Showing papers on "Gondwana published in 2012"
TL;DR: A significant number of new palaeomagnetic poles have become available since the last time a compilation was made (assembled in 2005, published in 2008) to indicate to us that a new and significantly expanded set of tables with palaeOMagnetic results would be valuable, with results coming from the Gondwana cratonic elements, Laurentia, Baltica/Europe, and Siberia as mentioned in this paper.
1,094 citations
TL;DR: A review of the current understanding of the many inherent tectonic problems of the Altaids can be found in this paper, which is timely and appropriate to present a review of current understanding.
633 citations
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TL;DR: The Cambrian Period was characterized by the appearance of metazoans with mineralized skeletons, explosion in biotic diversity and disparity, infaunalization of the substrate, occurrence of metazoan Konservat Fossil-lagerstatten, establishment of most invertebrate phyla, strong faunal provincialism, dominance of trilobites, generally warm climate but with possible glacial-interglacial cycles in the later part, opening of the Iapetus Ocean, progressive equatorial drift and separation of Laurentia, Baltica, Siberia,
Abstract: Appearance of metazoans with mineralized skeletons, “explosion” in biotic diversity and disparity, infaunalization of the substrate, occurrence of metazoan Konservat Fossil-lagerstatten, establishment of most invertebrate phyla, strong faunal provincialism, dominance of trilobites, generally warm climate but with possible glacial–interglacial cycles in the later part, opening of the Iapetus Ocean, progressive equatorial drift and separation of Laurentia, Baltica, Siberia, and Avalonia from Gondwana characterize the Cambrian Period.
353 citations
TL;DR: In this article, three key intervals are evaluated using the concept of the equilibrium-line altitude (ELA) as a control on glaciation to provide insight into two intervals of paradoxical ice distribution during and following glaciation.
267 citations
TL;DR: It is shown that phylogenetic relationships in the gymnosperm family Cupressaceae (162 species, 32 genera) exhibit patterns expected from the Jurassic/Cretaceous breakup of Pangea, and originated during the Triassic.
Abstract: Most extant genus-level radiations in gymnosperms are of Oligocene age or younger, reflecting widespread extinction during climate cooling at the Oligocene/Miocene boundary [∼23 million years ago (Ma)]. Recent biogeographic studies have revealed many instances of long-distance dispersal in gymnosperms as well as in angiosperms. Acting together, extinction and long-distance dispersal are likely to erase historical biogeographic signals. Notwithstanding this problem, we show that phylogenetic relationships in the gymnosperm family Cupressaceae (162 species, 32 genera) exhibit patterns expected from the Jurassic/Cretaceous breakup of Pangea. A phylogeny was generated for 122 representatives covering all genera, using up to 10,000 nucleotides of plastid, mitochondrial, and nuclear sequence per species. Relying on 16 fossil calibration points and three molecular dating methods, we show that Cupressaceae originated during the Triassic, when Pangea was intact. Vicariance between the two subfamilies, the Laurasian Cupressoideae and the Gondwanan Callitroideae, occurred around 153 Ma (124-183 Ma), when Gondwana and Laurasia were separating. Three further intercontinental disjunctions involving the Northern and Southern Hemisphere are coincidental with or immediately followed the breakup of Pangea.
233 citations
TL;DR: The Rheic Ocean was one of the most important oceans of the Paleozoic Era as mentioned in this paper and closed to produce the Ouachita-Alleghanian-Variscan orogen during the assembly of Pangea.
Abstract: The Rheic Ocean was one of the most important oceans of the Paleozoic Era. It lay between Laurentia and Gondwana from the Early Ordovician and closed to produce the vast Ouachita-Alleghanian-Variscan orogen during the assembly of Pangea. Rifting began in the Cambrian as a continuation of Neoproterozoic orogenic activity and the ocean opened in the Early Ordovician with the separation of several Neoproterozoic arc terranes from the continental margin of northern Gondwana along the line of a former suture. The rapid rate of ocean opening suggests it was driven by slab pull in the outboard Iapetus Ocean. The ocean reached its greatest width with the closure of Iapetus and the accretion of the peri-Gondwanan arc terranes to Laurentia in the Silurian. Ocean closure began in the Devonian and continued through the Mississippian as Gondwana sutured to Laurussia to form Pangea. The ocean consequently plays a dominant role in the Appalachian-Ouachita orogeny of North America, in the basement geology of southern Europe, and in the Paleozoic sedimentary, structural and tectonothermal record from Middle America to the Middle East. Its closure brought the Paleozoic Era to an end.
