Trans-Hudson orogen (blue) surrounded by the Wyoming Hearne-Rae and Superior cratons (pink) that constitute the central core of the North American craton (Laurentia). The Wyoming craton is located in the west-central United States -- more specifically in Montana, Wyoming, and parts of northern Utah. Rae craton is an Archean Craton located in northern Canada north of the Superior craton. Superior Craton (or Superior Province) forms the core of both the North American continent and the Canadian Shield. A craton ( Greek kratos / κρἀτος ( neut. "strength" is an old and stable part of the Continental crust that has survived Laurentia (also known as the North American craton) like all Craton land was created as continents moved about the surface of the Earth

The North American craton, also called Laurentia. Laurentia (also known as the North American craton) like all Craton land was created as continents moved about the surface of the Earth

Trans-Hudson orogen and the Wyoming, Superior and Hearne cratons

The Trans-Hudson orogeny, Trans-Hudsonian orogeny, Trans-Hudson orogen (THO), or Trans-Hudson Orogen Transect (THOT), (also referred to as the Trans-Hudsonian Suture Zone (THSZ) or Trans-Hudson suture), was the major mountain building (orogeny) event that formed the Precambrian Canadian Shield, the North American craton (also called Laurentia), and the forging of the initial North American continent. The Wyoming craton is located in the west-central United States -- more specifically in Montana, Wyoming, and parts of northern Utah. Superior Craton (or Superior Province) forms the core of both the North American continent and the Canadian Shield. A craton ( Greek kratos / κρἀτος ( neut. "strength" is an old and stable part of the Continental crust that has survived A mountain is a Landform that extends above the surrounding Terrain in a limited area with a peak Orogeny (Greek for "mountain generating" is the process of natural Mountain building and may be studied as a tectonic structural event as a geographical event and The Precambrian ( Pre-Cambrian) is an informal name for the supereon comprising the eons of the Geologic timescale that came before the current The Canadian Shield &mdash also called the Laurentian Plateau, or Bouclier Canadien (French &mdash is a large geological shield covered by Laurentia (also known as the North American craton) like all Craton land was created as continents moved about the surface of the Earth Laurentia (also known as the North American craton) like all Craton land was created as continents moved about the surface of the Earth A continent is one of several large Landmasses on Earth. They are generally identified by Convention rather than any strict criteria with seven regions It is the only Paleoproterozoic orogenic belt in North America, and the largest Paleoproterozoic orogenic belt in the world. The Paleoproterozoic (ˌpeɪlɪoʊˌproʊtərəˈzoʊɪk also spelled Palaeoproterozoic) is the first of the three sub-divisions ( eras) of the Orogeny (Greek for "mountain generating" is the process of natural Mountain building and may be studied as a tectonic structural event as a geographical event and It consists of a network of belts that were formed by Proterozoic crustal accretion and the collision of pre-existing Archean continents. In Geology, a crust is the outermost solid shell of a planet or moon Accretion is a process by which material is added to a Tectonic plate. A continent is one of several large Landmasses on Earth. They are generally identified by Convention rather than any strict criteria with seven regions The event occurred 2. 0-1. 8 billion years ago.

