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Showing papers on "Gondwana published in 1989"


Book
01 Jan 1989
TL;DR: In this paper, the effect of global sea level cycles on tectonic evolution is investigated. But the authors focus on the geology of the Banda Sea and not on the seafloor of the Indian Ocean.
Abstract: Late mesozoic and cainozoic tectonic features - Wallace's line and its meaning, oceanic crust of the Indian Ocean and marginal seas, the Bengal and Nicobar abyssal fans, gravity measurements, active plate margins, Molucca Sea collision zone, Banda Sea, collision between the Australian continent and the Banda arc, Sunda arc-trench system, the main continental plates and microcontinents cainozoic sedimentary basins - classification, effect of global sea level cycles, tertiary basins in Borneo, basins of the Sunda Shelf and Gulf of Thailand, phillipine archipelago, eastern Indonesia phanerozoic tectonic framework - tectono-strtigraphic evolution, palinspastic reconstructions terrains of Cathaysian affinity - palaegeographic position of Cathaysia, North Vietnam complec suture fault zone, Indosinia block, the phanerozoic sedimentary cover of Indosinia, West Borneo basement block Gondwana affinity terrains - the Tibet plateau, the Himalayan tectonic terrain, post-glacial Gondwanas, Sinoburmalaya, Precambrian basement, Machinchano-Tarutau-Moloheim formations, ordovician platform, Silurian, carboniferous diamictite belt ophiolites and sutures the great Sunda-Pacific volcanic arcs - Gandise arc of the Indus-Zangbo-Yarlung system, Burma-Andaman Sea sector, Indonesia, Borneo, Philippines, Taiwan, Ryukyu arc granite and associated plutonic rocks - Tibet, Sanjiang fold system of western Yunnan, south-eastern China, Indochina region, Sundaland granite belts.

608 citations


Journal ArticleDOI
01 Apr 1989-Geology
TL;DR: A vast region of upper Paleozoic to Middle Jurassic (300-150 Ma) silicic magmatic rocks that erupted inboard of the Gondwana margin is a possible Phanerozoic analogue to the extensive Middle Proterozoic (1500-1350 Ma) Silicic province that underlies much of the southern mid-continent of North America as mentioned in this paper.
Abstract: A vast region of upper Paleozoic to Middle Jurassic (300-150 Ma) silicic magmatic rocks that erupted inboard of the Gondwana margin is a possible Phanerozoic analogue to the extensive Middle Proterozoic (1500-1350 Ma) silicic magmatic province that underlies much of the southern mid-continent of North America. Like the North American rocks, the Gondwana silicic magmas appear to be melts of crust that formed about 200-300 m.y. earlier. In the North American case, this older crust formed and was accreted to the continent during a major period of crustal formation (1700-1900 Ma), whereas in the Gondwana case, the crust that melted consisted mainly of magmatic are terranes accreted to the continental margin during the Paleozoic. In both cases, basic to intermediate magmatic rocks are extremely rare and magmatism is less abundant in regions that contain older (and previously melted) crust. The similarities between the North American and Gondwana silicic rocks suggest that both suites formed in extensional settings where basaltic magmas, ponded at the base of the preheated crust, caused extensive crustal melting that inhibited upward passage of the basalts. In both cases, silicic volcanism occurred after major assembly of a supercontinent by subduction and accretion processes, and before breakup of the supercontinent. By analogy with the polar wander curves for Gondwana, the granite-rhyolite provinces may have formed during a period of very slow motion of the supercontinents relative to the poles.

354 citations


Journal ArticleDOI
TL;DR: In this article, the authors apply the rifting model describing the formation and further evolution of rift structures in the continental crust leads to the conclusion that the West Congolian belt, as traditionally described, is incomplete and has to be supplemented by the Mayumbian belt and a rift structure situated farther to the west.

