Journal articles: 'Microcontinental collision'

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Kusky, Timothy M., Xiaoyong Li, Zhensheng Wang, Jianmin Fu, Luo Ze, and Peimin Zhu. "Are Wilson Cycles preserved in Archean cratons? A comparison of the North China and Slave cratons." Canadian Journal of Earth Sciences 51, no. 3 (March 2014): 297–311. http://dx.doi.org/10.1139/cjes-2013-0163.

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A review and comparison of the tectonic history of the North China and Slave cratons reveal that the two cratons have many similarities and some significant differences. The similarities rest in the conclusion that both cratons have a history of a Wilson Cycle, having experienced rifting of an old continent in the late Archean, development of a rift to passive margin sequence, collision of this passive margin with arcs within 100–200 Ma of the formation of the passive margin, reversal of subduction polarity, then eventual climactic collision with another arc terrane, microcontinental fragment, or continent. This cycle demonstrates the operation of Paleozoic-style plate tectonics in the late Archean. The main differences lie in the later tectonic evolution. The Slave’s post-cratonization history is dominated by subduction dipping away from the interior of the craton, and later incorporation into the interior of a larger continent, whereas the North China Craton has had a long history of subduction beneath the craton, including presently being located above the flat-lying Pacific slab resting in the mantle transition zone, placing it in a broad back-arc setting, with multiple mantle hydration events and collisions along its borders. The hydration enhances melting in the overlying mantle, and leads to melts migrating upwards to thermochemically erode the lithospheric root. This major difference may explain why the relatively small Slave craton preserves its thick Archean lithospheric root, whereas the eastern North China Craton has lost it.

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Yumul, Graciano P., Carla B. Dimalanta, and Rodolfo A. Tamayo. "Indenter-tectonics in the Philippines: Example from the Palawan Microcontinental Block - Philippine Mobile Belt Collision." Resource Geology 55, no. 3 (September 2005): 189–98. http://dx.doi.org/10.1111/j.1751-3928.2005.tb00240.x.

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Sewell, Roderick J., Andrew Carter, and Martin Rittner. "Middle Jurassic collision of an exotic microcontinental fragment: Implications for magmatism across the Southeast China continental margin." Gondwana Research 38 (October 2016): 304–12. http://dx.doi.org/10.1016/j.gr.2016.01.005.

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Yumul, Graciano P., Carla B. Dimalanta, Edanjarlo J. Marquez, and Karlo L. Queaño. "Onland signatures of the Palawan microcontinental block and Philippine mobile belt collision and crustal growth process: A review." Journal of Asian Earth Sciences 34, no. 5 (May 2009): 610–23. http://dx.doi.org/10.1016/j.jseaes.2008.10.002.

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Zwanzig, Herman V. "Structure and stratigraphy of the south flank of the Kisseynew Domain in the Trans-Hudson Orogen, Manitoba: implications for 1.845-1.77 Ga collision tectonics." Canadian Journal of Earth Sciences 36, no. 11 (November 10, 1999): 1859–80. http://dx.doi.org/10.1139/e99-042.

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On the south flank of the Kisseynew Domain, orthogneisses derived from 1.92-1.85 Ga volcano-plutonic rocks are overlain by paragneisses (Burntwood and Missi groups) derived from 1.855-1.84 Ga marine turbidite and 1.845-1.83 Ga terrestrial clastic and volcanic rocks. The sediments in these groups are interpreted as having been shed into the Kisseynew paleobasin from an active margin bordering the Flin Flon Belt. The sedimentation apparently followed early microcontinental collision and accompanied the last arc magmatism in the Trans-Hudson Orogen. The sedimentary rocks and their basement were deformed into a complexly refolded stack of large recumbent folds. Premetamorphic F1 structures represent a fold and thrust system initiated during the sedimentation. These structures are interpreted as transported toward the Kisseynew Domain in the northeast and the hinterland in the southwest. F2 structures (~1.82 Ga) comprise westerly transported nappes. During 1.82-1.80 Ga high-grade metamorphism, the early structures were overturned, amplified, and refolded. Basement-cored culminations and sheet-like synforms of paragneiss were horizontally attenuated and transported south and southwest. North- and northeast-trending F4 folds and F5 faults formed after 1.79 Ga. The whole cycle of deformation is related to stages of continental collision between the internal (juvenile) zone of the Trans-Hudson Orogen and the three surrounding Archean cratons (Sask, Superior, and Hearne). The F4 upright folds and steep F5 faults are interpreted as the record of intracontinental transpression, strongly controlled by the Superior Craton boundary.

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Ross, Gerald M., and David W. Eaton. "Proterozoic tectonic accretion and growth of western Laurentia: results from Lithoprobe studies in northern Alberta." Canadian Journal of Earth Sciences 39, no. 3 (March 1, 2002): 313–29. http://dx.doi.org/10.1139/e01-081.

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The western Canadian Shield of northern Alberta is composed of a series of continental slivers that were accreted to the margin of the Archean Rae hinterland ca. 1.92.0 Ga., preserving a unique record of continental evolution for the interval 2.12.3 Ga. This part of Laurentia owes its preservation to the accretionary style of tectonic assembly south of the Great Slave Lake shear zone, which contrasts with indentationescape processes that dominate the Paleoproterozoic record farther north. The Buffalo Head and Chinchaga domains form the central core of this region, comprising a collage of ca. 23252045 Ma crustal elements formed on an Archean microcontinental edifice, and similar age crust is preserved as basement to the Taltson magmatic zone. The distribution of magmatic ages and inferred collision and subduction zone polarity are used to indicate closure of intervening oceanic basins that led to magmatism and emplacement of continental margin arc and collisional belts that formed from ca. 1998 to1900 Ma. Lithoprobe crustal seismic profiles complement the existing geochronologic and geologic databases for northern Alberta and elucidate the nature of late stages of the accretionary process. Crustal-scale imbrication occurred along shallow eastward-dipping shear zones, resulting in stacking of arc slivers that flanked the western Buffalo Head terrane. The seismic data suggest that strain is concentrated along the margins of these crustal slivers, with sparse evidence for internal penetrative deformation during assembly. Post-collisional mafic magmatism consisted of widespread intrusive sheets, spectacularly imaged as regionally continuous subhorizontal reflections, which are estimated to extend over a region of ca. 120 000 km2. The form of such mid-crustal magmatism, as subhorizontal sheets (versus vertical dykes), is interpreted to represent a style of magma emplacement within a confined block, for which a tectonic free face is unavailable.

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Neubauer, Franz, and Ana-Voica Bojar. "Origin of sediments during Cretaceous continent—continent collision in the Romanian Southern Carpathians: preliminary constraints from 40Ar/39Ar single-grain dating of detrital white mica." Geologica Carpathica 64, no. 5 (October 1, 2013): 375–82. http://dx.doi.org/10.2478/geoca-2013-0025.

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Abstract Single grains of detrital white mica from the lowermost Upper Cretaceous Sinaia Flysch have been dated using the 40Ar/39Ar technique. The Sinaia Flysch was deposited in a trench between the Danubian and Getic microcontinental pieces after the closure of the Severin oceanic tract. The Danubian basement is largely composed of a Panafrican/Cadomian basement in contrast to the Getic/Supragetic units with a Variscan-aged basement, allowing the distinction between these two blocks. Dating of detrital mica from the Sinaia Flysch resulted in predominantly Variscan ages (329 ± 3 and 288 ± 4 Ma), which prove the Getic/Supragetic source of the infill of the Sinaia Trench. Subordinate Late Permian (263 ± 8 and 255 ±10 Ma), Early Jurassic (185 ± 4 and 183 ± 3 Ma) and Late Jurassic/Early Cretaceous (149 ± 3 and 140 ± 3 Ma) ages as well as a single Cretaceous age (98 ± 4 Ma) are interpreted as representing the exposure of likely retrogressive low-grade metamorphic ductile shear zones of various ages. Ductile shear zones with similar 40Ar/39Ar white mica ages are known in the Getic/Supragetic units. The Cretaceous ages also show that Cretaceous metamorphic units were already subject to erosion during the deposition of the Sinaia Flysch.

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Sanborn-Barrie, M., and T. Skulski. "Sedimentary and structural evidence for 2.7 Ga continental arc–oceanic-arc collision in the Savant–Sturgeon greenstone belt, western Superior Province, Canada." Canadian Journal of Earth Sciences 43, no. 7 (July 1, 2006): 995–1030. http://dx.doi.org/10.1139/e06-060.