The Trans-Hudson orogen sutured together the Hearne-Rae, Superior, and Wyoming cratons to form the cratonic core of North America in a network of Paleoproterozoic orogenic belts. Rae craton is an Archean Craton located in northern Canada north of the Superior craton. Superior Craton (or Superior Province) forms the core of both the North American continent and the Canadian Shield. The Wyoming craton is located in the west-central United States -- more specifically in Montana, Wyoming, and parts of northern Utah. A craton ( Greek kratos / κρἀτος ( neut. "strength" is an old and stable part of the Continental crust that has survived These orogenic belts include the margins of at least nine independent microcontinents that were themselves sections of at least three former major supercontinents, including Laurasia, Pangaea and Kenorland (ca. For a topic outline on this subject see List of basic Australia topics. Laurasia (lɔˈreɪʃiə lɔˈreɪʒə was a Supercontinent that most recently existed as a part of the split of the Pangaean supercontinent in the late Mesozoic Pangaea, Pangæa or Pangea (pænˈdʒiːə from παν pan, meaning entire, and Γαῖα Gaea, meaning Earth in Kenorland was one of the earliest Supercontinents on Earth It is believed to have formed during the Neoarchaean Era ~2 2. 7 Ga), and contain parts of some of the oldest cratonic continental crust on Earth. Annum is one form of the Latin noun meaning Year, not a form normally used for derivatives in modern languages the accusative singular The continental crust is the layer of granitic, Sedimentary, and Metamorphic rocks which form the Continents and the areas of shallow seabed EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 These old cratonic blocks, along with accreted island arc terranes and intraoceanic deposits from earlier Proterozoic and Mesozoic oceans and seaways, were sutured together in the Trans-Hudson Oregon (THO) and resulted in extensive folding and thrust faulting along with metamorphism and hundreds of huge granitic intrusions. A volcanic arc is a chain of volcanic islands or Mountains formed by Plate tectonics as an oceanic Tectonic plate subducts under A terrane in Geology is a fragment of crustal material formed on or broken off from one Tectonic plate and accreted — " sutured " An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. The Mesozoic Era is one of three geologic eras of the Phanerozoic eon. A thrust fault is a type of fault, or break in the Earth's crust with resulting movement of each side against the other in which a lower stratigraphic position is pushed up Granite (ˈɡrænɪt is a common and widely occurring type of intrusive, Felsic, igneous rock. In Geology, an intrusion is a body of Igneous rock that has Crystallized from molten Magma below the surface of the Earth. ^[1]

The THO is a right-angled suture zone that extends eastward from Saskatchewan through collisional belts in the Churchill province, through northern Quebec, parts of Labrador and Baffin Island, and all the way to Greenland as the Rinkian belt and Nagssugtodidian Orogen. Saskatchewan (səˈskætʃəwən) is a prairie province in Canada, which has an area of 588276 Churchill craton is the northwest section of the Canadian Shield and stretches from southern Saskatchewan and Alberta to northern Nunavut. Quebec (kwɨˈbɛk Modern Labrador Just like its island neighbour Newfoundland early settlement in Labrador was tied to the sea as demonstrated by the Montagnais, Innu and Baffin Island (ᕿᑭᖅᑖᓗᒃ Qikiqtaaluk, Île de Baffin Old Norse: Helluland) in the territory of Nunavut is the largest member Greenland (Kalaallit Nunaat meaning "Land of the Greenlanders" Grønland is a self-governing Danish Province located between the Westward it goes across Hudson Bay through Saskatchewan and then extends 90 degrees south through eastern Montana and the western Dakotas, downward through eastern Wyoming and western Nebraska, and is then cut off by the Cheyenne belt - the northern edge of the Yavapai province (see Trans-Hudson Orogen map^[2] and the THOT Transect map^[3]. Montana ( is a state in the Western United States. One-third of the state in the western part contains numerous mountain ranges (approximately 77 named of the northern The Dakotas is a collective term used around the world that refers to the U The State of Wyoming ( is a sparsely populated state in the western region of the United States. Nebraska ( is a state located on the Great Plains of the Midwestern United States and To the south, the orogen contributed to the subsurface Phanerozoic strata in Montana and the Dakotas that created the Great Plains. The Phanerozoic (occasionally Phanaerozoic) Eon is the current eon in the Geologic timescale, and the one during which abundant animal life has existed The Great Plains are the broad expanse of Prairie and Steppe which lie east of the Rocky Mountains in the United States and Canada

