Palaeoproterozoic Evolution Research Articles

Deep crustal structure and Palaeoproterozoic evolution of the supercontinent Lauroscandia: 3D model of Trans-Hudson Orogen and new insight based on LITHOPROBE, FIRE and 1-EU reflection seismic and HuBLE tomography imaging

The Palaeoproterozoic Lauroscandia supercontinent received fundamental geological and geodynamic support based on the 3D characteristics of the deep structure of key tectonic units in the North American and East European megacratons. The deep structure of the western Reindeer zone of Trans-Hudson orogen (THO) most closely resembles the structure of sedimentary–volcanic belts along the eastern boundary of the Karelia craton formed during continental rifting. These belts were accompanied by vast depressions filled by the thick epicontinental volcano-sedimentary sequences, which were later affected together with the Archaean basement by high-temperature metamorphism. Some of the rifts could later be transformed into narrow short-lived oceans. The deep structure of the eastern Reindeer zone of THO is similar to Svecofennian accretionary orogen: structures of the crust and crust-mantle boundary point to a significant breakup of the continent, the origin of an ocean, and its later closure, involving a number of subduction zones, which operated almost simultaneously. The Sask craton should be viewed as a fragment of a Neoarchaean megacraton of North America. The main feature of the THO, Svecofennian Accretionary Orogen and Lauroscandia as a whole during Palaeoproterozoic evolution is the causal link with development of the Hudson Bay superplume that initialized a succession of huge events of plate-tectonic type. The head of the Hudson Bay superplume reached about 3000 km in the north-south direction and from 3000 to 4500 km in the east-west direction at different stages of evolution; 4500 km likely is a minimal estimate of the greatest dimension. The width of the Manikewan ocean reached more 1000 km, the width of the Svecofennian–Pre-Labradorian Ocean of ~2000 km that apparently also corresponds to a minimal value. The most significant temporal intervals in the Lauroscandia Palaeoproterozoic evolution (~2.5 Ga and 2.2–1.8 Ga ago) coincide with events of global rank.

Zircon U-Pb and Lu-Hf record from high-grade complexes within the Mantiqueira Complex: First evidence of juvenile crustal input at 2.4–2.2 Ga and implications for the Palaeoproterozoic evolution of the São Francisco Craton

The Mantiqueira Complex together with the Mineiro Belt and Juiz de Fora Complex, characterize a long-lived system of oceanic and continental magmatic arcs. The proposed accretion of these terranes in the Rhyacian resulted in the closure of the Minas Basin, a fundamental turning point for the geology of this area. Understanding this event is critical for determining the evolution of the South American continent. Despite its importance, there is a paucity of zircon U-Pb and Lu-Hf data available for the Mantiqueira Complex and no data from two complexes within the later.U-Pb zircon data were obtained from interpreted metasediments of those two complexes, the granulite facies Acaiaca Complex and Pedra Dourada Granulite. Four targeted samples yield cores with ages between 3.5 and 2.2 Ga and a large proportion of metamorphic grains and rims at ca. 2.1–2.0 Ga. The similarity between the detrital zircon signatures of the Acaiaca Complex and Pedra Dourada Granulite, and the Archaean inheritance of the Mantiqueira Complex, indicates that these three units are related. Potentially the Acaiaca Complex and Pedra Dourada Granulite either sourced the Mantiqueira Complex or the Mantiqueira intrusive suites reworked the protoliths of the Acaiaca Complex and Pedra Dourada Granulite.Hf-in-zircon data indicate two discrete sources for both the Acaiaca Complex and Pedra Dourada Granulite. An Archaean source (model ages of 3.2–2.6 Ga), which is consistent with the suggested origin of the Mantiqueira Complex as recycled Archaean crust sourced from the São Francisco Craton and reworked during the ca. 2.1 Ga Transamazonian orogeny. A second more juvenile source (model ages of 2.4–2.2 Ga) recorded exclusively within the more mafic samples is identical in age and Hf to that found in the Juiz de Fora Complex. This could indicate a close link between the Mantiqueira and Juiz de Fora Complexes in the period 2.2 to 2.0 Ga. Alternatively, these juvenile zircons may represent an as yet unidentified juvenile portion of the Mantiqueira arc.The results of this study are consistent with the prevailing theories for formation of the Mantiqueira Complex as a continental arc with cumulative proportion curves indicating an active-margin type depositional setting.

