Search results for "WAN"
showing 10 items of 854 documents
NO EXCESSIVE CRUSTAL GROWTH IN THE CENTRAL ASIAN OROGENIC BELT: FURTHER EVIDENCE FROM FIELD RELATIONSHIPS AND ISOTOPIC DATA
2017
Abstract We provide new field observations and isotopic data for key areas of the Central Asian Orogenic Belt (CAOB), reiterating our previous assessment that no excessive crustal growth occurred during its ca. 800 Ma long orogenic evolution. Many Precambrian blocks (microcontinents) identified in the belt are exotic and are most likely derived from the northern margin of Gondwana, including the Tarim craton. Ocean opening in the Palaeo-Asian Ocean, arc formation and accretionary processes began in the latest Mesoproterozoic along the southern margin of the Siberian craton and continued into the Neoproterozoic, giving rise to tectono-metamorphic terranes distinct from the exotic microcontin…
Reply to J. Berger's comment on the article “Discovery of metamorphic microdiamonds from the parautochthonous units of the Variscan French Massif” by…
2015
International audience
How to make a transverse triple junction—New evidence for the assemblage of Gondwana along the Kaoko-Damara belts, Namibia
2016
T-shaped orogenic triple junctions between mobile belts usually form in two unrelated stages by subsequent and oblique continental collisions separated by a significant time span. Besides these “oblique triple junctions”, another type, named “transverse triple junctions”, may exist. Such junctions are created by a more complex mechanism of partly contemporaneous convergence of three cratons in a restricted time frame, involving strike slip. The Neoproterozoic–Cambrian Kaoko-Damara junction between the Rio de la Plata, Congo, and Kalahari cratons in Namibia is an example of such a transverse orogenic triple junction, formed by at least four subsequent but partly related deformation events. I…
A Damara orogen perspective on the assembly of southwestern Gondwana
2008
The Pan-African Damara orogenic system records Gondwana amalgamation involving serial suturing of the Congo-Sao Francisco and Ro ´o de la Plata cratons (North Gondwana) from 580 to 550 Ma, before amalgamation with the Kalahari - Antarctic cratons (South Gondwana) as part of the 530 Ma Kuunga-Damara orogeny. Closure of the Adamastor Ocean was diachronous from the Aracuao ´ Belt southwards, with peak sinistral transpressional deformation followed by craton overthrusting and foreland basin development at 580- 550 Ma in the Kaoko Belt and at 545-530 Ma in the Gariep Belt. Peak deformation/metamorphism in the Damara Belt was at 530-500 Ma, with thrusting onto the Kalahari Craton from 495 Ma thro…
Serbo-Macedonian revisited: A Silurian basement terrane from northern Gondwana in the Internal Hellenides, Greece
2009
Abstract New geochronological and geochemical data on basement orthogneisses from the Vertiskos Unit of the Serbo-Macedonian Massif (SMM), Internal Hellenides, northern Greece, are used in order to constrain the pre-Alpine tectonic history of the basement units in the metamorphic hinterland of the Hellenides. The prevailing rock types in the Vertiskos crystalline basement are coarse-grained biotite augengneisses with subordinate leucocratic muscovite gneisses and two-mica gneisses. Zircon Pb–Pb and U–Pb ages on 20 samples range from 425.9 ± 4.2 Ma to 443.4 ± 5.5 Ma with a mean of 432.2 ± 3.2 Ma and are interpreted as primary crystallisation ages of the basement granites on the basis of the …
Elements of the Archean thermal history and apparent polar wander of the eastern Kaapvaal Craton, Swaziland, from single grain dating and paleomagnet…
1989