Overview

The Trans-Hudson orogeny was the culminating event of the Paleoproterozoic Laurentian assembly, which occurred after the Wopmay orogeny (West of Hudson Bay, ca. 2. 1-1. 9 Ga. ). The Trans-Hudson orogeny resulted from the collision of the Superior craton of eastern Canada with the Hearne craton in northern Saskatchewan and the Wyoming craton of the western United States, with the Archaen microcontinent Sask craton trapped in the THO western interior. Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page Saskatchewan (səˈskætʃəwən) is a prairie province in Canada, which has an area of 588276 The United States of America —commonly referred to as the The northern edge of the THO is marked by an exposed continental collision zone on Baffin Island (Canada) that occurred between ca. Baffin Island (ᕿᑭᖅᑖᓗᒃ Qikiqtaaluk, Île de Baffin Old Norse: Helluland) in the territory of Nunavut is the largest member Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page 1. 85-1. 835 Ga. On Baffin Island, ca. 1. 845 Ga. crustal thickening occurred that was associated with accretion of an intra-oceanic arc terrane and subsequent regional metamorphic activity characterized by the growth of retrograde, upper amphibolite-facies assemblages that define a clockwise, decompressive P–T path (pressure-temperature) path. In Geology, a crust is the outermost solid shell of a planet or moon Metamorphism can be defined as the solid state recrystallisation of pre-existing rocks due to changes in heat and/or pressure and/or introduction of fluids i Amphibolite (æmˈfɪbəlaɪt is the name given to a rock consisting mainly of hornblende Amphibole, the use of the term being restricted however to Metamorphic The term " Facies " can also refer to distinctive Facial expressions associated with conditions such as Williams syndrome. In Physical chemistry, Mineralogy, and Materials science, a phase diagram is a type of graph used to show the equilibrium conditions Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Final mineral growth on Baffin Island occurred between 1. A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific 82-1. 81 Ga. and occurred as a progressive change from plate-margin to intraplate processes within an evolving convergent orogeny. ^[4] Collectively, these collisions resulted in a mountain range that rivaled the grandeur of the Himalayas. ^[1] Similar to the Himalayas, the Trans-Hudson orogeny was also the result of continent-continent collision along a suture zone. Only the roots of this mountain chain remain, but these can be seen in northeastern Saskatchewan and in the Black Hills of South Dakota. The Trans-Hudson orogeny and the consequent upheaval of the continental crust in the middle Proterozoic eon caused the area around the Great Lakes to become a flattened plain, which in turn led to the creation of the intercontinental basin and the interior and central plains of the United States (the Great Plains are the westernmost portion of North America's Interior Plains, which extend east to the Appalachian Plateau). The Laurentian Great Lakes are a chain of freshwater lakes located in eastern North America, on the Canada–United States border. The United States of America —commonly referred to as the The Great Plains are the broad expanse of Prairie and Steppe which lie east of the Rocky Mountains in the United States and Canada The Interior Plains is a vast physiographic region that spreads across the Laurentian craton of North America The Appalachian Plateau is the western part of the Appalachian mountains, stretching from New York to Georgia and Alabama.

The Black Hills of South Dakota is one of the few remaining exposed portions of the Trans-Hudson orogenic belt. The Black Hills ( Pahá Sápa in Lakota, Moˀȯhta-voˀhonáaeva in Cheyenne) are a small isolated Mountain range rising from the South Dakota ( is a state located in the Midwestern region of the United States of America. It is a huge, elliptically domed area in northwestern South Dakota and northeastern Wyoming about 125 miles long and 65 miles wide where the THO uplift caused erosion to remove the overlying cover of the Proterozoic marine sedimentary rocks and expose the granite and metamorphic rocks that formed the core of the dome. The peaks of the Black Hills are 3,000 to 4,000 feet above the surrounding plains, while Harney Peak - the highest point in South Dakota - has an altitude of 7,242 feet above sea level. ^[5] These central spires and peaks all are carved from granite and other igneous and metamorphic rocks that form the core of the uplift. The nature and timing of this portion of the THO event in southern Laurentia is poorly understood compared to the exposed northern segments in Canada. The Black Hills offer the only surface exposure of the deformed and metamorphosed belt of Paleoproterozoic continental margin rocks in the collisional zone between the Archean Wyoming and Superior provinces. Based on geophysical evidence, this zone has been broadly interpreted to be the southern extension of the THO that was later truncated by the ~1. 680 Ga. Central Plains orogen. ^[6]

Sequence of events

Marine evidence indicates that the area initially opened to form an ocean called the Manikewan Ocean. Faulting, sedimentary and igneous rocks all indicate that divergence formed a rift valley that continued to spread until it resulted in a passive margin in which there was no tectonic activity. Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock) Igneous rocks (etymology from Latin ignis, fire are rocks formed by solidification of cooled Magma (molten rock A rift valley is a linear-shaped lowland between highlands or mountain ranges created by the action of a geologic Rift or fault. Shallow marine deposits formed on the continental shelves, and oceanic crust formed on the margins of the continental cratons as the divergence continued. Oceanic crust is the part of Earth's Lithosphere that surfaces in the Ocean basins Eventually the divergence stopped, then reversed direction, and collision occurred between continental land masses. During the Wopmay orogeny, subduction occurred as oceanic crust of the Slave craton was subducted beneath an eastward moving continental plate. Slave craton is a relatively small Archean Craton (about 300000 km² located in the Northwest Territories of Canada. In Geology, a subduction zone is an area on Earth where two tectonic plates meet and move towards one another with one sliding underneath the other Likewise, during the Trans-Hudson orogeny, rifting at first separated the Superior craton from the rest of the continent. Then the Superior craton reversed its direction and the ocean basin began to close. A subduction zone formed as the oceanic crust of the Superior craton was subducted beneath the Hearne and Wyoming craton with the Sask craton in the middle. Volcanic arcs developed as the cratons collided, eventually resulting in the THO mountain building (orogeny). A volcanic arc is a chain of volcanic islands or Mountains formed by Plate tectonics as an oceanic Tectonic plate subducts under