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The western Superior Province sustained rapid crustal growth in the interval 2.72–2.68 Ga through amalgamation of microcontinental crustal blocks and juvenile oceanic terranes. Recent field, isotopic, and geophysical surveys provide insight on the nature, timing, and scale of this accretionary growth. However, few places offer the rich tectono-stratigraphic and structural detail with which to establish accretion of oceanic and continental blocks as does the Savant–Sturgeon area. Here, 3.4–2.8 Ga continental crust of the Winnipeg River terrane is juxtaposed with 2.775–2.718 Ga juvenile oceanic rocks of the western Wabigoon terrane across a 2.85–2.75 Ga, southwest-facing, continental margin sequence. The continental margin was reactivated at ~2.715 Ga with the establishment of an arc, recorded by 2.715–2.70 Ga tonalite and associated intermediate volcanic rocks. This magmatic activity is interpreted to reflect north- and east-dipping subduction that led to consumption of a small tract of oceanic crust between the Winnipeg River and western Wabigoon terranes, ultimately leading to their amalgamation after 2.703 Ga. The telescoped fore arc also includes continental-derived turbiditic wacke, siltstone, and iron formation (Warclub assemblage) that are in tectonic contact with diverse oceanic rocks of the western Wabigoon terrane. Collision is bracketed between 2.703 Ga (the maximum age of marine fore arc deposits) and ~2.696 Ga (the minimum age of a late-tectonic pluton). Effects include thrust stacking and the development of shallow-plunging folds and bedding-parallel fabrics (D1), overprinted by steeply plunging inclined folds, steep foliations, and shear zones (D2). Collectively, these structures have penetratively reworked the suture between the ancient fore-arc and oceanic rocks in the Savant–Sturgeon area.

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Sun, Min, Kurt Kyser, Mel Stauffer, Rob Kerrich, and John Lewry. "Constraints on the timing of crustal imbrication in the central Trans-Hudson Orogen from single zircon 207Pb/206Pb ages of granitoid rocks from the Pelican thrust zone, Saskatchewan." Canadian Journal of Earth Sciences 33, no. 12 (December 1, 1996): 1638–47. http://dx.doi.org/10.1139/e96-124.

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The Pelican thrust is a major ductile high-strain zone in the Reindeer Zone, Trans-Hudson Orogen, northern Saskatchewan. It is interpreted as the main sole thrust separating stacked juvenile Paleoproterozoic allochthons and underlying Archean microcontinental crust in this central part of the orogen. Exposed nonmylonitic rocks in the footwall of the thrust consist of the Sahli monzocharnockite and the smaller, more highly retrograded MacMillan Point granite. Protomylonitic to ultramylonitic gneisses in the thrust zone derive from a variety of prethrust protoliths. A footwall "internal suite" mainly comprises quartzofeldspathic orthogneisses ("Q" gneisses) and high-grade migmatitic paragneisses. Hanging-wall "external suite" mylonitic gneisses include feldspar-porphyroclastic hornblendic grey gneisses probably derived from arc plutons, and laminated amphibolites derived from volcanic rocks. The overlying allochthon mainly comprises protoliths equivalent to those of the porphyroclastic orthogneisses and laminated amphibolites, together with interfolded and overlying Paleoproterozoic paragneisses of the Kisseynew domain. The Sahli monzoeharnockite yields 207Pb/206Pb zircon and whole-rock Rb–Sr ages of ca. 2500 Ma, and the "Q" gneisses give 207Pb/206Pb zircon ages of up to ca 2900 Ma, implying that most of the internal suite (footwall) mylonite protoliths are Archean. In contrast, external suite (hanging wall) porphyroclastic orthogneisses yield ca. 1880–1840 Ma 207Pb/206Pb zircon ages. Main, peak-metamorphic displacement on the Pelican thrust is interpreted to have occurred mainly between 1840 and 1820 Ma, as indicated by 207Pb/206Pb zircon ages from small, highly deformed synthrusting granite–pegmatite neosomal bodies in the thrust zone. Undeformed postcollisional granites and pegmatites were emplaced~1789 Ma. Total duration from arc development to completion of arc–continent collision was ~100 Ma. The Pelican thrust zone may be similar in significance and style to younger, major, ocean closure related thrusts such as the Frontal Pennine thrust of the western Alps and the Main Mantle, Main Boundary, and Main Central thrusts of the Himalayas. As for the Pelican thrust, these displace oceanic rocks over older basement.

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Soper, N. J., and N. H. Woodcock. "Silurian collision and sediment dispersal patterns in southern Britain." Geological Magazine 127, no. 6 (November 1990): 527–42. http://dx.doi.org/10.1017/s0016756800015430.

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AbstractThe evidence is reviewed for the timing of collision between the microcontinent of Eastern Avalonia (southern Britain and adjacent areas) and the Laurentian continent. Recent palaeomagnetic results placing Eastern Avalonia in a high (50°) southern latitude in mid Ordovician time are now consistent with faunal evidence for the first time. The resulting apparent polar wander path is evaluated and suggests that Eastern Avalonia detached itself from a southern peri-Gondwanan latitude in the early Ordovician, moved northwards, and approached Laurentia by the late Ordovician. Its western corner probably impinged on Laurentia in the early Silurian and it docked against the Laurentian margin during Silurian and early Devonian time with a component of anticlockwise rotation.This kinematic history is supported by a compilation of sediment dispersal patterns on Eastern Avalonia. A low-volume Ordovician and earliest Silurian supply from within the microcontinent was overwhelmed in late Llandovery time by a large volume of southwest-derived turbidites, probably from the uplifting impact zone to the west. This source was later augmented by a high-volume clastic supply to the north margin of the microcontinent. Eastward migration of this source through Wenlock and Ludlow time reflects the progressive anticlockwise docking of Eastern Avalonia against the Laurentian margin. The earliest sign of a large-volume supply from Baltica is in the late Wenlock, arguing against any earlier hard collision.

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Vernikovsky, Valery A., Antonina Vernikovskaya, Vasilij Proskurnin, Nikolay Matushkin, Maria Proskurnina, Pavel Kadilnikov, Alexander Larionov, and Alexey Travin. "Late Paleozoic–Early Mesozoic Granite Magmatism on the Arctic Margin of the Siberian Craton during the Kara-Siberia Oblique Collision and Plume Events." Minerals 10, no. 6 (June 25, 2020): 571. http://dx.doi.org/10.3390/min10060571.

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We present new structural, petrographic, geochemical and geochronological data for the late Paleozoic–early Mesozoic granites and associated igneous rocks of the Taimyr Peninsula. It is demonstrated that large volumes of granites were formed due to the oblique collision of the Kara microcontinent and the Siberian paleocontinent. Based on U-Th-Pb isotope data for zircons, we identify syncollisional (315–282 Ma) and postcollisional (264–248 Ma) varieties, which differ not only in age but also in petrochemical and geochemical features. It is also shown that as the postcollisional magmatism was coming to an end, Siberian plume magmatism manifested in the Kara orogen and was represented by basalts and dolerites of the trap formation (251–249 Ma), but also by differentiated and individual intrusions of monzonites, quartz monzonites and syenites (Early–Middle Triassic) with a mixed crustal-mantle source. We present a geodynamic model for the formation of the Kara orogen and discuss the relationship between collisional and trap magmatism.

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Suliantara, Suliantara, and Tri Muji Susantoro. "HYDROCARBON POTENTIAL OF TOLO BAY MOROWALI REGENCY: QUALITATIVE ANALYSIS." Scientific Contributions Oil and Gas 38, no. 1 (May 1, 2015): 13–24. http://dx.doi.org/10.29017/scog.38.1.536.

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Tolo Bay is located between East Arm and Southeast Arm Sulawesi, reaching a water depth of up to 3500 meters below sea level. Regionally, this block is situated within Banggai Basin where some gas and oil fi elds are already in production. The closest fi eld is Tiaka Oil Field located about 125 kilometers northwest of the study area. A geo-science review has been conducted to clarify the potential existence of hydrocarbon in this block. Based on previous reports, papers, and subsurface data from the Directorate General of Oil and Gas, the study area is located within the collision area between Banggai-Sula Microcontinent and Sulawesi. This collision occurred during Late Creataceous and Middle Miocene periods. During drifting phase a sedimentation process occurred at the front of the Banggai-Sula Microcontinent. This sediment is potentially source rock and reservoir rock. Meanwhile, during the drifting phase the study area is interpreted as located at the southern part of Banggai-Sula Microcontinent. This different tectonic setting will impact on the type of sedimentary rock, hence source rock and reservoir rock occurrence in the study area is still unclear. As source rock and reservoir rock within the study area are unclear, hydrocarbon explorations will be very risky. In order to reduce exploration risk, it is proposed to conduct geological and geophysical studies using the latest seismic data that was surveyed by PT. TGS – NOPEC and PT. ECI – PGS.

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Burtman, V. S., A. V. Dvorova, and S. G. Samygin. "Latitudes of the Eastern Ural microcontinent and Magnitogorsk island arc in the Paleozoic Ural Ocean." LITHOSPHERE (Russia) 20, no. 6 (December 29, 2020): 842–50. http://dx.doi.org/10.24930/1681-9004-2020-20-6-842-850.