3D model of Svecofennian Accretionary Orogen and Karelia Craton based on geology, reflection seismics, magnetotellurics and density modelling: Geodynamic speculations

A 3D model of deep crustal structure of the Archaean Karelia Craton and late Palaeoproterozoic Svecofennian Accretionary Orogen including the boundary zone is presented. The model is based on the combination of data from geological mapping and reflection seismic studies, along profiles 1-EU, 4B, FIRE-1-2a-2 and FIRE-3-3a, and uses results of magnetotelluric soundings in southern Finland and northern Karelia. A seismogeological model of the crust and crust–mantle boundary is compared with a model of subhorizontal velocity-density layering of the crust. The TTG-type crust of the Palaeoarchaean and Mesoarchaean microcontinents within the Karelia Craton and the Belomorian Province are separated by gently dipping greenstone belts, at least some of which are palaeosutures. The structure of the crust was determined mainly by Palaeoproterozoic tectonism in the intra-continental settings modified by a strong collisional compression at the end of the Palaeoproterozoic. New insights into structure, origin and evolution of the Svecofennian Orogen are provided. The accretionary complex is characterized by inclined tectonic layering: the tectonic sheets, ~15 ​km thick, are composed of volcanic-sedimentary rocks, including electro-conductive graphite-bearing sedimentary rocks, and electro-resistive granitoids, which plunge monotonously and consecutively eastward. Upon reaching the level of the lower crust, the tectonic sheets of the accretionary complex lose their distinct outlines. In the seismic reflection pattern they are replaced by a uniform acoustically translucent medium, where separate sheets can only be traced fragmentarily. The crust–mantle boundary bears a diffuse character: the transition from crust to mantle is recorded by the disappearance of the vaguely drawn boundaries of the tectonic sheets and in the gradual transition of acoustically homogeneous and translucent lower crust into transparent mantle. Under the effect of endogenic heat flow, the accretionary complex underwent high-temperature metamorphism and partial melting. Blurring of the rock contacts, which in the initial state created contrasts of acoustic impedance, was caused by partial melting and mixing of melts. The 3D model is used as a starting point for the evolutionary model of the Svecofennian Accretionary Orogen and for determination of its place in the history of the Palaeoproterozoic Lauro-Russian intracontinental orogeny, which encompassed a predominant part of the territory of Lauroscandia, a palaeocontinent combining North American and East European cratons. The model includes three stages in the evolution of the Lauro-Russian Orogen (~2.5, 2.2–2.1 and 1.95–1.87 ​Ga). The main feature of the Palaeoproterozoic evolution of the accretionary Svecofennian Orogen and Lauroscandia as a whole lay in the causal link with evolution of a superplume, which initiated plate-tectonic events. The Svecofennian–Pre-Labradorian palaeo-ocean originated in the superplume axial zone; the accretionary orogens were formed along both continental margins due to closure of the palaeo-ocean.

Late Palaeoproterozoic evolution of the buried northern Gawler Craton

This study utilises U-Pb geochronology, Lu-Hf, Sm-Nd isotopes and geochemistry to constrain the timing of deposition, metamorphism and provenance characteristics of buried Palaeoproterozoic meta-sedimentary and meta-igneous rocks in the northern Gawler Craton, Australia. The data suggest that sedimentary sequences were deposited between ca. 1780 and 1740Ma across a wide region accompanied by syn-depositional magmatism. Restricted zircon age spectra, relatively radiogenic whole-rock Hf-Nd and in-situ zircon Hf isotopic compositions and enriched REE signatures support the notion of a connected series of basins or a single large basin, which developed on a common Neoarchaean substrate across the northern Gawler Craton during the Late Palaeoproterozoic. Temporal and isotopic correlation of these indurated rocks with Palaeoproterozoic basins throughout the North Australian Craton suggests they may form part of an extensive basin system that developed across the Australian continent during the Late Palaeoproterozoic. The meta-sedimentary and meta-igneous rocks of the northern Gawler Craton record high-grade crustal anatexis during the ca. 1730–1690Ma Kimban Orogeny and subsequent Early Mesoproterozoic re-working.