345 citations


Journal ArticleDOI
TL;DR: Basalt glasses from the Central Indian Ridge are distinct isotopically from mid-ocean ridge basalts (MORB) of the Indian Ocean triple junction and western few hundred kilometers of the Southeast Indian Ridge.
Abstract: Basalt glasses from the Central Indian Ridge are distinct isotopically from mid-ocean ridge basalts (MORB) of the Indian Ocean triple junction and western few hundred kilometers of the Southeast Indian Ridge. In particular, very low 206Pb/204Pb and high 87Sr/86Sr signatures, which characterize the latter region, are absent over most of the Central Indian Ridge. In turn, lavas from the unusually deep eastern 1100–1500 km of the Southwest Indian Ridge are different chemically and isotopically from those of the above areas. A rather abrupt eastern boundary to Southwest Indian Ridge-type compositions occurs at or very near the geographic triple junction. This provinciality in western Indian Ocean ridge basalts partly mirrors fundamental regional differences in the underlying mantle but, at least between the eastern Southwest Indian Ridge and the western Southeast Indian Ridge and triple junction, also may reflect variations in extent and depth of melting in a vertically zoned upper mantle. A pronounced low eNd, high 206Pb/204Pb, high 87Sr/86Sr anomaly exists on the Central Indian Ridge at the Marie Celeste Fracture Zone and on the adjacent ridge segment to the south. Despite the great distance (>1100 km) of Reunion Island from the ridge, this zone appears to demark a region of mantle containing substantial Reunion hotspotlike material. Several old (35–60 m.y.) Deep Sea Drilling Project basalts which erupted on the ancestral Central Indian Ridge also record a significant Reunion hotspotlike influence, whereas a 46-m.y.-old sample that formed farther from the presumed locus of the hotspot possesses isotopic values identical to many present (non-Marie Celeste area) Central Indian Ridge MORB. The variably expressed and/or heterogeneous low 206Pb/204Pb material partly responsible for the isotopic distinctiveness of Indian Ocean ridge basalts may have entered into the Indian MORB mantle as a result of continental lithospheric remobilization preceding the breakup of Gondwana, particularly from the portion that would eventually become Greater India.

306 citations


Journal ArticleDOI
TL;DR: The stage for the Variscan orogeny in Europe was set by the Cambro-Ordovician break-up of the northern margin of Gondwana into several microcontinental fragments separated by evolved rifts or narrow oceans as discussed by the authors.

194 citations


Journal ArticleDOI
TL;DR: In the Westland-Nelson provinces of New Zealand, high grade metamorphic and granitic basement rocks showing mylonitic ductile deformation are juxtaposed beneath low-grade metasedimentary rocks and undeformed granites by uplift on low-angle detachment faults.
Abstract: In Westland-Nelson provinces of New Zealand, high-grade metamorphic and granitic basement rocks showing mylonitic ductile deformation are juxtaposed beneath low-grade metasedimentary rocks and undeformed granites by uplift on low-angle detachment faults. Several metamorphic core complexes analogous to those described from western North America are recognized. In the Paparoa Range, basement rocks include late Precambrian(?) paragneiss and granitic rocks of both Paleozoic and Cretaceous ages. Cover rocks include Ordovician turbidites, Paleozoic and Cretaceous granites, and mid-Cretaceous breccia-conglomerates. Brittle deformation and hydrothermal alteration (silica, chlorite, hematite, carbonate ± fluorite, uranium) characteristic of the detachment zone are also superimposed on uppermost lower-plate mylonites. Kinematic indicators in the mylonitic rocks including composite S-C febrics indicate that the detachment faults on the northeast and southwest sides of the Paparoa Core Complex had opposite senses of shear, with cover rocks on both sides moving away from the metamorphic core. Ductile deformation postdates several 114±18 Ma granitic plutons but by 108 Ma had ceased to affect at least some of the rocks currently exposed. Mylonitic rocks were uplifted to the surface and eroded into evolving half-grabens by 105–100 Ma. Uplifted basement yields K-Ar dates as young as 88 Ma, and tilting of the graben sediments indicates detachment continued well into the Late Cretaceous, when both cover and basement were intruded by alkali lamprophyre dykes. The Nelson-Westland core complexes occur within an Early Cretaceous granitic province characterized by relatively radiogenic strontium. The boundary of this province, the NW trend to mid-Cretaceous half-grabens, the NNE trend of stretching lineations in mylonitic rocks, and the ESE trend of late Cretaceous lamprophyre dykes indicate that regional extension was maintained in a NNE direction for much of the Cretaceous. This regional extension may be part of an “extension corridor” which traversed the entire Gondwana continental margin from NE Queensland, Australia, to Marie Byrd Land, Antarctica. Extension preceded opening of the Tasman Sea between New Zealand and Australia at approximately 84 Ma and closely followed long-lived compression on the Pacific convergent margin of Gondwana. The presence of core complexes in western New Zealand contrasts with the Australian margin to the Tasman Sea and lends support to simple shear models of continental rifting.