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Research subject. Rocks of the Paleozoic Eastern Ural microcontinent and Magnitogorsk island arc occupy a significant part of the Southern Urals and some part of the Middle Urals. The Western Urals are composed of rocks of the ancient Baltic continent and overthrust oceanic rocks. In the Eastern Urals and Trans-Urals rocks of the accretion complexes, oceanic crust, island arcs, the Eastern Ural microcontinent and the Kazakhstan Paleozoic continent are widespread. Rocks are exposed in the Denisov tectonic zone. The Magnitogorsk simatic Island Arc originated in the Ural Ocean, near the Baltic continent, in the early Devonian, developing from the Emsian to the Famennian. A collision between the Magnitogorsk arc and the Baltic continent occurred in the Famennian century. In the pre-Carboniferous age, the Eastern Ural microcontinent was located in the Ural Ocean. In the Tournaisian period, the Eastern Ural microcontinent accreted with the Baltic continent. The Kazakhstan continental massif was located on the other side of the Ural Ocean. The volcanic belt above the subduction zone was active on the edge of the Kazakhstan continent in the Early–Middle Devonian and in the Early Carboniferous. A subduction under the Baltic and Kazakhstan continents consumed most of the crust of the Ural Ocean by the middle of the Bashkir century. As a result, the Baltic continent (together with the Eastern Ural microcontinent) came into contact with the Kazakhstan continent. The formation of folded orogen began in the Moscow century following the collision of sialic terrains.Materials and methods. The research was based on the relevant data obtained by several researchers in 2000–2018 on rock paleomagnetism. Results. The paleolatitudinal positions of the Eastern Ural microcontinent were determined, comprising 5.3 ± 7.4°) in the Middle Ordovician and 8.2 ± 7.2° in the Early–Middle Silurian. The respective paleolatitudinal positions for the Early–Middle Devonian comprised: the Ural margin of the Baltic paleocontinent (7.7 ± 3.7°), the Magnitogorsk island arc (3.2 ± 3.1°) and the Ural margin of the Kazakhstan paleocontinent (20.6 ± 3.8°).Conclusion. According to the analysed paleomagnetic data, in the Early–Middle Devonian, the distance between the latitudes of the margins of the Baltic and Kazakhstan continents was not less than 600 km provided they were in the same hemisphere, and more than 2,300 km provided they were in different hemispheres. The convergence of the terrains was associated with the subduction of the Ural Ocean crust before its closure, which occurred in the Tournaisian century.

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Searle, Michael P. "Tectonic evolution of the Caledonian orogeny in Scotland: a review based on the timing of magmatism, metamorphism and deformation." Geological Magazine 159, no. 1 (October 15, 2021): 124–52. http://dx.doi.org/10.1017/s0016756821000947.

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AbstractClassic tectonic models for the Caledonian orogeny in Scotland involve Ordovician collision of Laurentia–Midland Valley arc (Grampian orogeny), followed by middle Silurian collision of Laurentia–Baltica (Scandian orogeny) and 500–700 km of sinistral displacement along the Great Glen fault separating the Northern Highlands (Moine Supergroup) from the Grampian Highlands (Dalradian Supergroup). A review of the timing of magmatic and metamorphic rocks across Scotland allows a simpler explanation that fits with a classic Himalayan-style continent–island arc–continent collision. Late Cambrian – Early Ordovician NW-directed ophiolite obduction (Highland Border complex) coincided with the ending of stable continental shelf sedimentation along the eastern margin of Laurentia. Following collision between Laurentia and the Midland Valley arc–microcontinent in Early Ordovician time, crustal thickening and shortening led to almost continuous regional metamorphism from c. 470 to 420 Ma, rather than two discrete ‘orogenies’ (Grampian, Scandian). U–Pb monazite and garnet growth ages indicating prograde metamorphism, and S-type granites related to melting of crustal protoliths are coeval in the Grampian and Northern Highlands terranes. There is no evidence that the Great Glen fault was a terrane boundary, and strike-slip shearing post-dated emplacement of Silurian – Early Devonian granites. Late orogenic alkaline granites (c. 430–405 Ma) in both Moine and Dalradian terranes are not associated with subduction. They are instead closely related to regional alkaline appinite–lamprophyric magmatism resulting from simultaneous melting of lower crust and enriched lithospheric mantle. Caledonian deformation and metamorphism in northern Scotland, with continuous SE-directed subduction, show geometry and time scales that are comparable to the Cenozoic India–Kohistan arc–Asia collisional Himalayan orogeny.

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Montenat, Christian. "The Mesozoic of Afghanistan." GeoArabia 14, no. 1 (January 1, 2009): 147–210. http://dx.doi.org/10.2113/geoarabia1401147.

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ABSTRACT This paper is a review of the geology of the widely distributed Mesozoic rocks of Afghanistan. The country is a mosaic of structural blocks in a variety of geodynamic settings that were juxtaposed during the evolution of the Tethyan Ocean; the Mesozoic sedimentary, volcanic, and plutonic rocks therefore differ greatly from one block to another. Because of the adverse security situation, fieldwork has not been possible since the late 1970s and the data used in this review are therefore relatively old but are the best available. Interest in the geology of Afghanistan remains strong due to its position between the mountain chains of the Middle East and the collisional ranges of the Pamirs and Himalayas. A special feature of Tethyan geodynamics is the presence of Cimmerian (latest Triassic to earliest Cretaceous) continental blocks, microcontinents, or terranes located between the Eurasian and Indian landmasses. They are fragments of Gondwana inserted between the Paleo- and Neo-Tethys during the Mesozoic. This complex part of the Tethyan realm is well exposed in Afghanistan where the effects of the Indo-Eurasian collision were less intense than in regions of frontal collision, such as the Pamir and Himalayan ranges. It is for this reason that Afghanistan is of particular geodynamic interest and a key region in the understanding of the genesis and evolution of the Tethyan system during the Mesozoic.

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Gün, Erkan, Russell N. Pysklywec, Oğuz H. Göğüş, and Gültekin Topuz. "Pre-collisional extension of microcontinental terranes by a subduction pulley." Nature Geoscience 14, no. 6 (May 10, 2021): 443–50. http://dx.doi.org/10.1038/s41561-021-00746-9.

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Prokopiev, A. V., and V. S. Oxman. "Multi-phase tectonic structures in the collision zone of the Kolyma-Omolon microcontinent and the eastern margin of the North Asian craton, Northeastern Russia." Stephan Mueller Special Publication Series 4 (September 17, 2009): 65–70. http://dx.doi.org/10.5194/smsps-4-65-2009.

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Abstract. The sequence of formation of structures is established in the zone of junction of the eastern margin of the North Asian craton and the northeastern flank of the Kolyma-Omolon microcontinent, in the area of bend of the Kolyma structural loop. Detailed structural studies revealed two phases in the formation of Mesozoic structures – an early thrust phase and a late strike-slip phase. Structures formed during each of the phases are described. Thrust structures are represented by the Setakchan nappe on which the minimum amount of horizontal displacement is estimated at 13–15 km. Later superposed left-lateral strike-slip faults have a north strike. Formation of these latter structures occurred during the second phase of collision between the Kolyma-Omolon microcontinent and the eastern margin of the North Asian craton.

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Keppie, J. Duncan, and D. Fraser Keppie. "Ediacaran–Middle Paleozoic Oceanic Voyage of Avalonia from Baltica via Gondwana to Laurentia: Paleomagnetic, Faunal and Geological Constraints." Geoscience Canada 41, no. 1 (March 4, 2014): 5. http://dx.doi.org/10.12789/geocanj.2014.41.039.

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Current Ediacaran–Cambrian, paleogeographic reconstructions place Avalonia, Carolinia and Ganderia (Greater Avalonia) at high paleolatitudes off northwestern Gondwana (NW Africa and/or Amazonia), and locate NW Gondwana at either high or low paleolatitudes. All of these reconstructions are incompatible with 550 Ma Avalonian paleomagnetic data, which indicate a paleolatitude of 20–30ºS for Greater Avalonia and oriented with the present-day southeast margin on the northwest side. Ediacaran, Cambrian and Early Ordovician fauna in Avalonia are mainly endemic, which suggests that Greater Avalonia was an island microcontinent. Except for the degree of Ediacaran deformation, the Neoproterozoic geological records of mildly deformed Greater Avalonia and the intensely deformed Bolshezemel block in the Timanian orogen into eastern Baltica raise the possibility that they were originally along strike from one another, passing from an island microcontinent to an arc-continent collisional zone, respectively. Such a location and orientation is consistent with: (i) Ediacaran (580–550 Ma) ridge-trench collision leading to transform motion along the backarc basin; (ii) the reversed, ocean-to-continent polarity of the Ediacaran cratonic island arc recorded in Greater Avalonia; (iii) derivation of 1–2 Ga and 760–590 Ma detrital zircon grains in Greater Avalonia from Baltica and the Bolshezemel block (NE Timanides); and (iv) the similarity of 840–1760 Ma TDM model ages from detrital zircon in pre-Uralian–Timanian and Nd model ages from Greater Avalonia. During the Cambrian, Greater Avalonia rotated 150º counterclockwise ending up off northwestern Gondwana by the beginning of the Ordovician, after which it migrated orthogonally across Iapetus to amalgamate with eastern Laurentia by the Late Ordovician–Early Silurian. SOMMAIRELes reconstitutions paléogéographiques courantes de l’Édiacarien-Cambrien placent l’Avalonie ,la Carolinia et la Ganderia (Grande Avalonie) à de hautes paléolatitudes au nord-ouest du Gondwana (N-O de l'Afrique et/ou de l'Amazonie), et placent le N-O du Gondwana à de hautes ou de basses paléolatitudes. Toutes ces reconstitutions sont incompatibles avec des données avaloniennes de 550 Ma, lesquelles indiquent une paléolatitude de 20-30º S pour la Grande Avalonie et orientée à la marge sud-est d’aujourd'hui sur le côté nord-ouest. Les faunes édicacariennes, cambriennes et de l'Ordovicien précoce dans l’Avalonie sont principalement endémiques, ce qui permet de penser que la Grande Avalonie était une île de microcontinent. Sauf pour le degré de déformation édiacarienne, les registres géologiques néoprotérozoïques d’une Grande Avalonie légèrement déformée et ceux du bloc intensément déformé de Bolshezemel dans l'orogène Timanian dans l’est de la Baltica soulèvent la possibilité qu'ils aient été à l'origine de même direction, passant d'une île de microcontinent à une zone de collision d’arc continental, respectivement. Un tel emplacement et une telle orientation sont compatibles avec: (i) un contexte de collision crête-fosse à l’Édiacarien (580-550 Ma) se changeant en un mouvement de transformation le long du bassin d’arrière-arc; (ii) l’inversion de polarité de marine à continentale, de l’arc insulaire cratonique édicarien observé dans la Grande Avalonie; (iii) la présence de grains de zircons détritiques de 1 à 2 Ga et 760-590 Ma de la Grande Avalonie issus de la Baltica et du bloc Bolshezemel (N-E des Timanides); et (iv) la similarité des âges modèles de 840-1760 Ma TDM de zircons détritiques pré-ourallien-timanien, et des âges modèles Nd de la Grande Avalonie. Durant le Cambrien, la Grande Avalonie a pivoté de 150° dans le sens antihoraire pour se retrouver au nord-ouest du Gondwana au début de l'Ordovicien, après quoi elle a migré orthogonalement à travers l’océan Iapetus pour s’amalgamer à la bordure est de la Laurentie à la fin de l’Ordovicien-début du Silurien.