220 citations
TL;DR: The Sao Francisco craton in eastern Brazil hosts sedimentary sequences deposited between the Paleoarchean and Late Neoproterozoic (∼580 ǫ) as discussed by the authors, which besides episodes of global significance record major basin-forming events.
209 citations
TL;DR: In this article, a long-lived Tethys (Rheic, Palaeotethyan and Neotythyan oceans) was reconstructed for the easternmost Mediterranean and adjacent region.
Abstract: Valid palaeotectonic and palaeogeographical reconstructions of the easternmost Mediterranean and adjacent region involve a long-lived Tethys (Rheic, Palaeotethyan and Neotethyan oceans), northward subduction beneath Eurasia and rifting of continental fragments from Gondwana. Rifted microcontinents bordering Gondwana were separated (from south to north) by the Southern Neotethyan ocean, the Berit ocean (new name), the Inner Tauride ocean and the Izmir–Arkara–Erzincan ocean. Mid-Permian to Mid-Triassic pulsed rifting culminated in Late Triassic–Early Jurassic spreading of the Southern Neotethyan oceans (the main focus here). After Early–Mid-Jurassic passive subsidence, the Late Jurassic–Early Cretaceous was characterized by localized alkaline, within-plate magmatism related to plume activity or renewed rifting. Late Cretaceous ophiolites formed above subduction zones in several oceanic basins. Ophiolites were emplaced southwards onto the Tauride and Arabian platforms during the latest Cretaceous. The Southern Neotethys sutured with the Arabian margin during the Early–Middle Miocene, while oceanic crust remained in the Eastern Mediterranean further west. The leading edge of the North African continental margin, the Eratosthenes Seamount, collided with a subduction trench south of Cyprus during the Late Pliocene–Pleistocene, triggering rapid uplift. Coeval Plio-Quaternary uplift of the Taurides may relate to break-off or delamination of a remnant oceanic slab.
174 citations
TL;DR: In this article, the ages and paleogeographic affinities of basement rocks of Tibetan terranes are poorly known, and the Amdo basement is exposed within the Bangong suture zone between the Lhasa and Qiangtang terrans.
171 citations
TL;DR: In this article, secondary ion mass spectrometry (SIMS) was used to estimate the ages of zircons in plagiogranites and gabbros from a suprasubduction zone ophiolitic complex at Manamedu, located along the southern periphery of the Palghat-Cauvery Suture Zone.
152 citations
TL;DR: In this article, the Kibara Belt has been defined as the part of a NW oriented Palaeoproterozoic basement high of the Ubende-Rusizi Belts.
TL;DR: A new biogeographical model for late Mesozoic terrestrial ecosystems is proposed in which Europe and "Gondwanan" territories possessed a common Eurogondwanans fauna during the earliest Cretaceous, and tree reconciliation analyses (TRAs) were performed based onBiogeographical signals provided by a supertree of late Meszoic archosaurs.
Abstract: Late Mesozoic palaeobiogeography has been characterized by a distinction between the northern territories of Laurasia and the southern landmasses of Gondwana. The repeated discovery of Gondwanan lineages in Laurasia has led to the proposal of alternative scenarios to explain these anomalous occurrences. A new biogeographical model for late Mesozoic terrestrial ecosystems is here proposed in which Europe and "Gondwanan" territories possessed a common Eurogondwanan fauna during the earliest Cretaceous. Subsequently, following the Hauterivian, the European territories severed from Africa and then connected to Asiamerica resulting in a faunal interchange. This model explains the presence of Gondwanan taxa in Laurasia and the absence of Laurasian forms in the southern territories during the Cretaceous. In order to test this new palaeobiogeographical model, tree reconciliation analyses (TRAs) were performed based on biogeographical signals provided by a supertree of late Mesozoic archosaurs. The TRAs found significant evidence for the presence of an earliest Cretaceous Eurogondwanan fauna followed by a relatively short-term Gondwana-Laurasia dichotomy. The analysis recovered evidence for a biogeographical reconnection of the European territories with Africa and South America- Antarctica during the Campanian to Maastrichtian time-slice. This biogeographical scenario appears to continue through the early Tertiary and sheds light on the trans-Atlantic disjunct distributions of several extant plant and animal groups. (Archosauria; Atlantogea; Cretaceous; Eurogondwana; palaeobiogeography; Tertiary.)