During the opening and then closure of the Manikewan Ocean, the following sequence of events occurred:

• 1) Deposition of passive margin sequences, beginning at ca. 2. 16 Ga.
• 2) Ocean closure beginning at ca. 1. 92 Ga in the western THO, leading to the formation of the La Ronge/Lynn Lake, the Flin Flon Domain/Glennie island arcs, and the Pelican Thrust located between the two volcanic arc complexes and the Archaen Sask craton. La Ronge is a Community of about 3500 people in Northern Saskatchewan, Canada, 250 km north of Prince Albert. Lynn Lake is a small town in the northwest region of Manitoba, Canada, 1071 km from Winnipeg. Flin Flon (pop 5594 in 2006 census is a Canadian mining city and border city of Saskatchewan and Manitoba.
• 3) Beginning at about 1. 88 Ga, accretion of the La Ronge/Lynn Lake arcs to the Hearne craton margin and related deposition of an extensive molasse/foredeep sequence. Molasse refers to the Sandstones, Shales and conglomerates formed as terrestrial or shallow marine deposits in front of rising mountain chains This event was contemporaneous with intraoceanic accretion leading to the formation of the Flin Flon/Glennie accretionary complex.
• 4) Continental arc magmatism along the SE margin of the Churchill plate between 1. Magma (Plurals magmas and magmata) is molten rock that sometimes forms beneath the surface of the Earth (or any other Terrestrial planet 86 Ga and 1. 85 Ga.
• 5) Cessation of continental arc magmatism at about 1. 850 Ga, perhaps related to collision of the Flin Flon/Glennie complex (western THO) and Narsajuaq arc (Baffin segment), with the Churchill plate.
• 6) Opening of the Kissinew back-arc basin during the interval 1. Back-arc basins (or retro-arc basins are geologic features submarine basins associated with Island arcs and Subduction zones. 85-1. 84 Ga, with the Flin Flon complex now forming part of the active arc and Granville Lake Structural Zone forming part of the remnant arc. Granville Lake is a small community in Northern Manitoba. The community does not have all-weather road access rather the community relies on ice roads in the winter and the
• 7) Collision between the Sask Craton and Churchill Plate, beginning at ca. 1. 84 Ga, leading to the inversion of the Kisseynew basin and deposition of molasse deposits. In Structural geology inversion or basin inversion relates to the relative uplift of a Sedimentary basin or similar structure as a result of Crustal
• 8) Terminal collision involving the Superior craton, beginning at ca. 1. 83 Ga and ongoing until approximately 1. 77 Ga. (Corrigan, 2004). ). ^[7]
• 9) The final stages of continental collision where marked by 1. 84-1. 82 Ga. magma generation within the Kisseynew domain related to interaction between the Sask craton and the Flin Flon–Glennie complex, and a 1. The Flin Flon greenstone belt, also referred to as the Flin Flon-Snow Lake greenstone belt, is a Precambrian Greenstone belt located in the central area 82-1. 79 Ga. collision of the Rae and Superior cratons. ^[4] A decrease in subduction angle likely resulted from northward-directed subduction of more buoyant crust, with associated changes in thermal conditions leading to melting over a wide area. Ultimately subduction ceased, and the slab foundered into the mantle, potentially resulting in the generation of alkalic and potassic magmas within the Rae and Hearne cratons. ^[8]

Geographic areas

The Trans-Hudson Orogen is the only fully preserved Early Proterozoic orogenic belt in North America. It is a network of belts formed by Proterozoic crustal accretion and the collision of pre-existing Archean continents: the Hearne-Rae provinces to the northwest, the Superior Province to the southeast, and the Wyoming province to the southwest. ^[9] In the northern Saskatchewan and Manitoba provinces, the 500 km wide orogen includes four major lithotectonic zones:^[10]