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Buslov, M. M. "Stress-strain state of the earth’s crust of the Central Asian mountain belt: distant effect of the tectonic impact of the Indo-Eurasian collision." IOP Conference Series: Earth and Environmental Science 929, no. 1 (November 1, 2021): 012003. http://dx.doi.org/10.1088/1755-1315/929/1/012003.

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Abstract In recent decades, extensive geological, geophysical and geochronological data have been obtained that characterize in detail the results of the distant tectonic impact of the Indo-Eurasian collision on the lithosphere of Central Asia, which led to the formation of the mountain systems of the Pamirs, Tien Shan, Altai-Sayan region and Transbaikalia from the Late Paleogene (about 25 million years ago). It has been established that the formation of the structure of Central Asia occurred as a result of the transmission of deformations from the Indo-Eurasian collision over long distances according to the “domino principle” through the rigid structures of Precambrian microcontinents located among the Paleozoic-Mesozoic folded belts. The study of peneplain surfaces deformed into simple folds on high-mountain plateaus surrounded by rugged mountain ranges made it possible to reveal the parameters of the deformations of the earth’s crust, the interrelationship of the formation of relief and sedimentary basins. Apatite track dating data, structural and stratigraphic analyses of Late Cenozoic sediments in the basins prove a period of intense tectonic activation the entire lithosphere of Central Asia from the Indian continent to the Siberian platform starting from the Pliocene (about 3.5 million years). As a result of reactivation of the heterogeneous basement of Central Asia, high seismicity was manifested, which is concentrated mainly along the border of the microcontinents (Central Tianshan, Junggar and Tuva-Mongolian) and the Siberian craton, as well as in the zones of articulation of regional faults.

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MAZUR, STANISŁAW, ALFRED KRÖNER, JACEK SZCZEPAŃSKI, KRZYSZTOF TURNIAK, PAVEL HANŽL, ROSTISTLAV MELICHAR, NICKOLAY V. RODIONOV, ILYA PADERIN, and SERGEY A. SERGEEV. "Single zircon U–Pb ages and geochemistry of granitoid gneisses from SW Poland: evidence for an Avalonian affinity of the Brunian microcontinent." Geological Magazine 147, no. 4 (January 15, 2010): 508–26. http://dx.doi.org/10.1017/s001675680999080x.

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AbstractSeven granitoid gneisses from the contact zone between the eastern margin of the Variscan belt and the Brunian microcontinent in SW Poland have been dated by ion-microprobe and207Pb/206Pb single zircon evaporation methods. The zircons define two age groups for the gneiss protoliths: (1) late Neoproterozoicc.576–560 Ma and (2) early Palaeozoicc.488–503 Ma granites. The granitoid gneisses belonging to the basement of the Brunian microcontinent contain abundant Mesoproterozoic to latest Palaeoproterozoic inherited material in the range of 1200–1750 Ma. The gneisses of the Variscan crustal domain lack Mesoproterozoic inherited zircon cores. Trace element geochemistry of Proterozoic gneisses reveals features resembling either volcanic arc or post-collisional granites. The studied rocks are geochemically similar to other Proterozoic orthogneisses derived from the basement of the Brunian microcontinent. Gneisses with early Palaeozoic protolith ages are geochemically comparable to granitoid gneisses widespread in the adjacent Sudetic part of the Bohemian Massif and are considered characteristic of peri-Gondwanan crust. Our data prove the dissimilarity between the Brunia plate and the westerly terranes of the Variscan belt. The occurrence of granitic gneisses with late Neoproterozoic protolith ages and widespread Mesoproterozoic inheritance in our dated samples support an East Avalonian affinity for the Brunian microcontinent. In contrast, the abundance of gneisses derived from an early Palaeozoic granitic protolith and devoid of Mesoproterozoic zircon cores supports the Armorican affinity of the Variscan domain bordering on the Brunia plate from the west. Structural evidence shows that the eastern segment of the Variscan belt is juxtaposed against the Brunian microcontinent along a N–S-trending tectonic contact, possibly equivalent to the Rheic suture.

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Jolivet, Laurent, Jean Paul Cadet, and Frédéric Lalevée. "Mesozoic evolution of Northeast Asia and the collision of the okhotsk microcontinent." Tectonophysics 149, no. 1-2 (June 1988): 89–109. http://dx.doi.org/10.1016/0040-1951(88)90120-5.

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22

Ring, U., K. Gessner, S. Thomson, and V. Markwitz. "Along-strike variations in the Hellenide Anatolide orogen: A tale of different lithospheres and consequences." Bulletin of the Geological Society of Greece 47, no. 2 (January 24, 2017): 625. http://dx.doi.org/10.12681/bgsg.11096.

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Structure and exhumation history of the Hellenide-Anatolide Orogen in the Aegean Sea region and the adjacent Anatolian peninsula is controlled by along-strike variations of pre-Alpine palaeogeography. In the Hellenides, Mesozoic extension created ribbon-like continental fragments of thinned and dense lithosphere that pinch out eastwards. In the east, the relatively large Anatolide microcontinent mostly escaped Mesozoic extension and lithospheric thinning, presumably because it had a distinctly different, thicker and more depleted lithosphere. In the Aegean transect these alongstrike differences in lithosphere structure ultimately resulted in sustained highpressure metamorphism followed by progressive slab retreat since about 60 Ma. Further east, collision of the Anatolide microcontinent at about 42 Ma formed a south verging greenschist-facies thrust-and-fold belt. Pronounced slab retreat in the Aegean forced differential extension resulting in a broad sinistral wrench corridor that started to from at 24-23 Ma. Since then, extension in both regions mainly controlled denudation. This review highlights how differences in pre-orogenic architecture control lithospheric thickening and the subsequent exhumation of high-pressure rocks, and how large-scale continental extension evolves

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Ghanbarian, Mohammad Ali, Ali Yassaghi, and Reza Derakhshani. "Detecting a Sinistral Transpressional Deformation Belt in the Zagros." Geosciences 11, no. 6 (May 24, 2021): 226. http://dx.doi.org/10.3390/geosciences11060226.

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The oblique collision between the northeastern margin of the Arabian platform and the Iranian microcontinent has led to transpressional deformation in the Zagros orogenic belt in the central part of the Alpine–Himalayan orogenic belt. Although previous articles have emphasized the dextral sense of shear in the Zagros orogenic belt, in this paper, using several indicators of kinematic shear sense upon field checking and microscopic thin-section studies, evidence of the development of a sinistral top-to-the NW deformation belt is presented. The mean attitudes of the foliations and lineations in this belt are 318°/55°NE and 19°/113°, respectively.

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Michard, André, Ahmed Chalouan, Hugues Feinberg, Bruno Goffé, and Raymond Montigny. "How does the Alpine belt end between Spain and Morocco ?" Bulletin de la Société Géologique de France 173, no. 1 (January 1, 2002): 3–15. http://dx.doi.org/10.2113/173.1.3.