TL;DR: In this article, the authors examine the influence of data-quality, refined continental fits, and theoretical inclination shallowing corrections, and confirm that the paleomagnetic data can be reconciled with Pangea, without invoking alternative reconstructions or non-dipole fields.
TL;DR: In this paper, detrital zircon age spectra were employed to probe the Precambrian history of the region and to evaluate the link with the Proterozoic supercontinents.
TL;DR: It is now generally accepted that the core of Southeast (SE) Asia was assembled from continental blocks that separated from Gondwana in the Paleozoic and amalgamated with Asian blocks in the Triassic as mentioned in this paper.
Abstract: It is now generally accepted that the core of Southeast (SE) Asia was assembled from continental blocks that separated from Gondwana in the Paleozoic and amalgamated with Asian blocks in the Triassic. Fragments of these Gondwana/Cathaysia blocks rifted and separated from Asia and later re-amalgamated with the SE Asian continental core. Mesozoic rifting of fragments from the Australian margins followed by Cretaceous collisions, and Cenozoic collision of Australia with the SE Asian margin added more continental crust. There can be no doubt that there is Australian crust in SE Asia, including Indonesia, but where this crust came from, and when it arrived, continues to promote discussion. Argoland has been variously identified in Tibet, West Burma, and Borneo. Other fragments supposed to have rifted from Australia are claimed to be in Sumatra, Java, Sulawesi and Sumba. The Banda region is the site of even more controversy because pieces of Australian crust are found in Sulawesi, the North Moluccas, the Banda ...
TL;DR: In this paper, the authors provide estimates for the width, timing, and rates of opening and closing of the Iapetus and Rheic oceans, the evolution of which profoundly infenced Paleozoic global paleogeography.
Abstract: We provide estimates for the width, timing, and rates of opening and closing of the Iapetus and Rheic oceans, the evolution of which profoundly infl uenced Paleozoic global paleogeography. These estimates are primarily derived from the transfer of Ganderia and Avalonia from Gondwana to Laurentia, which led to closure of the Iapetus Ocean and opening of the Rheic Ocean. Ganderia, a long-lived arc terrane, separated from the paleo-Caribbean margin of Amazonia at 505 Ma with a latitudinal speed of ~9 cm/a northward, initiating the Rheic Ocean as a backarc basin. Ganderia’s trailing edge was reduced to ~5 cm/a following opening of a 600‐800-km-wide backarc basin within Ganderia at 475 Ma. Opening and closing of the Iapetus Ocean was largely driven by far-fi eld stresses, slab pull in some places and slab rollback in others.
TL;DR: A new abelisaurid from the Middle Jurassic of Patagonia is reported, Eoabelisaurus mefi gen. et sp.
Abstract: Abelisaurids are a clade of large, bizarre predatory dinosaurs, most notable for their high, short skulls and extremely reduced forelimbs. They were common in Gondwana during the Cretaceous, but exceedingly rare in the Northern Hemisphere. The oldest definitive abelisaurids so far come from the late Early Cretaceous of South America and Africa, and the early evolutionary history of the clade is still poorly known. Here, we report a new abelisaurid from the Middle Jurassic of Patagonia, Eoabelisaurus mefi gen. et sp. nov., which predates the so far oldest known secure member of this lineage by more than 40 Myr. The almost complete skeleton reveals the earliest evolutionary stages of the distinctive features of abelisaurids, such as the modification of the forelimb, which started with a reduction of the distal elements. The find underlines the explosive radiation of theropod dinosaurs in the Middle Jurassic and indicates an unexpected diversity of ceratosaurs at that time. The apparent endemism of abelisauroids to southern Gondwana during Pangean times might be due to the presence of a large, central Gondwanan desert. This indicates that, apart from continent-scale geography, aspects such as regional geography and climate are important to reconstruct the biogeographical history of Mesozoic vertebrates.
TL;DR: In this paper, the authors presented results of systematic and densely spaced aeromagnetic measurements, which have been conducted in 2009/2010 across the Astrid Ridge (Antarctica) and in the western Riiser-Larsen Sea to provide constraints for the early seafloor spreading history between both continents.
