Home About us Contact
|
Home About us Contact | ||
|
|
||
Tertiary
Kinds of Tertiary Terms modified by Tertiary Selected AbstractsPhylogenetics, biogeography and classification of, and character evolution in, gamebirds (Aves: Galliformes): effects of character exclusion, data partitioning and missing dataCLADISTICS, Issue 6 2006Timothy M. Crowe The phylogenetic relationships, biogeography and classification of, and morpho-behavioral (M/B) evolution in, gamebirds (Aves: Galliformes) are investigated. In-group taxa (rooted on representatives of the Anseriformes) include 158 species representing all suprageneric galliform taxa and 65 genera. The characters include 102 M/B attributes and 4452 nucleic acid base pairs from mitochondrial cytochrome b (CYT B), NADH dehydrogenase subunit 2 (ND2), 12S ribosomal DNA (12S) and control region (CR), and nuclear ovomucoid intron G (OVO-G). Analysis of the combined character data set yielded a single, completely resolved cladogram that had the highest levels of jackknife support, which suggests a need for a revised classification for the phasianine galliforms. Adding 102 M/B characters to the combined CYT B and ND2 partitions (2184 characters) decisively overturns the topology suggested by analysis of the two mtDNA partitions alone, refuting the view that M/B characters should be excluded from phylogenetic analyses because of their relatively small number and putative character state ambiguity. Exclusion of the OVO-G partition (with >,70% missing data) from the combined data set had no effect on cladistic structure, but slightly lowered jackknife support at several nodes. Exclusion of third positions of codons in an analysis of a CYT B + ND2 partition resulted in a massive loss of resolution and support, and even failed to recover the monophyly of the Galliformes with jackknife support. A combined analysis of putatively less informative, "non-coding" characters (CYT B/ND2 third position sites + CR +12S + OVO-G sequences) yielded a highly resolved consensus cladogram congruent with the combined-evidence cladogram. Traditionally recognized suprageneric galliform taxa emerging in the combined cladogram are: the families Megapodiidae (megapodes), Cracidae (cracids), Numididae (guineafowls), Odontophoridae (New World quails) and Phasianidae (pheasants, pavonines, partridges, quails, francolins, spurfowls and grouse) and the subfamilies Cracinae (curassows, chachalacas and the horned guan), Penelopinae (remaining guans), Pavoninae sensu lato (peafowls, peacock pheasants and argus pheasants), Tetraoninae (grouse) and Phasianinae (pheasants minus Gallus). The monophyly of some traditional groupings (e.g., the perdicinae: partridges/quails/francolins) is rejected decisively, contrasted by the emergence of other unexpected groupings. The most remarkable phylogenetic results are the placement of endemic African galliforms as sisters to geographically far-distant taxa in Asia and the Americas. Biogeographically, the combined-data cladogram supports the hypothesis that basal lineages of galliforms diverged prior to the Cretaceous/Tertiary (K-T) Event and that the subsequent cladogenesis was influenced by the break-up of Gondwana. The evolution of gamebirds in Africa, Asia and the Americas has a far more complicated historical biogeography than suggested to date. With regard to character evolution: spurs appear to have evolved at least twice within the Galliformes; a relatively large number of tail feathers (, 14) at least three times; polygyny at least twice; and sexual dimorphism many times. © The Willi Hennig Society 2006. [source] DEPOSITIONAL HISTORY AND SEQUENCE STRATIGRAPHY OF OUTCROPPING TERTIARY CARBONATES IN THE JAHRUM AND ASMARI FORMATIONS, SHIRAZ AREA (SW IRAN)JOURNAL OF PETROLEUM GEOLOGY, Issue 2 2004M. Nadjafi The Oligo-Miocene Asmari Formation is one of the most important petroleum reservoir units in the Zagros Basin of south and SW Iran. It mainly consists of limestones and dolomitic limestones with interbedded shales, together with a few intervals of sandstone and gypsum assigned to the Ahwaz and Kalhur Members, respectively. The Asmari Formation rests on the thin-bedded limestones of the Jahrum Formation (Paleocene-Eocene). In this paper, we report on the lithofacies characteristics of these two formations using data from three measured outcrop sections near Shiraz in SW Iran. From field and petrographic data, we have identified four major lithofacies and twelve subfacies which are interpreted to have been deposited in open-marine, shoal, lagoon and tidal flat settings. We show that the Asmari and Jahrum Formations constitute two separate depositional sequences which are separated by a thin palaeosol, representing a type-one sequence boundary which can be correlated with global curves of relative sea-level. Each depositional sequence is composed of many metre-scale shallowing-upward parasequences. This is the first time that the Asmari and Jahrum Formations have been differentiated in the study area. We hope that this study will lead to a better understanding of the Asmari Formation in the subsurface in other parts of the Zagros Basin. [source] Geochronological evidence for pervasive Miocene weathering, Minas Gerais, BrazilEARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2004Isabela de O. Carmo Abstract 40Ar/39Ar laser incremental-heating analyses of 22 individual grains of supergene cryptomelane from three weathering pro,les, up to 400 km apart, in the Rio Doce valley and Barbacena regions at Minas Gerais, Brazil, show that the formation of weathering pro,les in these regions is contemporaneous, suggesting a strong weathering event in the Middle to Late Miocene (10,8 Ma). The preservation of these Miocene samples at or near the present surface suggests that either erosion rates have been very low in the region since the Miocene or that