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Abstract The Betic-Rif arcuate mountain belt (southern Spain, northern Morocco) has been interpreted as a symmetrical collisional orogen, partly collapsed through convective removal of its lithospheric mantle root, or else as resulting of the African plate subduction beneath Iberia, with further extension due either to slab break-off or to slab retreat. In both cases, the Betic-Rif orogen would show little continuity with the western Alps. However, it can be recognized in this belt a composite orocline which includes a deformed, exotic terrane, i.e. the Alboran Terrane, thrust through oceanic/transitional crust-floored units onto two distinct plates, i.e. the Iberian and African plates. During the Jurassic-Early Cretaceous, the yet undeformed Alboran Terrane was part of a larger, Alkapeca microcontinent bounded by two arms of the Tethyan-African oceanic domain, alike the Sesia-Margna Austroalpine block further to the northeast. Blueschist- and eclogite-facies metamorphism affected the Alkapeka northern margin and adjacent oceanic crust during the Late Cretaceous-Eocene interval. This testifies the occurrence of a SE-dipping subduction zone which is regarded as the SW projection of the western Alps subduction zone. During the late Eocene-Oligocene, the Alkapeca-Iberia collision triggered back-thrust tectonics, then NW-dipping subduction of the African margin beneath the Alboran Terrane. This Maghrebian-Apenninic subduction resulted in the Mediterranean basin opening, and drifting of the deformed Alkapeca fragments through slab roll back process and back-arc extension, as reported in several publications. In the Gibraltar area, the western tip of the Apenninic-Maghrebian subduction merges with that of the Alpine-Betic subduction zone, and their Neogene roll back resulted in the Alboran Terrane collage astride the Azores-Gibraltar transpressive plate boundary. Therefore, the Betic-Rif belt appears as an asymmetrical, subduction/collision orogen formed through a protracted evolution straightfully related to the Alpine-Apenninic mountain building.

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Bhandari, Saunak, Wenjiao Xiao, Songjian Ao, Brian F. Windley, Rixiang Zhu, Rui Li, Hao Y. C. Wang, and Rasoul Esmaeili. "Rifting of the northern margin of the Indian craton in the Early Cretaceous: Insight from the Aulis Trachyte of the Lesser Himalaya (Nepal)." Lithosphere 11, no. 5 (July 12, 2019): 643–51. http://dx.doi.org/10.1130/l1058.1.

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Abstract To reconstruct the early tectonic history of the Himalayan orogen before final India-Asia collision, we carried out geochemical and geochronological studies on the Early Cretaceous Aulis Trachyte of the Lesser Himalaya. The trace-element geochemistry of the trachytic lava flows suggests formation in a rift setting, and zircon U-Pb ages indicate that volcanism occurred in Early Cretaceous time. The felsic volcanics show enrichment of more incompatible elements and rare earth elements, a pattern that is identical to the trachyte from the East African Rift (Kenya rift), with conspicuous negative anomalies of Nb, P, and Ti. Although much of the zircon age data are discordant, they strongly suggest an Early Cretaceous eruption age, which is in agreement with the fossil age of intravolcanic siltstones. The Aulis Trachyte provides the first corroboration of Cretaceous rifting in the Lesser Himalaya as suggested by paleomagnetic data associated with the concept that the northern margin of India separated as a microcontinent and drifted north in the Neo-Tethys before terminal collision of India with Asia.

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Andersen, Torgeir B., Johannes Jakob, Hans Jørgen Kjøll, and Christian Tegner. "Vestiges of the Pre-Caledonian Passive Margin of Baltica in the Scandinavian Caledonides: Overview, Revisions and Control on the Structure of the Mountain Belt." Geosciences 12, no. 2 (January 25, 2022): 57. http://dx.doi.org/10.3390/geosciences12020057.

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The Pre-Caledonian margin of Baltica has been outlined as a tapering wedge with increasing magmatism towards the ocean–continent transition. It is, however, well known that margins are complex, with different and diachronous evolution along and across strike. Baltica’s vestiges in the Scandes have complexities akin to modern margins. It included a microcontinent and magma-poor hyperextended and magma-rich segments. It was probably up to 1500 km wide before distal parts were affected by plate convergence. Characteristic features are exhumed mantle peridotites and their detrital equivalents, some exposed to the seafloor by the pre-orogenic hyperextension. A major change in the architecture of the mountain belt occurred across the NW–SE trending Sveconorwegian front in the Baltican basement. This coincided with the NE termination of the Jotun-Lindås-Dalsfjord basement nappes, the remains of the Jotun Microcontinent (JMC) formed by hyperextension prior to the orogeny. Mantle with ophicalcite breccias exhumed by hyperextension are covered by deep-marine sediments and local conglomerates. Baltican basement slivers are common in the transitional crust basins. Outboard the JMC, the margin was magma-rich. The main break-up magmatism at 605 ± 10 Ma was part of the vast Central Iapetus Magmatic Province. The along-strike heterogeneity of the margin controlled diachronous and contrasting tectonic evolution during the later Caledonian plate convergence and collision.

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Saktura, Wanchese M., Solomon Buckman, Allen P. Nutman, and Renjie Zhou. "Jurassic–Cretaceous arc magmatism along the Shyok–Bangong Suture of NW Himalaya: formation of the peri-Gondwana basement to the Ladakh Arc." Journal of the Geological Society 179, no. 2 (September 29, 2021): jgs2021–035. http://dx.doi.org/10.1144/jgs2021-035.

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The Jurassic–Cretaceous Tsoltak Formation of the eastern borderlands of Ladakh Himalaya consists of conglomerates, sandstones and shales, and is intruded by norite sills. It is the oldest sequence of continent-derived sedimentary rocks within the Shyok Suture. It also represents a rare outcrop of the basement rocks to the voluminous Late Cretaceous–Eocene Ladakh Batholith. The Shyok Formation is a younger sequence of volcaniclastic rocks that overlie the Tsoltak Formation and record the Late Cretaceous closure of the Mesotethys Ocean. The petrogenesis of these formations, ophiolite-related harzburgites and norite sill is investigated through petrography, whole-rock geochemistry and U–Pb zircon geochronology. The youngest detrital zircon grains from the Tsoltak Formation indicate an Early Cretaceous maximum depositional age and a distinctly Gondwanan, Lhasa microcontinent-related provenance with no Eurasian input. The Shyok Formation has a Late Cretaceous maximum depositional age and displays a distinct change in provenance to igneous detritus characteristic of the Jurassic–Cretaceous magmatic arc along the southern margin of Eurasia. This is interpreted as a sign of collision of the Lhasa microcontinent and the Shyok ophiolite with Eurasia along the once continuous Shyok–Bangong Suture. The accreted terranes became the new southernmost margin of Eurasia and the basement to the Trans-Himalayan Batholith associated with the India–Eurasia convergence.Supplementary material: Supplementary figures and Tables S1–S3 are available at https://doi.org/10.6084/m9.figshare.c.5633162

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von Raumer, Jürgen F., Gérard M. Stampfli, and François Bussy. "Gondwana-derived microcontinents — the constituents of the Variscan and Alpine collisional orogens." Tectonophysics 365, no. 1-4 (April 2003): 7–22. http://dx.doi.org/10.1016/s0040-1951(03)00015-5.

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29

Vernikovsky, V. A., O. P. Polyansky, A. B. Babichev, A. E. Vernikovskaya, V. F. Proskurnin, and N. Yu Matushkin. "Tectonothermal Model for the Late Paleozoic Syncollisional Formation Stage of the Kara Orogen (Northern Taimyr, Central Arctic)." Russian Geology and Geophysics 63, no. 4 (April 1, 2022): 368–82. http://dx.doi.org/10.2113/rgg20214426.

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Abstract We present a tectonothermal model for the late Paleozoic syncollisional formation stage of the Kara orogen in northern Taimyr in the Central Arctic. The model is based on new and published structural, petrological, geochemical, and geochronological data, as well as thermophysical properties obtained for the Kara orogen. The latter hosts a significant volume of granites formed as a result of the collision between the Kara microcontinent and the Siberian craton. Based on geological, geochemical, and U–Th–Pb isotope data, the granites were differentiated into syncollisional and postcollisional intrusions that were emplaced in the intervals 315–282 and 264–248 Ma, respectively. The presented tectonothermal model covers only the syncollisional formation stage of the Kara orogen, during which anatectic granites formed. The 2D models help to reconstruct the main tectonothermal processes of the syncollisional stage of formation of this structure, taking into account the local peculiarities of the thermal state of the Earth’s crust in the region. The model shows the mechanisms of increase in the lower crust temperature necessary for the formation of syncollisional anatectic granites. The estimates obtained from the model constrain the time interval between collision/tectonic stacking and the granite formation. The modeling also showed the general regularities typical for orogens on syncollisional stages.

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Bird, P. R., N. A. Quinton, M. N. Beeson, and C. Bristow. "Mindoro: a rifted microcontinent in collision with the Philippines volcanic arc; basin evolution and hydrocarbon potential." Journal of Southeast Asian Earth Sciences 8, no. 1-4 (January 1993): 449–68. http://dx.doi.org/10.1016/0743-9547(93)90045-q.

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31

Mohammadi, Nadia, Les Fyffe, Christopher R. M. McFarlane, Kay G. Thorne, David R. Lentz, Brittany Charnley, Laurin Branscombe, and Sheena Butler. "Geological relationships and laser ablation ICP-MS U-Pb geochronology of the Saint George Batholith, southwestern New Brunswick, Canada: implications for its tectonomagmatic evolution." Atlantic Geology 53 (May 6, 2017): 207–40. http://dx.doi.org/10.4138/atlgeol.2017.008.