• 1. Saskatchewan (səˈskætʃəwən) is a prairie province in Canada, which has an area of 588276 Manitoba (English ˌmænɨˈtoʊbə French /manitoba/ is a province of Canada, spanning 647797 square kilometres (250116  sq mi of North America a northwest hinterland zone (divided into smaller domains);
• 2. an Andean-type magmatic arc batholith;
• 3. an internal zone of juvenile Proterozoic crust;
• 4. a southeast foreland zone (with prominent, pervasive east-dipping seismic reflectors throughout the crust (not west-dipping as expected) where the orogen bounds the Superior Province). Seismology (from Greek grc σεισμός seismos, "earthquake" and grc -λογία -logia) is the scientific study of Earthquakes

Northwestern hinterland zone

The Northwestern hinterland zone is a complex tectonically deformed region that includes the Peter Lake, Wollaston, and Seal River domains, and other parts of the Cree Lake Zone, now included in Hearne Province.

Reindeer zone

The Reindeer zone to the north is a 500 km wide collage of Paleoproterozoic (1. 92-1. 83 Ga) arc volcanic rocks, plutons, volcanogenic sediments, and younger molasse, divisible into several lithostructural domains. Molasse refers to the Sandstones, Shales and conglomerates formed as terrestrial or shallow marine deposits in front of rising mountain chains Most of these rocks evolved in an oceanic to transitional, subduction-related arc setting, with increasing influence of Archean crustal components to the northwest. The zone overlies Archean basement exposed in structural window that are now recognized as the Sask craton.

Wathaman-Chipewyan batholith

The Wathaman-Chipewyan batholith is an Andean-type continental-margin, magmatic arc emplaced 1. A batholith (from Greek bathos, depth + lithos, rock is a large emplacement of Igneous intrusive (also called plutonic rock that forms 86-1. 85 Ga.

Glennie domain

The Glennie domain is in the western segment of the orogen in the internal zone in Saskatchewan, and consists mostly of 2. 4–2. 5 Ga felsic plutonic rocks enveloped by the Nistowiak Thrust. Felsic is a term used in Geology to refer to Silicate minerals, Magma, and rocks which are enriched in the lighter elements such as Silicon The Nistowiak Thrust is a folded, 1–2 km thick, upper amphibolite facies mylonite zone formed during emplacement of the Flin Flon–Glennie Complex across the ancient Saskatchewan continental area. Amphibolite (æmˈfɪbəlaɪt is the name given to a rock consisting mainly of hornblende Amphibole, the use of the term being restricted however to Metamorphic The term " Facies " can also refer to distinctive Facial expressions associated with conditions such as Williams syndrome. Mylonite is a fine-grained compact rock produced by dynamic crystallization of the constituent minerals resulting in a It correlates to the Pelican Thrust, which envelops Archaean basement windows in the Hanson Lake Block 100 km to the east. There is an internal high strain zone within the overlying nappe pile called the Guncoat Thrust that is composed primarily of mylonitized porphyroclastic pelitic and psammitic migmatites. In Geology, a nappe is a large sheetlike body of rock that has been moved more than 2 km (1 Mylonite is a fine-grained compact rock produced by dynamic crystallization of the constituent minerals resulting in a Pelite ( Greek Pelos, Clay is a descriptive name for a Clastic rock with a grain size of less than 1/16mm (originally sand or silt Examples include Migmatite is a rock at the frontier between igneous and Metamorphic rocks They can also be known as diatexite. U-Pb geochronological results suggest 1. Uranium-lead is one of the oldest and most refined Radiometric dating schemes with a routine age range of about 1 million years to over 4 In the Natural sciences under the umbrella of Natural history, Geochronology is the Science of determining the absolute age of rocks, Fossils 889–1. 837 Ga calc-alkaline plutonism, thrust stacking, peak metamorphism and associated 1. Calc-alkaline and calc-alkalic are equivalent terms applied to groups of Igneous rocks that commonly occur together and that have compositions related by the characteristic 837-1. 809 Ga anatexis, isotopic closure of titanite at 1. Anatexis in Geology, refers to the differential or partial melting of rocks, especially in the forming of Metamorphic rocks such as Migmatites Titanite or sphene is a Calcium Titanium nesosilicate Mineral, Ca[[titanium Ti]] Si[[oxygen O]]5 790–1. 772 Ga, and intrusion of late granitic rocks at 1. In Geology, an intrusion is a body of Igneous rock that has Crystallized from molten Magma below the surface of the Earth. 770–1. 762 Ga. This is in agreement with ages from the Hanson Lake Block, and La Ronge, Kisseynew, and Flin‐Flon domains in Saskatchewan and Manitoba, and from the Ungava‐Baffin portion of Trans-Hudson Orogen, suggesting broadly synchronous thermotectonic processes along a strike length of 2,000 km. This suggests that the Saskatchewan continental section rifted from the Superior and/or Hearne Provinces ca. 2. 1 Ga and that the Maniwekan Ocean developed between the Rae-Hearne and Superior cratons as their plate motions opened and closed. ^[11] The consequent crustal formations around parts of the arc-granitoid Glennie domain surface features are penetrated by Archean basement "windows". Granite (ˈɡrænɪt is a common and widely occurring type of intrusive, Felsic, igneous rock. These Archaean basement "windows" is what identifies the previously unknown Archean microcontinent, now called the Sask craton.