Geochemistry and geochronology of orthogneisses in Bode Saadu area, southwestern Nigeria and their implications for the Palaeoproterozoic evolution of the area

Bode Saadu area, southwestern Nigeria is underlain by metasedimentary and metaigneous rocks including orthogneisses which have been intruded by largely undeformed granitic rocks of probable Pan-African (ca. 600Ma) age. The metamorphic rocks have been subjected to several phases of both ductile and brittle deformation. Three suites of orthogneisses of granodioritic composition have been identified in the area, locally they contain xenoliths of metasediments. Geochemical analyses show that they are calc-alkaline, magnesian, metaluminous and possess the characteristics of granitoids emplaced in magmatic arcs.LA-ICP-MS in-situ dating of zircons in these orthogneisses has yielded upper Concordia intercept Palaeoproterozoic ages of 2236±29Ma, 2228±32Ma and 2179±28Ma. These indicate the times of crystallization of these rocks and attest to a long period of magmatism associated with the Eburnean orogeny in this part of Nigeria. The gneisses bear the imprints of several deformation events in the form of foliations, folds and shear zones. The geochronological data enable constraints to be placed on the timing of the development of some of these structures and also indicate that some of the metasedimentary units are at least of Palaeoproterozoic age.Similar Palaeoproterozoic orthogneisses have been documented in some other parts of southwestern Nigeria, in Central Hoggar area of the Tuareg Shield and in the Borborema Province of Brazil and support their correlation as part of West Gondwana.

New U–Pb SHRIMP ages from the Lubango region, SW Angola: insights into the Palaeoproterozoic evolution of the Angolan Shield, southern Congo Craton, Africa

In an attempt to better understand the tectonic evolution of the continental crust forming SW Angola, zircon grains from the principal Precambrian rock types exposed in the Lubango area have been analysed using the sensitive high-resolution ion microprobe method. U–Pb ages of 2038 ± 28 Ma and 1954 ± 6 Ma were obtained on weakly deformed granite samples from the basement below the Humpata Plateau. The Chela Group on the Humpata Plateau is a relatively undeformed Palaeoproterozoic supracrustal sequence with an eruptive age of 1798 ± 11 Ma on ignimbrite of the Humpata Formation. The age of the northern part of the Kunene Complex is constrained by zircon data from a xenolith of basement gneiss and a mangerite dyke cutting anorthosite, which give an emplacement age of 1385 ± 7 Ma. The c . 2.0 Ga granites below the Chela Group are part of a Palaeoproterozoic granitoid terrane that extends from north of Lubango in Angola into NW Namibia. This terrane is referred to as the Angolan Shield. Regionally, the Angolan Shield is interpreted to be part of a Palaeoproterozoic magmatic arc that extends NE from Angola and Namibia under Phanerozoic cover into NW Zambia. The resultant crustal terrane defined the southern margin of the developing Congo Craton at c . 2.0 ± 0.04 Ga. Supplementary materials: Tables summarizing the zircon U–Pb data are available at www.geolsoc.org.uk/SUP18577 .

Major early thrusting as a control on the Palaeoproterozoic evolution of the Lewisian Complex: evidence from the Outer Hebrides, NW Scotland

New structural, metamorphic and geochronological data suggest that the Lewisian Complex of the Outer Hebrides can be interpreted as a Proterozoic orogen in which a thrust sheet of juvenile arc material was driven over Archaean gneisses at an early stage. Incubation and loading of the underlying Archaean gneisses triggered prograde metamorphism and extensive ductile deformation with a strong gravitational flattening component combined with top-to-the-WNW transport. Large shear zones developed at this time are of local importance, but are not fundamental structural boundaries. The recognition of early orogenic thrusting followed by extensive ductile deformation shows a close resemblance to the sequence of events recognized within the Nagssugtoqidian orogen, with which the Lewisian Complex is correlated. As in the Nagssugtoqidian orogen, younger penetrative ductile deformation often masks the major structural boundaries formed by older thrusts. Supplementary material: Detailed structural and lithological maps of the Langavat Belt, and geochronological data and analytical methods description are available at www.geolsoc.org.uk/SUP18515 .

Palaeoproterozoic evolution of the Killi Killi Formation and orogenic gold mineralization in the Granites–Tanami Orogen, Western Australia

The Palaeoproterozoic Killi Killi Formation is a succession of turbiditic sedimentary rocks in the Granites–Tanami Orogen of Western Australia and the Northern Territory. SHRIMP U–Pb data from zircons in the Killi Killi Formation in Western Australia indicate that these rocks could be as old as ca. 1864 Ma and about 30 million years older than the previously proposed ages for the formation. A petrological and geochemical study shows that these rocks: 1) have an igneous source; and 2) based on comparisons with modern analogues, were deposited in an active continental margin. These findings also confirm that the Coyote deposit in the Western Australian portion of the Granites–Tanami Orogen is a typical orogenic gold deposit of Palaeoproterozoic association. Basin deposition culminated by ca. 1850 Ma, followed by inversion and collisional tectonics at ca. 1800 Ma, giving rise to widespread formation of orogenic lode-gold deposits throughout the Granites–Tanami Orogen at the time that the Granite–Tanami Orogen collided with the Arunta Orogen to the south.