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The Late Silurian to Late Devonian Saint George Batholith in southwestern New Brunswick is a large composite intrusion (2000 km2) emplaced into the continental margin of the peri-Gondwanan microcontinent of Ganderia. The batholith includes: (1) Bocabec Gabbro; (2) equigranular Utopia and Wellington Lake biotite granites; (3) Welsford, Jake Lee Mountain, and Parks Brook peralkaline granites; (4) two-mica John Lee Brook Granite; (6) Jimmy Hill and Magaguadavic megacrystic granites; and (6) rapakivi Mount Douglas Granite. New LA ICP-MS in situ analyses of six samples from the Saint George Batholith are as follows: (1) U-Pb monazite crystallization age of 425.5 ± 2.1 Ma for the Utopia Granite in the western part of the batholith (2) U-Pb zircon crystallization ages of 420.4 ± 2.4 Ma and 420.0 ± 3.5 Ma for two samples of the Utopia Granite from the central part of the batholith; (3) U-Pb zircon crystallization age of 418.0 ± 2.3 Ma for the Jake Lee Mountain Granite; (4) U-Pb zircon crystallization age of 415.5 ± 2.1 Ma for the Wellington Lake Granite; and (5) U-Pb monazite crystallization age of 413.3 ± 2.1 Ma for the John Lee Brook Granite. The new geochronological together with new and existing geochemical data suggest that the protracted magmatic evolution of the Late Silurian to Early Devonian plutonic rocks is related to the transition of the Silurian Kingston arc-Mascarene backarc system from an extensional to compressional tectonic environment during collision of the Avalonian microcontinent with Laurentia followed by slab break-off.

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Gayer, R. A., A. H. N. Rice, D. Roberts, C. Townsend, and A. Welbon. "Restoration of the Caledonian Baltoscandian margin from balanced cross-sections: the problem of excess continental crust." Transactions of the Royal Society of Edinburgh: Earth Sciences 78, no. 3 (1987): 197–217. http://dx.doi.org/10.1017/s026359330001110x.

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ABSTRACTConsideration of six balanced cross-sections through parts of the Finnmark Caledonides, N Norway indicates that shortening varies between 25% and 75%. A restored long cross-section across the width of the orogen, constructed with the aid of a branch line map, demonstrates a foreland propagating thrust system, with earlier formed more internal metamorphic nappes thrust SE 330 km under ductile conditions and then carried piggyback ESE a further 296 km on later brittle thrust sheets. Total shortening is 78·7% with a translation of the most internal thrust sheet of 626 km.The restored section suggests that: (1) the rate of propagation of deformation from hinterland to foreland is c. 2·27 cm y−1; (2) incorporation of basement into the nappes resulted from inversion of extensional faults formed during Iapetus rifting; (3) during rifting a Finnmark basement ridge separated a 220 km wide southeasterly Gaissa basin from the passive Iapetus continental margin which was at least 423 km wide; (4) the Finnmark Caledonides resulted from a continent-microcontinent collision which obducted continental crust at least 600 km across the Baltic margin; and (5) the Caledonian Baltoscandian margin prior to Iapetus suturing extended at least 400 km W of the Norwegian coast. On a Bullard reconstruction this overlaps with Laurentian rocks in Greenland. The excess continental crust is accounted for by shortening of the Baltoscandian margin during collision.

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Guntoro, Agus. "The effect of collision of the Banggai-Sula microcontinent to the tectonic development in Central Indonesian region." Bulletin of the Geological Society of Malaysia 43 (December 1, 1999): 103–11. http://dx.doi.org/10.7186/bgsm43199911.

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Paech, H. J. "Geotectonic setting of the Tertiary Uyandina and Indigirka-Zyryanka basins, Republic Sakha (Yakutia), Northeast Russia, using coal rank data." Stephan Mueller Special Publication Series 4 (September 17, 2009): 85–96. http://dx.doi.org/10.5194/smsps-4-85-2009.

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Abstract. Outcrops along the Inach River in the Uyandina basin and those along the Myatis' River in the Indigirka-Zyryanka basin were studied in detail and sampled for coal rank determinations. The Uyandina basin is an intramontane pull-apart basin characterized by extensional structures within the Moma rift system. The coal rank is below 0.3% vitrinite reflectance (Rr), which indicates shallow, immature conditions of basin formation and very low subsidence. The Myatis' River coal-bearing outcrops in the Indigirka-Zyryanka basin reveal compression induced by continent collision. The compressive deformation includes also lowermost Pliocene strata. Due to the position in the Verkhoyansk-Chersky fold belt adjacent to the Kolyma-Omolon microcontinent the Indigirka-Zyryanka basin has much in common with a foredeep, i.e. the asymmetry in thickness and tectonic structure. The vitrinite reflectance data (Rr) which range from 0.25% to more than 5% reinforce the accepted models that describe basin subsidence and geothermal history and the tectonic deformation.

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Polve, Mireille, Rene C. Maury, Philippe Vidal, Bambang Priadi, Herve Bellon, Rubini Soeria-Atmadja, Jean-Louis Joron, and Joseph Cotten. "Melting of lower continental crust in a young post-collision setting; a geochemical study of Plio-Quaternary acidic magmatism from central Sulawesi (Indonesia)." Bulletin de la Société Géologique de France 172, no. 3 (May 1, 2001): 333–42. http://dx.doi.org/10.2113/172.3.333.

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Abstract Acidic potassic calc-alkaline (CAK) magmas have been emplaced in the central part of the western arm of Sulawesi from 6.5 to 0.6 Ma, mostly as peraluminous dacites, rhyolites and granites. They overlay or crosscut a high-grade metamorphic basement including lower crustal garnet peridotites and granulites, the latter showing evidences for incipient melting during rapid uplift. Major and trace element data coupled with a Sr, Nd and Pb isotopic study of the CAK magmas and their lower crustal basement rocks demonstrate that they share a number of common features, including radiogenic Sr and Pb and unradiogenic Nd signatures, consistent with those of Australian granulites and Indian Ocean sediments. We propose that the CAK magmas derived from the anatexis of lower crustal rocks of Australian origin (the Banggai-Sula microcontinent) during the phase of uplift which followed their collision with the Sundaland margin (the western arm of Sulawesi) during the Middle Miocene, and possibly the breakoff of the subducted Molucca Sea slab.

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Keller, D. S., and J. J. Ague. "Quartz, mica, and amphibole exsolution from majoritic garnet reveals ultra-deep sediment subduction, Appalachian orogen." Science Advances 6, no. 11 (March 2020): eaay5178. http://dx.doi.org/10.1126/sciadv.aay5178.

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Diamond and coesite are classic indicators of ultrahigh-pressure (UHP; ≥100-kilometer depth) metamorphism, but they readily recrystallize during exhumation. Crystallographically oriented pyroxene and amphibole exsolution lamellae in garnet document decomposed supersilicic UHP majoritic garnet originally stable at diamond-grade conditions, but majoritic precursors have only been quantitatively demonstrated in mafic and ultramafic rocks. Moreover, controversy persists regarding which silicates majoritic garnet breakdown produces. We present a method for reconstructing precursor majoritic garnet chemistry in metasedimentary Appalachian gneisses containing garnets preserving concentric zones of crystallographically oriented lamellae including quartz, amphibole, and sodium phlogopite. We link this to novel quartz-garnet crystallographic orientation data. The results reveal majoritic precursors stable at ≥175-kilometer depth and that quartz and mica may exsolve from garnet. Large UHP terranes in the European Caledonides formed during collision of the paleocontinents Baltica and Laurentia; we demonstrate UHP metamorphism from the microcontinent-continent convergence characterizing the contiguous and coeval Appalachian orogen.

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Otsuki, Kenshiro. "Oblique subduction, collision of microcontinents and subduction of oceanic ridge: Their implications on the Cretaceous tectonics of Japan." Island Arc 1, no. 1 (August 1992): 51–63. http://dx.doi.org/10.1111/j.1440-1738.1992.tb00057.x.

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Boedo, F. L., A. P. Willner, G. I. Vujovich, and H. J. Massonne. "High-pressure/low-temperature metamorphism in the collision zone between the Chilenia and Cuyania microcontinents (western Precordillera, Argentina)." Journal of South American Earth Sciences 72 (December 2016): 227–40. http://dx.doi.org/10.1016/j.jsames.2016.09.009.

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Hajnal, Z., J. Lewry, D. White, K. Ashton, R. Clowes, M. Stauffer, I. Gyorfi, and E. Takacs. "The Sask Craton and Hearne Province margin: seismic reflection studies in the western Trans-Hudson Orogen." Canadian Journal of Earth Sciences 42, no. 4 (April 1, 2005): 403–19. http://dx.doi.org/10.1139/e05-026.