194 citations


01 Jan 1989
TL;DR: A Mesozoic extensional deformation played a key role in basin formation in Argentina as discussed by the authors, and the sedimentary fill associated with extension can generally be divided into two units of supersequence rank--a lower, wedge-shaped succession deposited during active, fault-driven subsidence and an upper, wider-spread unit deposited during thermally driven subsidence after faulting had essentially ceased.
Abstract: Mesozoic extensional deformation played a key role in basin formation in Argentina. Extension persisted from Middle Triassic to Late Cretaceous, although the intensity of deformation and the areas affected varied considerably with time. Initial subsidence began in many Argentine basins, and in almost all of the hydrocarbon-producing basins, during these extensional episodes. The sedimentary fill associated with extension can generally be divided into two units of supersequence rank--a lower, wedge-shaped succession deposited during active, fault-driven subsidence and an upper, wider-spread unit deposited during thermally driven subsidence after faulting had essentially ceased. Examples from the Middle Triassic of the Cuyo basin, Early Jurassic of the Neuquen basin, and Early Cretaceous of the Oran basin document the similarities and differences between basins formed at different times. Even though Mesozoic extension in Argentina covered a long time span (about 150 m.y.), we believe that the various episodes are related. We favor an explanation that links the initiation of extension with subduction-driven processes along the western edge of the South American sector of the Gondwana supercontinent.

146 citations


Journal ArticleDOI
TL;DR: In this article, gravity modelling of the Nigeria and East Niger rift basins shows the extent and nature of the broad (regional) positive Bouguer anomaly associated with these rifts.

122 citations


Journal ArticleDOI
TL;DR: Fossil evidence from Antarctica and closely associated regions in the Creataceous southern Gondwanan assembly confirms that Antarctica was a Cretaceous origination and dispersal region of certain elements of today's southern hemispheric humid and perhumid forests as mentioned in this paper.
Abstract: Although it is well known that certain Gondwanic elements of present-day austral temperate rainforests occurred on Antarctica during latest Cretaceous to early Tertiary times, there has been insufficient factual evidence for pinpointing the cradle of these forests. Fossil evidence from Antarctica and closely associated regions in the Creataceous southern Gondwanan assembly confirms that Antarctica was a Cretaceous origination and dispersal region of certain elements of today's southern hemispheric humid and perhumid forests. Antarctic origins are indicated for the fern Lophosoria, the podocarp gymnosperms Lagarostrobus and Dacrydium, Nothofagus, Ilex, and several lineages of the Proteaceae; migration to their present regions of distribution was probably step-wise. Antarctica also served as a Cretaceous dispersal corridor for other angiosperms represented today in mid to low latitude austral regions. These include Ascarina (or its stock), Myrtaceae, Gunneraceae, and Winteraceae, all of which had earlier histories in northern Gondwana or southern Laurasia. Origination and dispersal appears to be related to changing environmental circumstances associated with fragmentation of Gondwana and opening and enlargement of the southern oceans.

103 citations


Journal Article
TL;DR: OCHEV and SHISHKIN as mentioned in this paper showed that the Triassic land vertebrates comprises three successive global epoches referred to as proterosuchian, kannemeyeroid and dinosaur ones.
Abstract: OCHEV, V. G. and SHISHKIN, M. A.: On the principles of global correlation af the continental Triassic on the tetsapods. Acta Palaeont. Polonica, 34, 2, 143--173, 1989. History of the Triassic land vertebrates comprises three successive global epoches referred to as proterosuchian, kannemeyeroid and dinosaur ones. The earliest and the middle epoches are typified by the regional faunal sequence of East Europe. The proterosuchian time spaas here the Neorhachitome and Parotosuchus faunas, the former being directly correlated with the Induan-Lower Olenekian, and the latter with the Upper Olenekian (Spathian). The Eryosuchus and Mastodonsaurus faunas of the kannemeyeroid epoch in East Europe are Middle Triassic in age and correspond to the Muschelkalk and Lettenkohle respectively. An evidence is brought for contemporaneity of the proterosuchian-kannemeyeroid biotic replacement in Laurasia and Gondwana. This implies the Middle Triassic age of the Cynognathus Zone of South Africa and its equivalents in South America. The bulk of Lystrosausus fauna in Gondwana is suggested to range over the most of, or the whole, Early Triassic. K e y w 0 r d s: Triassic tetrapods, biotic epoches, correlation.