Kisseynew back-arc basin

The Kisseynew back-arc basin (Kisseynew domain) is a metasedimentary gneiss belt that is one of the most extensive tectonic segments of the Paleoproterozoic Trans-Hudson orogen in north-central Canada. Back-arc basins (or retro-arc basins are geologic features submarine basins associated with Island arcs and Subduction zones. Gneiss (ˈnaɪs is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from preexisting formations that were originally This article discusses the geologic usage for the philosophical or architectural usage see Architectonics ' Or see Plate tectonics. It comprises turbidites (horizontally spreadout sediments deposited from a swiftly-moving downward-flowing current, such as from an existing continental slope) and continental sandstones, both of which are interlayered with volcanic rocks and intruded plutons. Turbidite Geological formations have their origins in Turbidity current deposits, which are deposits from a form of underwater Avalanche that Sandstone is a Sedimentary rock composed mainly of Sand -size Mineral or rock grains. In Geology, an intrusion is a body of Igneous rock that has Crystallized from molten Magma below the surface of the Earth. A pluton in Geology is an Intrusive Igneous rock body that crystallized from a Magma slowly cooling below the surface of the Earth The dating of the encompanying detrital zircons and the dates of the intruded crosscutting plutons constrain the dates of the turbidite sedimentation to 1. Detritus (adjective detrital) is a geological term used to describe particles of rock derived from pre-existing rock through processes of Weathering and Zircon is a Mineral belonging to the group of nesosilicates. Its chemical name is Zirconium silicate and its corresponding chemical formula is 855-1. 841 Ga. These turbidites are interpreted to have been deposited in a back-arc basin behind a retreating subduction boundary. This postdates the early deformation and metamorphism of the Trans-Hudson orogeny associated with arc-arc and arc-continent collisions. Metamorphism can be defined as the solid state recrystallisation of pre-existing rocks due to changes in heat and/or pressure and/or introduction of fluids i The turbidites are deposited in a back-arc basin behind a retreating subduction boundary. The Kisseynew domain and its southern flank are marked by 1. 84-1. 83 Ga magmatic rocks related to subduction of back-arc basin oceanic crust. Magma (Plurals magmas and magmata) is molten rock that sometimes forms beneath the surface of the Earth (or any other Terrestrial planet Collapse of the Kisseynew "basin" by ductile fold-and-thrust deformation began during 1. Ductility is a mechanical property used to describe the extent to which materials can be deformed plastically or "stretched" into "wires" without 84-1. 83 Ga magmatism and continued through peak metamorphism at ca. 1. 820-1. 805 Ga. The result was that the high-grade core of the Kisseynew domain was structurally emplaced over adjacent low-grade terranes. The extensive high-temperature/low-pressure metamorphism explains the thickening and thermal relaxation of the basin-fill rocks that are marked by a 1. 84-1. 83 Ga elevated geotherm magmatism. In Geology, geothermal refers to heat sources within the planet ^[12]