Abstract Single grains of zircon, hornblende, biotite and feldspar have been dated to define the thermal history of the Archean Mbabane Pluton, Swaziland. Coincident207Pb/206Pb zircon and40Ar/39Ar hornblende ages suggest that the pluton underwent rapid cooling to about 450°C at the time of emplacement at ∼ 2690 Ma. Because the Mbabane Pluton is one of a suite of granites which represent the last major Archean intrusive event in the eastern Kaapvaal Craton, this time of emplacement marks the end of cratonization. Much younger biotite and feldspar ages indicate argon loss, perhaps due to several low-temperature events related to dike intrusion at 2000–2300 Ma. From such a thermal history, the…
U-Pb and Pb-Pb zircon ages for metamorphic rocks in the Kaoko Belt of Northwestern Namibia: A Palaeo- to Mesoproterozoic basement reworked during the…
2004
The Kaoko Belt belongs to the Neoproterozoic mobile belt system of western Gondwana, whose geodynamic evolution is assumed to have resulted from collision between the Congo Craton (present Africa) and the Rio de la Plata Craton (present South America). Several magmatic intrusion periods can be distinguished in the coastal area of this belt, based on conventional U-Pb, SHRIMP and Pb-Pb evaporation analyses on zircons. The prevailing igneous rock types are of granitic to tonalitic composition. A Palaeoproterozoic terrain with U-Pb magmatic emplacement ages between ~2.03 and 1.96 Ga may be correlated with the Eburnian event (~1.8 to 2.0 Ga), which is widespread in Africa. Additionally, two dis…
Taxonomy and evolution of the Triassic conodont Pseudofurnishius
2013
Pseudofurnishius is a late Anisian (Pelsonian)—early Carnian (Cordevolian) conodont genus of gondolellid stock, characteristic for the Sephardic Province and restricted to the “Southern Tethys” region of the northern margin of Gondwana. Its most commonly found species, Pseudofurnishius murcianus, appears at the base of the Ladinian (Fassanian). The Ladinian material of Spain reveals its ontogeny characterised by initial lateral protrusions from the carina that may develop first mono-platform and later bi-platform units, finally evolving into elaborated multi-denticulated forms. The late Anisian—early Carnian phylogenesis of Pseudofurnishius priscus → P. shagami → P. murcianus is proposed. A…
Ar LoRaWAN raidītājiem aprīkotu objektu monitoringa sistēma
2022
Putnu migrācijas pētījumi palīdz uzzināt daudz jauna par putnu dzīvesveidu. Šiem pētījumiem bieži tiek izmantoti nelieli putni, jo tie ir vieglāk pieejami. Nelielu putnu migrācijas pētījumos šobrīd īsti nav iespēju noteikt putnu lokāciju migrācijas laikā. Izmantojot šā brīža modernākās ierīces, putnu migrācijā dati tiek iegūti, uzliekot vides uztveršanas ierīci putnam, noņemot to nākamajā ligzdošanas periodā (pēc gada). Migrācijas ceļi pēc šādas metodes tiek rēķināti no sensoru datiem pēc tam, kad putns ir atgriezies ligzdošanas vietā. Tā kā putna ķermenis ir viegls, tad arī ierīcei, kas lokācijas datus pārraidītu, ir jābūt nelielai, vieglai un ar zemu enerģijas patēriņu. Darbā apskatītais …
Wpływ zasady cross compliance na kształtowanie nowej ekonomiki rolnictwa na przykładzie badań w regionie opolskim
2009
Na nową organizację rolnictwa w przestrzeni europejskiej szczególny wpływ mają zasady zreformowanej WPR: decoupling, cross compliance, modulacja, dyscyplina budżetowa. Centralne miejsce wśród tych zasad odgrywa zasada współzależności, która reguluje wewnętrzną organizację rolnictwa, pozostałe zasady dotyczą w większym stopniu jego relacji z otoczeniem (rynkowym, składowymi przestrzeni wiejskiej). Prezentowane w pracy wyniki badań przeprowadzonych w towarowych gospodarstwach rolnych regionu opolskiego potwierdzają wpływ zasady współzależności na decyzje produkcyjne rolników, które w coraz większym zakresie wynikają z wiedzy o zintegrowanych i precyzyjnych metodach zarządzania warsztatem prod…