75 citations


Journal ArticleDOI
TL;DR: In this paper, the authors outline the lithological and biotic succession across the late Precambrian to early Cambrian interval for the Dalir and Valiabad successions of the Elburz Mountains of Iran.
Abstract: The lithological and biotic succession across the late Precambrian to early Cambrian interval is outlined for the Dalir and Valiabad successions of the Elburz Mountains of Iran. The Lower Dolomite Member contains an assemblage of phosphatic tubes and other poorly preserved remains. The succeeding Lower Shale Member bears macroscopic chuariamorphid algae. Early skeletal fossil diversity rises through the Middle Dolomite Member, with the successive appearance of Protohertzina anabarica, Cambrotubulus decurvatus and Anabarites trisulcatus, culminating near the top of the dolomites with the appearance of Purella sp., Maikhanella multa, Tiksitheca licis and circothecids. This succession is compared with lower to upper parts of the Nemakit-Daldyn Formation of Siberia. The overlying Upper Shale Member bears phosphatic beds at its base with allathecids and an uncoiled pelagiellid (?Aldanella sp.) that suggest comparison with lower Tommotian strata and the Precambrian–Cambrian boundary phosphorite event of southern and central Asia. A rich assemblage of molluscs appears high in the Upper Shale Member, including the Latouchella korobkovi group and the Pelagiella lorenzi group. The succession is broadly homotaxial with those from the Siberian Platform and Mongolia and those platforms bordering Gondwana (India, Kazakhstan, South China).

Journal ArticleDOI
TL;DR: In this paper, the Williams Point Beds fossil flora is reassigned to the Cretaceous, and there is some evidence for a more restricted Albian-Cenomanian age.
Abstract: A terrestrial sequence on Livingston Island, South Shetland Islands, known as the Williams Point Beds contains a well-preserved, diverse fossil flora previously assigned a Triassic age. Because of their supposed age, volcanic provenance and evidence for active volcanism, the Williams Point Beds have occupied a unique position in Gondwana (pre-Jurassic) stratigraphy in the Antarctic Peninsula region. However, a large new collection of plant specimens obtained at Williams Point has yielded several species of angiosperm leaves, which are abundant and occur at all levels within the Williams Point Beds sequence. Thus, a Triassic age is no longer tenable. On the basis of the plants present and published radiometric ages for associated strata, the Williams Point Beds fossil flora is reassigned to the Cretaceous, and there is some evidence for a more restricted Albian–Cenomanian age. This revision of the age of the Williams Point Beds removes all direct evidence for an active Triassic volcanic arc in the Antarctic Peninsula region.

Journal ArticleDOI
TL;DR: A detailed, palinspastically restored reconstruction of the circum-Central Atlantic continents and incorporation information on the distribution, age and correlation of Precambrian and Paleozoic rocks are presented in this paper.

Journal ArticleDOI
01 May 1989-Geology
TL;DR: Biotic migration patterns provide a history of relative climate change that can be used to study Dinantian and Namurian (Carboniferous) climates High-latitude warming between the middle and late Visean may have been caused by the collision of Laurussia and Gondwana as mentioned in this paper.
Abstract: Biotic migration patterns provide a history of relative climate change that can be used to study Dinantian and Namurian (Carboniferous) climates High-latitude warming between the middle and late Visean may have been caused by the collision of Laurussia and Gondwana High-latitude cooling and equatorial warming between the Namurian A and B may have been caused by the onset of glaciation in the Southern Hemisphere Patterns of faunal migration and extinction and floral radiation were similar during Namurian and Miocene glacial onsets, and provide criteria for assessing other extinction events tied to changes in paleoclimate

Journal ArticleDOI
TL;DR: A plate tectonic model is presented in this paper explaining the evolution of the Variscan belt of Europe, which regards the Iapetus Ocean and its branch, the Tornquist Sea, as the only ocean involved in the Caledonian, Variscans and Alleghenian mega-orogen.