Reed Lake belt

The Reed Lake belt is part of the internal zone of the Trans-Hudson Orogen and consists of Paleoproterozoic volcanic, plutonic and minor sedimentary rocks. The exposed portion of the belt is 250 km long by 75 km wide. Although it has an apparent easterly trend, this is an artifact of the belt's tectonic contact with gneissic metasedimentary, metavolcanic and plutonic rocks to the north (Kisseynew Domain) and the east-trending trace of Phanerozoic platformal cover rocks to the south. In reality the Reed Lake greenstone belt extends hundreds of kilometres to the south-southwest beneath a thin, geophysically transparent Phanerozoic cover. Greenstone belts are zones of variably metamorphosed Mafic to Ultramafic Volcanic sequences with associated Sedimentary rocks that The Phanerozoic (occasionally Phanaerozoic) Eon is the current eon in the Geologic timescale, and the one during which abundant animal life has existed To the north the Reed Lake Belt is tectonically overthrust by younger metasedimentary rocks of the Kisseynew domain and by nappes of metavolcanic rocks of the same age. In Geology, a nappe is a large sheetlike body of rock that has been moved more than 2 km (1 In fact, the entire Reed Lake-Snow Lake domain is an imbricated thrust wedge carried on a lower detachment zone overridden by high grade Kisseynew gneisses.

The NATMAP Shield Margin Project and LITHOPROBE Trans-Hudson Orogen Transect have shown that the Reed Lake greenstone belt (and contained VMS deposits) is only one of three components in a northeast-dipping stack that was juxtaposed during the 1. 84-1. 80 Ga collisional deformations.

1) at the lowest structural level (exposed in the Pelican window): metaplutonic rocks and paragneisses (3. 20-2. 40 Ga) of the "Sask craton". 2) at intermediate structural levels: Reed Lake belt (now defined to include the Attitti block and Paleoproterozoic rocks in the Hanson Lake block) and Glennie Domain (together comprising the "Reed Lake-Glennie complex. " 3) at the highest structural levels: marine turbidites (Burntwood Group; 1. 85-1. 84 Ga) and partly coeval distal facies of alluvial-fluvial sandstones (Missi Group) in the Kisseynew Domain.

The Reed Lake Belt is usually described by two stratigraphic groups: the 1. 92-1. 87 Ga. Amisk Group volcanic-plutonic rocks, and the Missi Group continental sedimentary rocks. The Reed Lake Belt is a collage of distinct tectonostratigraphic assemblages composed of structurally juxtaposed volcanic and sedimentary rock that were emplaced in a variety of tectonic environments. The major 1. 92-1. 88 Ga components include significant juvenile arc and juvenile ocean-floor rocks, and minor ocean plateau/ocean island basalt. The juvenile arc assemblage comprises tholeiitic, calc-alkaline and lesser shoshonitic and boninitic rocks similar in major and trace element geochemistry to modern intraoceanic arcs. Tholeiitic basalt is an Igneous rock, a type of Basalt. Like all basalt the rock type is dominated by Clinopyroxene plus Plagioclase, with minor Calc-alkaline and calc-alkalic are equivalent terms applied to groups of Igneous rocks that commonly occur together and that have compositions related by the characteristic Boninite is a Mafic Extrusive rock high in both Magnesium and silica formed in fore-arc environments typically during the early stages Ocean-floor basalt sequences are exclusively tholeiitic, and are geochemically similar to modern N- and E-type MORBs erupted in back-arc basins. Evolved arc assemblages and Archean crustal slices are present within the Reed Lake Belt as minor components. Collectively, these tectonostratigraphic assemblages were juxtaposed in an accretionary complex at Ca. 1. 88-1. 87 Ga. as a result of arc-arc collisions. The collage was a basement to a 1. 87-1. 83 Ga post-accretion arc magmatism that was expressed as voluminous calc-alkaline plutons and rarely preserved calc-alkaline to alkaline volcanic rocks. Unroofing of this accretionary collage, and the deposition of continental alluvial-fluvial sedimentary rocks (Missi Group) and marine turbidites (Burntwood Group) occurred Ca. 1. 85-1. 84 Ga, coeval with the waning stages of post-accretion arc magmatism. The sedimentary suites were imbricated with volcanic assemblages in the eastern Reed Lake Belt during 1. 85-1. 82 Ga juxtaposition of the supracrustal rocks along pre-peak metamorphic structures. Post ca. 1. 83 Ga structures formed the present southwest-verging fold style at the northeastern end of the Reed Lake Belt. Emplacement of voluminous granitoid plutons and regional deformation related to the occurred during the Ca. 1. 8 Ga Hudsonian Orogeny. ^[8]

Flin Flon domain

The Flin Flon domain is in the center of the Trans-Hudson Suture Zone and extends over the border of the Manitoba-Saskatchewan segment east and west. It is west of the Superior craton, south of the Kisseynew Domain, and east of the Glennie Domain.