TL;DR: In this paper, U/Pb detrital zircon data for the Abt Formation, the principle basin sediments of the Ad Dawadimi Terrane, along with 40 Ar/39 Ar ages on muscovite and whole rock Sm/Nd data were presented.
TL;DR: In this article, new zircon U-Pb age data and geochemistry for the Sa9al metamorphic complex (SMC) in Sinai (Egypt) provide the first robust evidence of latest Mesoproterozoic island arc rocks at the northernmost Arabian-Nubian Shield, possibly indicating that formation of the shield commenced prior to 870 Ma.
Abstract: New zircon U-Pb age data and geochemistry for the Sa9al metamorphic complex (SMC) in Sinai (Egypt) provide the first robust evidence of latest Mesoproterozoic island arc rocks at the northernmost Arabian-Nubian Shield, possibly indicating that formation of the shield commenced prior to 870 Ma. An older series of calc-alkaline volcanic and intrusive rocks yielded ages of ca. 1.03–1.02 Ga. Zircon xenocrysts within these rocks attest to arc magmatism predating the SMC by ∼80 m.y., as well as the minor contribution of Paleoproterozoic crust. Detrital zircons of the SMC pelites exhibit textural and U-Pb age patterns supporting their derivation from the volcanic rocks as arc detritus. A ca. 820 Ma gneissic pluton intruding the SMC indicates that by Cryogenian time, the SMC was already incorporated within the evolving Arabian-Nubian Shield. The 1.0–1.1 Ga SMC rocks provide a possible connection between latest Mesoproterozoic ocean closure during the assembly of Rodinia and the later buildup of Gondwana. There is growing indication, including the findings of this study, that 1.0–1.1 Ga crust composed a more significant component in northernmost Gondwana than hitherto recognized.
TL;DR: The formation of Gondwana took place across a series of Brasiliano-Pan African suture zones that record late Neoproterozoic to earliest Paleozoic collisions between Precambrian cratons as discussed by the authors.
TL;DR: The Estremoz Anticline in the Ossa-Morena Zone (SW Iberia) includes upper Ediacaran detrital rocks unconformably overlain by lower Cambrian carbonate and carbonate rocks as discussed by the authors.
TL;DR: In this article, the authors used the geology and tectonics of a critical part of the Tethyan orogen, represented by Greece and Albania, to shed light on the tectonic development of Tethys on a regional to global scale.
Abstract: The objective of this article is to use the geology and tectonics of a critical part of the Tethyan orogen, represented by Greece and Albania, to shed light on the tectonic development of Tethys on a regional to global scale. A review of existing Tethyan reconstructions reveals little consensus concerning key aspects, such as the timing and direction of subduction, arc magmatism, ophiolite genesis, and continental collision. The regional to local-scale geology of individual regions, therefore, has to be considered in detail to test existing models and to develop a viable tectonic reconstruction. For Carboniferous time, much evidence suggests that the Korabi–Pelagonian crustal unit as exposed in Albania and Greece formed above a northward-dipping subduction zone along the Eurasian continental margin, with Palaeotethys to the south. However, there is also evidence of southward subduction beneath Gondwana, especially from southern Greece and central-southern Turkey. Palaeotethys is inferred to have closed in...
TL;DR: The eastern edge of the Appalachian orogen is composed of a collection of Neoproterozoic-early Paleozoic domains, which are exotic to North America as discussed by the authors.
Abstract: The eastern edge of the Appalachian orogen is composed of a collection of Neoproterozoic – early Paleozoic domains, Avalonia, Carolinia, Ganderia, Meguma, and Suwannee, which are exotic to North America. Differences in the geological histories of these peri-Gondwanan domains indicate that each separated independently from Gondwana, opening the Rheic Ocean in their wake. Cambrian departure of Ganderia and Carolina was followed by the Ordovician separation of Avalonia and Silurian separation of Meguma. After separation in the early Paleozoic, these domains constituted the borderline between the expanding Rheic Ocean and contracting Iapetus Ocean. They were transferred to Laurentia by early Silurian closure of Iapetus and Devonian–Carboniferous closure of the Rheic Ocean during the assembly of Gondwana and Laurentia into Pangaea. The first domain to arrive at Laurentia was Carolinia, which accreted in the Middle Ordovician during the Cherokee orogeny. Salinic accretion of Ganderia occurred shortly thereafter and was followed by the Acadian accretion of Avalonia. The Acadian orogeny was immediately followed by Middle Devonian – Early Carboniferous accretion of Meguma and possibly Suwannee which led to the Fammenian orogeny. The episodicity of orogeny suggests that the present location of these domains parallels their order of accretion. However, each of these crustal blocks was translated along strike by large-scale Late Devonian – Carboniferous dextral strike–slip motion. The breakup of Pangaea occurred outboard of the Paleozoic collision zones that accreted Carolinia, Ganderia, Avalonia, Meguma, and Suwannee to Laurentia, leaving these terranes appended to North America during the Mesozoic opening of the Atlantic.