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A three-dimensional model of the regional crustal architecture of the western Trans-Hudson Orogen, based on the interpretation of 590 km of deep-sounding seismic reflection data and a comparable length of existing seismic reflection information, is presented. The seismic images identify the regional geometry of the basal detachment zone (Pelican thrust) that separates juvenile allochthonous terranes from the underlying Archean microcontinent (Sask craton). The Sask Craton is inferred to have a minimum spatial extent of over 100 000 km2 with an associated crustal root that extends for 200 km along strike. During terminal collision, complete convergence of the RaeHearne and Superior continental blocks was precluded by the presence of the Sask Craton, resulting in the preservation of anomalous amounts of oceanic and associated sedimentary juvenile material. Along regional tectonic strike, consistency of crustal structure across the RaeHearne margin Reindeer zone boundary is established. Several phases of tectonic development, including multistage subduction and continentcontinent collision, are inferred for the western margin of the orogen. A bright, shallow (23.5 s two-way traveltime) band of reflectivity (Wollaston Lake reflector) imaged over ~150 000 km2 area is inferred to be a large post-orogenic mafic intrusion. A highly reflective, well-defined and structurally disturbed Moho discontinuity is mapped throughout the western Trans-Hudson Orogen. The present-day crustal architecture of the western Trans-Hudson Orogen is described in terms of the tectonic evolution within the region.

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Fainstein, Roberto, Juvêncio De Deus Correia do Rosário, Helio Casimiro Guterres, Rui Pena dos Reis, and Luis Teófilo da Costa. "Coastal and offshore provinces of Timor-Leste — Geophysics exploration and drilling." Leading Edge 39, no. 8 (August 2020): 543–50. http://dx.doi.org/10.1190/tle39080543.1.

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Regional geophysics research provides for prospect assessment of Timor-Leste, part of the Southeast Asia Archipelago in a region embracing the Banda Arc, Timor Island, and the northwest Australia Gondwana continental margin edge. Timor Island is a microcontinent with several distinct tectonic provinces that developed initially by rifting and drifting away from the Australian Plate. A compressive convergence began in the Miocene whereby the continental edge of the large craton collided with the microcontinent, forming a subduction zone under the island. The bulk of Timor Island consists of a complex mélange of Tertiary, Cretaceous, Jurassic, Triassic, Permian, and volcanic features over a basal Gondwana craton. Toward the north, the offshore consists of a Tertiary minibasin facing the Banda Arc Archipelago, with volcanics interspersed onshore with the basal Gondwana pre-Permian. A prominent central overthrust nappe of Jurassic and younger layers makes up the mountains of Timor-Leste, terminating south against an accretionary wedge formed by this ongoing collision of Timor and Australia. The northern coast of the island is part of the Indonesian back arc, whereas the southern littoral onshore plus shallow waters are part of the accretionary prism. Deepwater provinces embrace the Timor Trough and the slope of the Australian continental margin being the most prospective region of Timor-Leste. Overall crust and mantle tectonic structuring of Timor-Leste is interpreted from seismic and potential field data, focusing mostly on its southern offshore geology where hydrocarbon prospectivity has been established with interpretation of regional seismic data and analyses of gravity, magnetic, and earthquake data. Well data tied to seismic provides focal points for stratigraphic correlation. Although all the known producing hydrocarbon reservoirs of the offshore are Jurassic sands, interpretation of Permian and Triassic stratigraphy provides knowledge for future prospect drilling risk assessment, both onshore and offshore.

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Prahastomi, Mochammad, Achmad Fahruddin, Lauti D.Santy, and Ryandi Adlan. "Depositional Facies Model and Reservoir Quality of Paleogene Limestone in Labengki Island, Southeast Sulawesi." Jurnal Geologi dan Sumberdaya Mineral 23, no. 3 (August 31, 2022): 189–96. http://dx.doi.org/10.33332/jgsm.geologi.v23i3.507.

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Eastern Indonesia has become an attractive venture for hydrocarbon exploration since 10 years ago. The discovery of hydrocarbon from Miocene carbonate of Tondo Formation has opened a new opportunity and hopes in the Southeast Sulawesi region. Can we find other potential reservoirs in Southeast Sulawesi? In this study, we assess and reconstruct the depositional model and the reservoir quality of the Paleogene Tampakura Formation in Labengki Island, Southeast Sulawesi. This field observation and petrographical study revealed that: (1) Tampakura Formation comprises mainly of grainstone, boundstone and floatstone with minor packstone and dolomitic wackestone/mudstone, (2) Tampakura Formation was deposited mainly in wide carbonate sand shoals and reef margin belt of rimmed carbonate shelf, (3) Boundstone and floatstone facies could be the best reservoir candidate in the region since they show extensive porosities development of cavernous and fracture porosity, (4) Dolomite cementation has deteriorated the reservoir quality of packstone which was deposited in platform interior-restricted marine, (5) Extensive calcite cementation in grainstone facies has reduced the reservoir quality of Tampakura Formation. However, locally, solution enlarged fracture porosity may have enhanced it. We suggest that post collision event of Late Oligocene - Early Miocene between Australian-originated microcontinent and ophiolite complex was highly responsible to create cavernous porosity. The collision resulted in the folding and uplifting of Tampakura Formation to the subaerial exposure. The carbonate strata were exposed to the surface developing a cavernous porosity and potentially becoming the best reservoir candidate for the next exploration target.Keywords: Carbonate facies, Kendari Basin, reservoir quality, Tampakura Formation.

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Rudnev, S. N., O. M. Turkina, V. G. Mal’kovets, E. A. Belousova, P. A. Serov, and V. Yu Kiseleva. "Intrusive Complexes of the Late Neoproterozoic Island Arc Structure of the Lake Zone (Mongolia): Isotope Systematics and Sources of Melts." Russian Geology and Geophysics 63, no. 1 (January 1, 2022): 23–38. http://dx.doi.org/10.2113/rgg20204252.

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Abstract –We present data on the geochemical and Sr–Nd isotope compositions of rocks and on the Lu–Hf isotope composition of magmatic and xenogenic zircons from granitoids and gabbroids of the late Neoproterozoic island arc structure of the Lake Zone. Plagiogranitoids, gabbroids, and quartz diorites (559–542 Ma) formed at the late Neoproterozoic subduction stage of magmatism, and two-feldspathic granites (~483 Ma) mark Cambrian–Ordovician accretion–collision processes. We have established that the volcanic rocks of the late Neoproterozoic island arc and/or its oceanic base, which formed from the depleted mantle, were the mafic source of plagiogranitoids. This is proved by the overlapping positive εNd values of plagiogranitoids and the host volcanic rocks and by the commensurate εHf values of magmatic zircons from the plagiogranitoids and depleted mantle. The lower εNd values of gabbro and quartz diorites from the Tavan Hayrhan and Shuthuyn plutons, the lower εHf values of zircons from these rocks, and the high (87Sr/86Sr)0 ratios and K2O, Rb, and Th contents point to the generation of these rocks from a less depleted mantle source, namely, mantle wedge peridotites. The isotope composition of the latter changed at the previous subduction stage under the impact of fluids and with the contribution of subducted sediments. The least radiogenic Hf isotope composition of magmatic and xenogenic zircons from Ordovician accretion–collisional two-feldspathic granites of the Ih Zamiin pluton suggests their formation through the melting of the late Neoproterozoic–Cambrian island arc crust with the contribution of more differentiated crustal sources enriched in Th, Nb, and LREE and characterized by low εNd values. The age of xenogenic zircons (≤716 Ma) in the studied granitoids and gabbroids and their similarity in Hf isotope composition to magmatic zircons from the same rocks confirm the formation of the late Neoproterozoic island arc of the Lake Zone in an intraoceanic setting far from ancient continental sources similar to the Dzavhan microcontinent.

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Gülyüz, Erhan, Nuretdin Kaymakci, Maud J. M. Meijers, Douwe J. J. van Hinsbergen, Côme Lefebvre, Reinoud L. M. Vissers, Bart W. H. Hendriks, and A. Ahmet Peynircioğlu. "Late Eocene evolution of the Çiçekdağı Basin (central Turkey): Syn-sedimentary compression during microcontinent–continent collision in central Anatolia." Tectonophysics 602 (August 2013): 286–99. http://dx.doi.org/10.1016/j.tecto.2012.07.003.

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Fedorov, Alexander, Valentina Makrygina, Anatoly Mazukabzov, Alexander Nepomnyashchikh, Dulmazhap Ayurzhanaeva, and Mariya Volkova. "Resources of quartz raw materials, Gargan block, East Sayan quartzite-bearing area." Georesursy 23, no. 4 (November 30, 2021): 96–106. http://dx.doi.org/10.18599/grs.2021.4.11.

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The evaluation (according to structural and geochemical rock properties ) of the quartzites from the East Sayan quartzite-bearing area as a potential source of quartz raw material for crystalline silicon and optical glass manufacturing can significantly expand the forecast resources of this type of raw materials. The geological structure of the Irkut Formation, productive of high-purity quartzites is specified within the Oka-Urik, Urengenur and Urdagargan quartz-bearing areas; geological, mineralogical-petrographic and geochemical characteristics of the main quartzite types are given, the main morphological features of productive high-purity quartzite bodies are specified to predict their occurrence at depth. The major factors in the formation of high-purity quartzite bodies include: 1) quartzites are accumulated in the siliceous-carbonate sequence of the Middle Riphean Irkut Formation within a broad but isolated basin; 2) high-purity quartzite bodies are produced as a result of dynamic recrystallization due to the deformation of primary microquartzites resulting from the collision of the Dunzhugar island arc with the Gargan microcontinent margin. Within the western part of the East-Sayan quartz-bearing area, quartzite reserves as a potential source for silicon metallurgy and production of optical glass were estimated as 134 mln tons.