A revised Palaeoproterozoic chronostratigraphy for the Pine Creek Orogen, northern Australia: Evidence from SHRIMP U–Pb zircon geochronology

New SHRIMP U–Pb zircon geochronology for volcanic and volcaniclastic sedimentary rocks from the central Pine Creek Orogen provides constraints on the Palaeoproterozoic evolution of northern Australia. An intermediate agglomerate from the Stag Creek Volcanics (Namoona Group) and two samples of volcaniclastic sedimentary rock from the Wildman Siltstone (Mount Partridge Group) were dated to constrain the age of the lower parts of the Palaeoproterozoic succession. These samples all have a youngest zircon population with an age in the range ca. 2030–2020 Ma, which is interpreted to approximate the age of volcanism and volcaniclastic deposition. Two widely separated samples of Gerowie Tuff from the overlying South Alligator Group have depositional ages of 1864 ± 3 Ma and 1862 ± 4 Ma. Zircons of the Berinka Volcanics and Warrs Volcanic Member within the overlying Finniss River Group have crystallisation ages of 1861 ± 4 Ma and 1862 ± 3 Ma, respectively. These new data suggest that the basal units of the Pine Creek Orogen were being deposited in part during a previously unrecognised episode of ca. 2030–2020 Ma felsic volcanism and sedimentation in northern Australia, which was followed by a major hiatus. The ca. 1865–1860 Ma ages for volcanic rocks within the South Alligator and Finniss River Groups provide a maximum age on the timing of deformation and metamorphism in the central Pine Creek Orogen, and allow correlation with felsic volcanic events across large areas of the Pine Creek Orogen and the North Australian Craton.

The Palaeoproterozoic evolution of the Litchfield Province, western Pine Creek Orogen, northern Australia: Insight from SHRIMP U–Pb zircon and in situ monazite geochronology

The Litchfield Province, located on the western margin of the Palaeoproterozoic Pine Creek Orogen, northern Australia, comprises variably metamorphosed pelitic and psammitic sediments, extensively intruded by voluminous granitoids and mafic rocks. SHRIMP U–Pb in situ monazite geochronology of undeformed granulite-facies migmatitic Hermit Creek Metamorphics (ca. 730 °C, ca. 5 kb) and mid-amphibolite-facies Fog Bay Metamorphics (ca. 600 °C, ca. 4 kb) indicates mid- to high-grade metamorphism affected these rocks at ca. 1855 Ma. SHRIMP U–Pb analysis on low Th/U metamorphic zircon rims from the Fog Bay Metamorphics also indicate metamorphism at ca. 1855 Ma. The undeformed nature of the Hermit Creek and Fog Bay Metamorphics suggest that metamorphism was not accompanied by significant penetrative strain. These observations suggest that the elevated geotherm at this time may have been due to conductive and advective thermal input within a thinned lithosphere during intra-crustal extension and rifting. Metamorphism at ca. 1855 Ma in the Litchfield Province is similar in age to that reported from the Hooper Orogen and the Western and Central Zones of the Halls Creek Orogen, but not with the Eastern Zone. Furthermore, there appears no evidence for the ca. 1845–1835 Ma Halls Creek Orogeny in the Litchfield Province, suggesting that the inferred suture in the Halls Creek Orogen between the Kimberley Craton and the proto North Australian Craton, may not extend into the Litchfield Province and that the Litchfield Province may have been contiguous with, or forms part of, the Kimberley Craton. The upper-amphibolite-facies Welltree Metamorphics (ca. 700 °C, ca. 4 kb), in contrast, preserve monazite grains that are aligned with a penetrative biotite fabric and are dated at 1813 ± 3 Ma, thus recording a previously unrecognised tectono-thermal event in the Pine Creek Orogen.