Journal ArticleDOI
TL;DR: Squamastrobus tigrensis nov. gen. has been found in early Cretaceous strata (Baquero Formation), Santa Cruz Province, Argentina as discussed by the authors.

Journal ArticleDOI
TL;DR: In this paper, a lower intercept age of 114 ± 18 m.y.y is defined as the crystallization age of the orthogneiss magmas of the amphibolite facies of the Charleston Metamorphic Group, western South Island, New Zealand.

Journal ArticleDOI
TL;DR: Palynofloral assemblages consisting of forty-four pollen and spore species assignable to thirty-six form genera were recovered from shales and coals of the lower part of the Falla Formation (Upper Triassic) from Mount Falla in the Central Transantarctic Mountains, Antarctica.

Journal ArticleDOI
01 Sep 1989-Geology
TL;DR: The first discovery of abundant Devonian vertebrates from Thailand is reported in this article, where an unusual form of coronodontid shark tooth with six equal-sized cusps is found only in the Upper Devonian of Thailand (Shan-Thai terrane) and south China, and a new species of Phoebodus is reported that occurs elsewhere only in south China and Australia (east Gondwana terrane).
Abstract: We report the first discovery of abundant Devonian vertebrates from Thailand An unusual form of coronodontid shark tooth with six equal-sized cusps occurs only in the Upper Devonian of Thailand (Shan-Thai terrane) and south China, and a new species of Phoebodus is reported that occurs elsewhere only in south China and Australia (east Gondwana terrane) The occurrence of the chondrichthyan Harpagodens ( Thrinacodus ) ferox Turner 1982 in the Late Devonian of Thailand, Australia, and south China predates the appearance of this species in Euramerica (early Carboniferous) These data suggest Late Devonian proximity of the Shan-Thai, south China, and east Gondwana terranes, and is in accord with recent paleomagnetic data

Journal ArticleDOI
TL;DR: The region of the North West Shelf dealt with in this paper is underlain by three of the four basins which make up the Westralian Superbasin this paper.
Abstract: The region of the North West Shelf dealt with in this paper is underlain by three of the four basins which make up the Westralian Superbasin The Bonaparte Basin lies outside the scope of this paper; the other basins are the Browse Basin, the offshore Canning Basin, here named the Western Canning Basin, and the offshore Carnarvon Basin, here called the Northern Carnarvon Basin Sediments belonging to ten depositional sequences (Pz5, Mzl to Mz5, and Czl to Cz4) are present in the basins, the oldest being of Late Carboniferous and Permian age (Pz5) Deposition commenced in rift (interior fracture) basins under fluvial/deltaic conditions in the Late Permian/Early Triassic (Mzl), when the North West Shelf was part of Gondwana Continental breakup took place in the Middle Jurassic (breakup unconformity between Mz2 and Mz3), and marine conditions prevailed over the Westralian Superbasin thereafter, with deposition taking place in a marginal sag setting Siliciclastic sediments gave place to carbonates in the Late Cretaceous (Mz5) as the Indian Ocean grew larger Parts of the area have been under permit since 1946, and to date some 227 exploration wells have been drilled The most intensive exploration has taken place in the Northern Carnarvon Basin (191 wells), followed by the Browse Basin (20 wells), and Western Canning Basin (16 wells) Thirty- four economic and potentially economic discoveries have been made The main target reservoirs are Triassic, Jurassic and Cretaceous, and the regional seals are Triassic and Cretaceous The fields are of two types: pre- breakup unconformity (mainly tilted horst blocks), and post- breakup unconformity (usually four- way dip closures) Of the five producing fields, the North Rankin Gas Field is a pre- breakup field, while the four oil fields (Barrow, Harriet, South Pepper and North Herald) are all post- breakup

Journal ArticleDOI
TL;DR: The early Ordovician was a time of maximum continental separation and hence a critical time when faunal evidence can be used to assess palaeogeography in a critical way as discussed by the authors.
Abstract: The early Ordovician was a time of maximum continental separation and hence a time when faunal evidence can be used to assess palaeogeography in a critical way. We summarize the known trilobite occurrences (18 genera) from the Arenig–Llanvirn of the Lake District, and record some genera for the first time. Maps of the distribution of some of these forms are given. All genera except Cyclopyge were confined to the Gondwana continent at the time, and some are known from many localities; and two species are widespread in England, Wales, France, Iberia and Bohemia. The fauna is entirely distinct from those of Scandinavia and North America. All the palaeontological evidence points to the Lake District being adjacent to Ordovician Gondwana. In the earlier Ordovician it is not reasonable to suggest that the Iapetus Ocean lay to the south of the Lake District as did Allen (1987).

