesozoic and thick geologically recent Cenozoic sediments with extensive oil and gas.
Kapuni is an onshore natural gas-condensate field located in the Taranaki Basin, a ~100,000 km2 partially-inverted rift basin on the Taranaki Peninsula in the North Island, New Zealand. Discovered in 1959 and brought into production in 1970, Kapuni remained New Zealand's only producing gas-condensate field until the offshore Maui gas field began production in 1979.
The geology of the Norwegian Sea began to form 60 million years ago in the early Cenozoic, as rifting led to the eruption of mafic oceanic crust, separating Scandinavia and Greenland. Together with the North Sea the Norwegian Sea has become highly researched since the 1960s with the discovery of oil and natural gas in thick offshore sediments on top of the Norwegian continental shelf.