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Shellnutt, J. G. "The enigmatic continental crust of North-Central Africa: Saharan Metacraton or Central Sahara Shield?" South African Journal of Geology 124, no. 2 (June 1, 2021): 383–90. http://dx.doi.org/10.25131/sajg.124.0047.

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Abstract The continental crust of North-Central Africa between the Tuareg and Arabian-Nubian shields and south to the Central African Orogenic Belt is enigmatic due to the few bedrock exposures especially within the central region. The current understanding, based on a review of geochronology and isotope geochemistry, is that the central Sahara region is a large, coherent craton that was ‘highly remobilized’ during the Late Neoproterozoic amalgamation of Gondwana and referred to as the Saharan Metacraton. However, new data from the Guéra, Ouaddaï, and Mayo Kebbi massifs and the Lake Fitri inlier of Chad suggest that it may be a composite terrane of older cratonic blocks or microcontinents with intervening Mesoproterozoic to Neoproterozoic domains and referred to as the ‘Central Sahara Shield’. It is postulated that the older crust and juvenile crust were sutured together along a Pan-Gondwana collisional belt (Central Sahara Belt) that bisects the central Sahara region. The ‘Central Sahara Shield’ hypothesis suggests the Chad Lineament, a narrow arcuate gravity anomaly within central Chad, could be a collisional belt suture zone and that it may explain the existence of the relatively juvenile crust that typifies southern and eastern Chad. The new data improves upon the existing knowledge and challenges the lithotectonic paradigm of the Saharan Metacraton. Further investigations are required to fully characterize the crust of the central Sahara region and to test the contrasting hypotheses.

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Willner, Arne P., Colombo C. G. Tassinari, José F. Rodrigues, Jorge Acosta, Ricardo Castroviejo, and Miguel Rivera. "Contrasting Ordovician high- and low-pressure metamorphism related to a microcontinent-arc collision in the Eastern Cordillera of Perú (Tarma province)." Journal of South American Earth Sciences 54 (October 2014): 71–81. http://dx.doi.org/10.1016/j.jsames.2014.05.001.

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Saadre, Tõnis, Rein Einasto, and Svend Stouge. "Ordovician stratigraphy of the Kovel-1 well (Volkhov–Haljala) in the Volynia region, northwestern Ukraine." Bulletin of the Geological Society of Denmark 51 (October 20, 2004): 47–69. http://dx.doi.org/10.37570/bgsd-2004-51-04.

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The Ordovician succession of the Kovel-1 well in the Volynia region, northwestern Ukraine is composed of a basal 0.6 m thick siliciclastic unit succeeded by 24.7 m Lower and lower Middle Ordovician carbonate sediments. The carbonate rocks are divided into 13 informal lithologic units. The carbonate sediments accumulated in marine shallow water open shelf and shoal or turbulent environs. Biostratigraphically, the succession is referred to seven chitinozoan zones and 12 conodont biozones. Integration, chronostratigraphic position and correlation of the proposed biozones with those from Baltoscandia are briefly discussed. Four major unconformities are recognized within the succession: 1) the Pakerort(?)–Volkhov unconformity, 2) the mid Volkhov unconformity, 3) the early Kunda unconformity and 4) the early Mid Ordovician hiatus. The latter straddles the Oeland–Viru regional Series boundary in the well. The early Mid Ordovician unconformity is prominent and the corresponding hiatus spans the Aseri and Lasnamägi regional stages (= upper Darriwilian). A complex of cyclic transgressive–regressive depositional pattern prevailed and the whole succession is referred to three major depositional cycles. The major depositional cycles are related to global eustatic sea-level cycles in general and hypothetic way to tectonic events caused by collisions of Peri-Gondwanan microcontinents with Baltica.

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Shatsky, V. S., A. L. Ragozin, S. Yu Skuzovatov, O. A. Kozmenko, and E. Yagoutz. "Isotope-Geochemical Evidence of the Nature of the Protoliths of Diamondiferous Rocks of the Kokchetav Subduction–Collision Zone (Northern Kazakhstan)." Russian Geology and Geophysics 62, no. 5 (May 1, 2021): 547–56. http://dx.doi.org/10.2113/rgg20204278.

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Abstract —The isotope-geochemical features of diamondiferous metamorphic rocks of the Kokchetav subduction–collision zone (KSCZ) show that both the basement rocks and the sediments of the Kokchetav massif were their protoliths. A whole-rock Sm–Nd isochron from the diamondiferous calc-silicate, garnet–pyroxene rocks and migmatized granite-gneisses of the western block of the KSCZ yielded an age of 1116 ± 14 Ma, while an age of 1.2–1.1 Ga was obtained by U–Pb dating of zircons from the granite-gneiss basement of the Kokchetav microcontinent. Based on these data, we assume that the protoliths of the calc-silicate, garnet–pyroxene rocks and the granite-gneisses of the KSCZ were the basement rocks sharing an initially single Nd source, which was not influenced by high- to ultrahigh-pressure metamorphism (~530 Ma). Therefore, their geochemical features are probably not directly related to ultrahigh-pressure metamorphism. The corresponding rock associations lack isotope-geochemical evidence of partial melting that would occur during ultrahigh-pressure metamorphism, which suggesting that they were metamorphosed under granulite-facies conditions. At the same time, the high-alumina diamondiferous rocks of the Barchi area (garnet–kyanite–mica schists and granofelses), which were depleted to different degrees in light rare-earth elements (REE) and K, have yielded a Sm–Nd whole-rock isochron age of 507 ± 10 Ma indicating partial melting of these rocks during their exhumation stage. The close ɛNd (1100) values of the basement rocks and garnet–kyanite–mica schist with geochemical characteristics arguing against its depletion during high-pressure metamorphism indicate that the basement rocks were a crustal source for high-alumina sediments.

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Acef, Kaissa, Jean Paul Liégeois, Aziouz Ouabadi, and Louis Latouche. "The Anfeg post-collisional Pan-African high-K calc-alkaline batholith (Central Hoggar, Algeria), result of the LATEA microcontinent metacratonization." Journal of African Earth Sciences 37, no. 3-4 (October 2003): 295–311. http://dx.doi.org/10.1016/j.jafrearsci.2003.10.001.

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LORENZ, HENNING, DAVID G. GEE, and MARTIN J. WHITEHOUSE. "New geochronological data on Palaeozoic igneous activity and deformation in the Severnaya Zemlya Archipelago, Russia, and implications for the development of the Eurasian Arctic margin." Geological Magazine 144, no. 1 (November 9, 2006): 105–25. http://dx.doi.org/10.1017/s001675680600272x.

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The Severnaya Zemlya Archipelago, located close to the continental edge of the Kara Shelf in the Russian high Arctic, represents, together with northern Tajmyr, the exposed Neoproterozoic and Palaeozoic part of the North Kara Terrane. This terrane has been interpreted as an independent microcontinent or part of a larger entity, such as Arctida or Baltica, prior to collision with Siberia in Late Carboniferous time. A major stratigraphic break, the Kan'on (canyon) River Unconformity, separates folded Late Cambrian from Early Ordovician successions in one area, October Revolution Island. New geochronological U–Th–Pb ion-microprobe data on volcanic and intrusive rocks from this island constrain the age of an important magmatic episode in the earliest Ordovician. A tuff, in association with Tremadocian fossils, overlying the Kan'on River Unconformity, has been dated to 489.5 ± 2.7 Ma. The youngest rocks beneath the unconformity are of the Peltura minor Zone, and the latter has been dated previously, in western Avalonia, to 490.1+1.7−0.9 Ma. Thus, little time is available for the tectonic episode recorded by the unconformity, and the similarities in radiometric dates may indicate problems with the correlation of faunal markers for the Cambrian–Ordovician boundary across palaeo-continents. The other extrusive and intrusive rocks which have been related to Early Ordovician rifting in the Severnaya Zemlya area yield ages from 489 Ma to 475 Ma. An undeformed granite, cutting folded Neoproterozoic successions on neighbouring Bol'shevik Island has been dated to 342 ± 3.6 Ma and 343.5 ± 4.1 Ma (Early Carboniferous), in accord with evidence elsewhere of Carboniferous strata unconformably overlying the folded older successions. This evidence conflicts with the common interpretation that the structure of the Severnaya Zemlya Archipelago originated during the collision of the North Kara Terrane with Siberia in Late Carboniferous time. An alternative interpretation is that Severnaya Zemlya was located in the Baltica foreland of the Caledonide Orogen and that the eastward-migrating deformation of the foreland basin reached the area of the archipelago in latest Devonian to Early Carboniferous time. This affinity of the North Kara Terrane to Baltica is further supported by 540–560 Ma xenocrysts in Ordovician intrusions on October Revolution Island, an age which is characteristic of the Timanide margin of Baltica.

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Journal articles on the topic 'Microcontinental collision'

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