Geodynamic setting of the Birimian volcanism in central Ivory Coast (western Africa) and its place in the Palaeoproterozoic evolution of the Man Shield

AbstractPalaeoproterozoic volcanic formations having different geochemical features are described in the Katiola-Marabadiassa area (Central Ivory Coast). They consist of (i) metamorphic mafic rocks belonging to the greenstone belts, (ii) rhyodacites intruded into the greenstone belts and interpreted as sub-volcanic apophyses of TTG plutons, and (iii) calc-alkaline andesitic lava interbedded in the lower sedimentary pile of the Bandama Basin. The greenstone belt rocks have a magmatic signature of ocean floor tholeiites. They were generated from moderate partial melting of a fairly depleted spinel lherzolite source. The rhyodacites show the same compositions as the TTG granitoids of the belt. These TTGs generated from melting of garnet-bearing amphibolite, derived from subducted oceanic crust, but also from peridotite melting of the fertilized mantle wedge. The andesites show a common composition of active continental margin potassic calc-alkaline lavas. However, they do not constitute a volcanic belt, but belong to an intracontinental basin settled in a wrench tectonic system. They probably generated from remelting of sub-crustal metasomatised mantle.The tectono-magmatism story of the Katiola-Marabadiassa area comprises four stages. A similar evolution is found in other belt-and-basin areas in Ivory Coast. A review of lithostratigraphic and chronological data of the Birimian terrains leads us to compare the four-stage model of the Central Ivory Coast to the West-African Palaeoproterozoic evolution. The first stage corresponds to ocean crust formation, by mid-ocean ridge accretion and volcanic arc building. The second stage, partly overlapping the previous one, is convergent and lasted from oceanic crust stacking to TTG and associated greenstone belt formation. It led to a protocontinental crust accretion by docking of granitized blocks, from ca 2200 Ma to 2110 Ma. The third stage corresponds to the formation of intracontinental basins by reorganization of the granitoid-greenstone shields and of the remnant oceanic basins, between 2118 Ma and 2093 Ma. It was associated with calc-alkaline magma production. The fourth stage is characterized by transtensional stress, with the closure of the basins by left-lateral wrenching along N-S faults, and by emplacement of new potassic granitoids until 2072 Ma.

The Svecofennian orogen: a collage of microcontinents and island arcs

Abstract Based on an integrated study of geological and geophysical data, a tectonic model for the Palaeoproterozoic evolution of the Svecofennian orogen within the Fennoscandian Shield at the northwestern corner of the East European Craton is proposed. The Svecofennian orogen is suggested to have formed during five, partly overlapping, orogenies: Lapland-Savo, Lapland-Kola, Fennian, Nordic and Svecobaltic. The Svecofennian orogen evolved in four major stages, involving microcontinent accretion (1.92-1.88 Ga), large-scale extension of the accreted crust (1.87-1.84 Ga), continent-continent collision (1.87-1.79 Ga) and finally gravitational collapse (1.79 and 1.77 Ga). The stages partly overlapped in time and space, as different processes operated simultaneously in different parts of the plates. In the Lapland-Savo and Fennian orogenies, microcontinents (suspect terranes) and island arcs were accreted to the Karelian microcontinent, which itself was accreting to Laurentia in the Lapland-Kola orogeny. The formation of the Svecofennian orogen was finalized in two continental collisions producing the Nordic orogen in the west (Fennoscandia-Amazonia) and Svecobaltic orogen in the SSW (Fennoscandia- Sarmatia). The collisions were immediately followed by gravitational collapse.

Late Archaean to Palaeoproterozoic evolution of the Trans-North China Orogen: insights from synthesis of existing data from the Hengshan-Wutai-Fuping belt

Abstract The Hengshan-Wutai-Fuping mountain belt constitutes the middle segment of the Trans-North China Orogen, which separates the North China Craton into the Eastern and Western Blocks. The belt consists of the high-grade Hengshan and Fuping complexes, and the intervening low- to medium-grade Wutai Complex. Previous tectonic models assumed that the high-grade complexes were an older basement (Archaean to Palaeoproterozoic) to the low-grade Wutai Complex. However, new geochronological data show that the emplacement of granitoid rocks and eruption of volcanic rocks in the Wutai Complex occurred essentially coeval with or slightly earlier than intrusion of the tonalitic-trondhjemitic-granodioritic (TTG) suites in the Hengshan and Fuping complexes. New isotopic data also reveal the widespread presence of Palaeoproterozoic granitoid rocks in these complexes. Structural and metamorphic data demonstrate similar tectonothermal histories for the three complexes, which are characterized by peak medium- to high-pressure metamorphism accompanied by the development of thrusting, isoclinal folding (F 2 ) and penetrative foliations, followed by near-isothermal decompression and cooling and retrogression associated with the formation of large-scale ductile shear zones and asymmetrical folds (F 3 ) with nearly vertical axial planes. These geochronological, structural and metamorphic data suggest that the tectonic evolution of the Hengshan-Wutai-Fuping mountain belt may not be related to local interaction of the three complexes, as suggested in earlier models, either through closure of a Wutai rift or collision between a Wutai arc and the Hengshan and Fuping micro-continental blocks. Instead, they may represent elements of a single Late Archaean to Early Palaeoproterozoic magmatic arc that was subsequently incorporated into the Trans-North China Orogen along which the Eastern and Western blocks amalgamated to form the North China Craton at around 1.85 Ga.