TL;DR: U-Pb geochronology of detrital zircon from Late Ediacaran (Beiras Group greywackes) and Early Ordovician (Sarnelhas arkosic quartzites and Armorican quartzites of Penacova) sedimentary rocks of the southwest Central Iberian Zone (SW CIZ) constrain the evolution of northern Gondwana activepassive margin transition as discussed by the authors.
TL;DR: The authors reconstructs the evolution of the passive northern margin of peninsular India facing the Neotethys, from the earliest rifting stages in the Carboniferous to final collision with the active southern margin of Asia in the Early Eocene.
TL;DR: In this article, the authors provide an up-to-date and comprehensive review of the early Palaeozoic evolution of the Brabant Massif belonging to the Anglo-Brabant Deformation Belt.
TL;DR: The Rio Negro Complex (RNC) as discussed by the authors consists of a plutonic portion of a magmatic arc built by the E-vergent subduction of the ESE border of the Sao Francisco paleoplate during the amalgamation of Western Gondwana.
TL;DR: Ion probe dating is used to determine the relative ages of amphibolite-facies meta-clastic sedimentary rocks and crosscutting granitoid rocks within an important 'basement' outcrop in northwestern Turkey.
Abstract: Ion probe dating is used to determine the relative ages of amphibolite-facies meta-clastic sedimentary rocks and crosscutting granitoid rocks within an important 'basement' outcrop in northwestern Turkey. U-Pb ages of 89 detrital zircon grains separated from sillimanite-garnet micas chist from the Central Sakarya basement terrane range from 551 Ma (Ediacaran) to 2738 Ma (Neoarchean). Eighty fi ve percent of the ages are 90-110% concordant. Zircon populations cluster at ~550-750 Ma (28 grains), ~950-1050 Ma (27 grains) and ~2000 Ma (5 grains), with smaller groupings at ~800 Ma and ~1850 Ma. Th e fi rst, prominent, population (late Neoproterozoic) refl ects derivation from a source area related to a Cadomian-Avalonian magmatic arc, or the East African orogen. An alternative Baltica-related origin is unlikely because Baltica was magmatically inactive during much of this period. Th e early Neoproterozoic ages (0.9-1.0 Ga) deviate signifi cantly from the known age spectra of Cadomian terranes and are instead consistent with derivation from northeast Africa. Th e detrital zircon age spectrum of the Sakarya basement is similar to that of Cambrian-Ordovician sandstones along the northern periphery of the Arabian-Nubian Shield (Elat sandstones). A sample of crosscutting pink alkali feldspar-rich granitoid yielded an age of 324.3±1.5 Ma, whilst a grey, well-foliated biotite granitoid was dated at 327.2±1.9 Ma. A granitoid body with biotite and amphibole yielded an age of 319.5±1.1 Ma. Th e granitoid magmatism could thus have persisted for ~8 Ma during late Early Carboniferous time, possibly related to subduction or collision of a Central Sakarya terrane with the Eurasian margin. Th e Central Sakarya terrane is likely to have rift ed during the Early Palaeozoic; i.e. relatively early compared to other Eastern Mediterranean, inferred 'Minoan terranes' and then accreted to the Eurasian margin, probably during Late Palaeozoic time. Th e diff erences in detrital zircon populations suggest that the Central Sakarya terrane was not part of the source area of Lower Carboniferous clastic sediments of the now-adjacent Istanbul terrane, consistent with these two tectonic units being far apart during Late Palaeozoic-Early Mesozoic time.
TL;DR: In this article, the southwestern Gondwana basement block configuration in the central Argentinean offshore area was analyzed using gravimetric, magnetic and seismic data and existing onshore tectonic models.