Sask craton

The Sask craton is exposed in two structural windows in the western Flin Flon and Glennie domains to a depth of at least 25 km over an area of at least 100,000 km². The presence of the Sask craton may have arrested the complete collision of the Superior and Hearne cratons and allowed the preservation of a significant amount of juvenile magmatic and sedimentary terranes in allochthons within the internides (Reindeer Zone). The sole of these juvenile terranes is the Pelican Thrust, which is seismically highly recognizable and is considered to be a well-defined orogen-scale discontinuity that facilitated underthrusting of the Archean Sask craton below Paleoproterozoic juvenile rocks from before 1. 825 Ga until after 1. 805 Ga. This led to thickening of the sedimentary rocks in the overlying Kisseynew Domain and the development of localized high temperature–low pressure peak-metamorphic conditions coeval with melting and advection of heat within this part of the orogen. The Sask craton was initially identified by seismic reflection along the Glennie and western Flin Flon domains and is now known to extend at depth northward and eastward well into Manitoba. Based on MT measurements, the Sask craton is resistive relative to the Paleoproterozoic volcano-sedimentary belts. Lower parts of the crust in the western Glennie Domain may be portions of the Sask craton that are significantly more complicated and comprise interleaved Archean and Paleoproterozoic rocks. The Sask craton includes rocks as old as 3. 10 Ga, but it is dominated by a ca. 2. 45 Ga magmatic event, and overprinted by metamorphism and deformation during the THO. The range in ages observed, together with Pb isotopic compositions, suggest that the Sask craton is not a fragment of the Superior or Hearne cratons. The Sask craton is associated with a crustal root that trends in a north-northeast direction of about 200 km. In addition, a lithosphere region may be spatially associated with the Sask craton lithosphere below the Fort à la Corne kimberlite. Kimberlite is a type of potassic Volcanic rock best known for sometimes containing Diamonds It is named after the town of Kimberley in South Africa However, the mantle lithosphere preserved below the Sask craton may have been replaced by Superior craton mantle lithosphere during orogenesis. ^[13]

Superior Boundary zone

The Superior Boundary zone is a narrow, southeastern, ensialic foreland zone bordering Superior craton, comprising the Thompson Belt, Split Lake Block, and Fox River Belt. Sial or SiAl is also the name for the upper layer of the Earth's crust, which is also known as the Continental crust because

Economic geology

The Reed Lake Belt is one of the largest Proterozoic volcanic-hosted massive sulfide (VMS) districts in the world, containing 27 Cu-Zn- (Au) deposits from which more than 183 million tonnes of ore have been mined. Volcanogenic massive sulfide ore deposits or VMS are a type of Metal Sulfide ore deposit, mainly Cu - Zn which are associated with and Most of mined VMS deposits in the Reed Lake belt are associated with juvenile arc volcanic rocks providing a powerful focus for future explorations. Gold mineralization has been less studied, but at Reed Lake has been shown to be associated with late brittle-ductile shear zones that follow peak tectonic and metamorphic activity within the Trans-Hudson Orogen. At Snow Lake, preliminary investigations suggest a long history of gold mineralization with at least some gold introduced prior to metamorphism. ^[12]

See also

• Canadian Shield
• North American craton
• Wyoming craton
• Superior craton
• Hearne craton
• Rae craton

References

• Trans-Hudsonian Suture--Collision of Superior with Hearne/Wyoming Province
• John B. Brady, et al, eds. (2004) Precambrian Geology of the Tobacco Root Mountains, Montana (Special Papers (Geological Society of America), 377. ) ISBN 0-8137-2377-9
• LITHOPROBE Seismic Processing Facility (LSPF). (1990). "Phase V Proposal - Executive Overview: Trans-Hudson Orogen Transect (THOT). [[1]]
• LITHOPROBE Seismic Processing Facility (LSPF). (1998). "Trans-Hudson Orogen Transect. " [[2]]