Palaeoproterozoic Evolution of the Lewisian Complex in South Harris, NW Scotland: Evidence from High-Grade Metamorphic Rocks

Palaeoproterozoic Evolution of the Lewisian Complex in South Harris, NW Scotland: Evidence from High-Grade Metamorphic Rocks

U-Pb ages of plutonic and volcanic rocks in the Svecofennian Bothnian Basin, central Sweden, and their implications for the Palaeoproterozoic evolution of the Basin

New U-Pb age data on two early orogenic granodiorites (ca. 1930 Ma) and one felsic metavolcanite (1870 Ma) from the Svecofennian Bothnian Basin area of central Sweden are presented. Combined with literature data they suggest an extended, at least ca. 80 m.y. long, evolution of this part of the Bothnian Basin. Sedimentation started before 1950 Ma, and continued up to at least 1870 Ma. Early-orogenic plutonic activity started at ca. 1950 Ma, perhaps even earlier, and continued up to ca. 1850-1840 Ma. Detrital zircons found in low-grade greywackes of the region range in age from ca. 1880 to 2020 Ma. According to the tentative model suggested here, these zircons may emanate from granitoids intruded into the greywacke sequence of the Bothnian Basin. They were subsequently exposed to erosion and included in upper parts of the sedimentary column. These upper parts could (statistically) be of a lower metamorphic grade than older greywackes, which are generally migmatized.

Ridge-trench interactions and high- T -low- P metamorphism, with particular reference to the Cretaceous evolution of the Japanese Islands

Abstract A corollary of plate tectonics is that spreading ridges ultimately interact with trenches; this is a consequence of the closure phase of the Wilson cycle that eliminates ocean basins. Ridge-trench interactions generate distinctive igneous, metamorphic, structural and sedimentation effects, which commonly are diachronous parallel to the trench; effects vary with plate boundary geometry and rate of migration is controlled by relative motion vectors. Identification of such interactions in the geological record is uncommon, which suggests that geological events triggered by ridge-trench interactions are attributed to other phenomena, such as changes in plate motion or a singularity at the trench. The estimated greater length of plate boundaries in the past means that subduction of a spreading ridge system could have been more common earlier in Earth history. High- T -low- P metamorphism requires a tectonic setting that allows enhanced heat flux, transient advection of heat due to magma ascent, unusually large internally generated heat, or some combination of these features. Subduction of a spreading ridge system produces anomalously high temperatures at shallow crustal depth through the development of a slab window, which allows transfer of sub-slab asthenospheric mantle across the slab to create an enhanced heat flux beneath the overriding plate. This process is important along convergent margins that develop a subduction-accretion complex, and drives low P/T ratio metamorphism and anatexis of the complex. Heat transport occurs by rising magma near the trench, which leads to formation of plutons with characteristic contaminated MORB geochemistry. Near-trench igneous activity and low P/T ratio metamorphism are the most striking features attributable to spreading ridge subduction and slab window formation, and together are likely to be diagnostic of ridge-trench interactions. Geological features of the Cretaceous Ryoke and Abukuma high- T -low- P metamorphic belts in Japan are consistent with the expectations of ridge subduction and slab window formation. Based on modelled plate interactions in the North Pacific Ocean basin during the Cretaceous, a tectonic scenario is presented for the evolution of the Japanese Islands that involves interactions between the Farallon-Izanagi ridge and a trench along the Asian continental margin. Other low P/T ratio metamorphic belts that owe their high- T lineage to interactions between spreading ridges and trenches are the Shimanto and Hidaka belts of Japan, and the Chugach belt of Alaska, USA. The complex tectonic evolution of Palaeozoic orogenic belts such as the Appalachian orogen of eastern Canada and USA, implies that ridge-trench interactions were involved in their evolution, although terminal continental collision makes the effects of these interactions difficult to identify in the geological record. There are many older belts for which ridge subduction and slab window formation should be evaluated, including the Palaeoproterozoic evolution of the Arunta Inlier, Australia, and the late Archean evolution of the Slave Province, northern Canada.