Journal ArticleDOI
TL;DR: A variety of lithostratigraphic units may be outlined within the pre-Mesozoic crystalline basement of the Atlantic and Gulf Coastal Plains of the United States, including a group of metamorphic rocks of variable grade together with deformed and retrogressed granite in southwestern Alabama and southeastern Mississippi as mentioned in this paper.

Journal ArticleDOI
TL;DR: In the late Jurassic, the belemnite genera Hibolithes and Belemnopsis were abundant and widespread in Tethys, characterizing a Tethyan Realm that extended south from southern Europe and Asia to Antarctica and the rest of Gondwana.
Abstract: Abstract In the late Jurassic, the belemnite genera Hibolithes and Belemnopsis were abundant and widespread in Tethys, characterizing a Tethyan Realm that extended south from southern Europe and Asia to Antarctica and the rest of Gondwana. Although a distinct Southern Hemisphere ‘Austral’ belemnite realm counterbalancing the northern Boreal Realm was absent, it is clear that a significant degree of endemicity existed at the species level, with distinct species groups in Indonesia, Madagascar, Australasia, South America and so on. Trans-Gondwanan faunal links first developed in the late Jurassic shelf seaway between Antarctica, Madagascar and India. Belemnopsis became extinct in southern Europe, and was left as a relict, endemic to this trans-Gondwanan seaway. In the Aptian the Belemnopseidae were eventually replaced around Gondwana by the endemic family Dimitobelidae, which developed as the Antarctic—Australasian core of Gondwana began to drift south. In Tethys few genera remained, the Tethyan Realm finally breaking down in the late Cretaceous. Initially the Dimitobelidae were widespread in Gondwanan seas, the trans-Gondwanan links developed in the Jurassic being maintained. However, as Gondwana fragmented further in the late Cretaceous, these links broke down and the Dimitobelidae survived only in the Antarctic-Australasian region which was retreating southwards.

Journal ArticleDOI
TL;DR: In this article, over 400 rock samples from 30 sites were collected for paleomagnetic study from the Brook Street terrane within the Takitimu Mountains in western Southland, New Zealand.
Abstract: Over 400 rock samples from 30 sites were collected for paleomagnetic study from the volcanogenic section in the Brook Street terrane within the Takitimu Mountains in western Southland, New Zealand. The section includes igneous and sedimentary rocks of the Permian Takitimu Group and White Hill Intrusive Suite. Many of the samples show a partial or complete remagnetization in the present field because of a recent acquisition of viscous remanent magnetization. An Early Permian direction (inclination = 46.1°, declination = 257°), isolated from the Heartbreak and Chimney Peaks formations of the Takitimu Group, indicates a low paleolatitude to midpaleolatitude, position (27° ± 5°) for the Brook Street terrane. Directions from the Late Permian (?) White Hill Intrusives (inclination = 64.6°, declination = 173.3°) suggest a slightly higher paleolatitude than the Early Permian Takitimu Group directions and 70°–90° of intervening clockwise rotation. Plate reconstructions and paleomagnetic data predict a high paleolatitude for the New Zealand margin of Gondwana throughout the late Paleozoic and Mesozoic. The low paleolatitude to middle paleolatitude, implied by the Early Permian Brook Street result, together with the oceanic nature of the Brook Street arc, suggest that the Brook Street terrane is allochthonous to the margin of Gondwana. A published Late Triassic/Early Jurassic paleomagnetic pole from the adjacent Murihiku terrane indicates a high paleolatitude. This suggests that the Brook Street and Murihiku terranes are genetically distinct.

Journal ArticleDOI
TL;DR: In this paper, the authors divided the Godavari basin into three parts namely, Chintalapudi, and coastal sub-basins, and interpreted the characteristics of a half-graben.

Journal ArticleDOI
TL;DR: The Irish Caledomde terranes occupied a variety of sites marginal to the cratons of Laurentia, Baltica and Gondwana as mentioned in this paper, and were dominated by Toquima-Table Head faunas in the early Ordovician.
Abstract: The Irish Caledomde terranes occupied a variety of sites marginal to the cratons of Laurentia, Baltica and Gondwana. Palaeontological data provide age constraints on the timing of sedimentary linkage and the age of overlap sequences. The Northwestern terrane is characterized by the development of Toquima–Table Head faunas in the early Ordovician in contrast to the Celtic faunas of the Bellewstown and Rosslare terranes. During the middle Ordovician the Northwestern terrane and the Scottish equivalent of the Central terrane were occupied by the Scoto–Appalachian fauna. The Leinster terrane was dominated by Anglo-Welsh elements with varying proportions of the Scoto-Appalachian and Baltic faunas across the terrane. In the Iapetus suture zone in the east of Ireland the Grangegeeth terrane is characterized by a predominantly Scoto-Appalachian fauna.

Journal ArticleDOI
TL;DR: In this article, the upper Jurassic and lower Cretaceous anoxic mudstones and air-fall ashes of the Nordenskjold Formation are exposed on the eastern coast of Graham Land.
Abstract: Upper Jurassic–Lower Cretaceous anoxic mudstones and air-fall ashes of the Nordenskjold Formation are exposed on the eastern coast of Graham Land. Deformation of the strata has a long history spanning dewatering and lithification and was probably produced in a strike-slip tectonic regime. Available evidence suggests the onset of deformation in the region was during Tithonian times. The strike-slip deformation provides further evidence of a plate boundary along the eastern margin of the peninsula during the break-up of Gondwana and the movement of the crustal blocks of West Antarctica. It may also be related to a change in the spreading history of the Weddell Sea region and be the cause of a major facies change from fine anoxic to coarse clastic sedimentation.

Journal ArticleDOI
TL;DR: In this article, the authors proposed three models to account for the dextral offset observed between lithologic/geochronologic provinces and major fault zones of the two continents, which is consistent with the offset in Proterozoic paleopoles from Venezuela and Liberia.

Journal ArticleDOI
TL;DR: The final continental collision of Gondwana with the Appalachian-Variscan fold belt during mid-Permian times is evident from (1) the simultaneous deformation of the entire fold belt marked by a thin-skin structural style in the Appalachians and in parts of the Variscan front (Midi Fault), (2) the disruption of the Hercynian zones in Western Europe and (3) left-lateral transcurrent displacement visible in features such as the leucogranite belt in France and associated with thrusting of the Ales, Saint-E

Book ChapterDOI
01 Jan 1989
TL;DR: The German deep drilling program of the Federal Republic of Germany (Kontinentales Tiefbohrprogramm der Bundesrepublik Deutschland, KTB) and the closely associated German Continental Seismic Reflection Program (Deutsches Kontinentale Reflexionsseismisches Programm, DEKORP) are major German contributions to the understanding of the Central European crust.
Abstract: The Continental Deep Drilling Program of the Federal Republic of Germany (Kontinentales Tiefbohrprogramm der Bundesrepublik Deutschland, KTB) and the closely associated German Continental Seismic Reflection Program (Deutsches Kontinentales Reflexionsseismisches Programm, DEKORP) are major German contributions to the understanding of the Central European crust. This crustal region is distinguished by its position between three Precambrian continental blocks of Pangea, namely Eurasia, North America-Green- land and Africa, and despite its relatively young age of about 500 Ma has a rather complex history. Formation of the Central European crust started in the early Paleozoic during an important rifting episode in Cambro-Ordovician time which resulted in the break-up of Gondwana, development of Variscan microplates and opening of at least some of the Variscan basins. Rifting dismembered an old continental crust previously generated in the course of several Precambrian orogenies. In the subsequent collision between Gondwana and Laurentia/Baltica the Variscan belt of Europe was formed by welding together the Variscan microplates and by incorporation of proto-oceanic basins, shelf areas, accretionary wedges, island arcs and back-arc troughs through compressive, subduction-related processes.