a much thicker weathering mantle was present in the region originally. Assuming a constant thickness of weathering pro,les in the region throughout the Tertiary, we may calculate weathering front propagation rates of 4,8 m Myr,1 during the past 10 Ma. Copyright © 2004 John Wiley & Sons, Ltd. [source] Fire and the Miocene expansion of C4 grasslandsECOLOGY LETTERS, Issue 7 2005Jon E. Keeley Abstract C4 photosynthesis had a mid-Tertiary origin that was tied to declining atmospheric CO2, but C4 -dominated grasslands did not appear until late Tertiary. According to the ,CO2 -threshold' model, these C4 grasslands owe their origin to a further late Miocene decline in CO2 that gave C4 grasses a photosynthetic advantage. This model is most appropriate for explaining replacement of C3 grasslands by C4 grasslands, however, fossil evidence shows C4 grasslands replaced woodlands. An additional weakness in the threshold model is that recent estimates do not support a late Miocene drop in pCO2. We hypothesize that late Miocene climate changes created a fire climate capable of replacing woodlands with C4 grasslands. Critical elements were seasonality that sustained high biomass production part of year, followed by a dry season that greatly reduced fuel moisture, coupled with a monsoon climate that generated abundant lightning-igniting fires. As woodlands became more open from burning, the high light conditions favoured C4 grasses over C3 grasses, and in a feedback process, the elevated productivity of C4 grasses increased highly combustible fuel loads that further increased fire activity. This hypothesis is supported by paleosol data that indicate the late Miocene expansion of C4 grasslands was the result of grassland expansion into more mesic environments and by charcoal sediment profiles that parallel the late Miocene expansion of C4 grasslands. Many contemporary C4 grasslands are fire dependent and are invaded by woodlands upon cessation of burning. Thus, we maintain that the factors driving the late Miocene expansion of C4 were the same as those responsible for maintenance of C4 grasslands today. [source] THE HISTORY OF A NEARCTIC COLONIZATION: MOLECULAR PHYLOGENETICS AND BIOGEOGRAPHY OF THE NEARCTIC TOADS (BUFO)EVOLUTION, Issue 11 2004Gregory B. Pauly Abstract Previous hypotheses of phylogenetic relationships among Nearctic toads (Bufonidae) and their congeners suggest contradictory biogeographic histories. These hypotheses argue that the Nearctic Bufo are: (1) a polyphyletic assemblage resulting from multiple colonizations from Africa; (2) a paraphyletic assemblage resulting from a single colonization event from South America with subsequent dispersal into Eurasia; or (3) a monophyletic group derived from the Neotropics. We obtained approximately 2.5 kb of mitochondrial DNA sequence data for the 12S, 16S, and intervening valine tRNA gene from 82 individuals representing 56 species and used parametric bootstrapping to test hypotheses of the biogeographic history of the Nearctic Bufo. We find that the Nearctic species of Bufo are monophyletic and nested within a large clade of New World Bufo to the exclusion of Eurasian and African taxa. This suggests that Nearctic Bufo result from a single colonization from the Neotropics. More generally, we demonstrate the utility of parametric bootstrapping for testing alternative biogeographic hypotheses. Through parametric bootstrapping, we refute several previously published biogeographic hypotheses regarding Bufo. These previous studies may have been influenced by homoplasy in osteological characters. Given the Neotropical origin for Nearctic Bufo, we examine current distributional patterns to assess whether the Nearctic-Neotropical boundary is a broad transition zone or a narrow boundary. We also survey fossil and paleogeographic evidence to examine potential Tertiary and Cretaceous dispersal routes, including the Paleocene Isthmian Link, the Antillean and Aves Ridges, and the current Central American Land Bridge, that may have allowed colonization of the Nearctic. [source] Lesbosoxylon gen. nov., eine neue Morphogattung mit dem Typus Lesbosoxylon ventricosuradiatum sp. nova aus dem Tertiär der Insel Lesbos, GriechenlandFEDDES REPERTORIUM, Issue 1-2 2010Herbert Süss Professor Dr. Für Protopinaceae-Hölzer aus dem Tertiär von Lesbos mit der Merkmalskombination "nur vertikale Harzgänge und große Holzstrahlen mit Idioblast-artigen Zellen" wird die Morphogattung Lesbosoxylon gen. nov. aufgestellt und der Typus L. ventricosuradiatum sp. nova beschrieben. Die mit dieser Merkmalskombination von Süss & Velitzelos (1994, 2009) als Pinoxylon -Arten der Insel Lesbos beschriebenen Fossilien werden zu Lesbosoxylon gestellt. Der Erhaltungszustand des Fundstücks und die Besonderheiten der Morphogattung Lesbosoxylon gen. nov. werden in eigenen Kapiteln besprochen (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Lesbosoxylon gen. nov., a new morphogenus with the typus Lesbosoxylon ventricosuradiatum sp. nova from the Tertiary of the Isle of Lesbos, Greece For Protopinaceae-woods from the Tertiary of Lesbos with the combination of features "only vertical resin channels and big rays with idioblast-like cells" the morphogenus Lesbosoxylon gen. nov. are put up and the typus L. ventricosuradiatum sp. nova described. The fossils described by Süss & Velitzelos (1994, 2009) as Pinoxylon -species with this combination of features are now placed to Lesbosoxylon. The maintenance of the fossil and the details of the morphogenus Lebosoxylon are described in separate chapters. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Rhodomyrtophyllum reticulosum (Rossm.) Knobloch & Z. Kva,ek , ein bedeutendes eozänes Florenelement im Tertiär MitteleuropasFEDDES REPERTORIUM, Issue 1-2 2003U. Glinka Dipl.-Biol. Nach kritischer Überprüfung blattepidermaler und blattmorphologischer Merkmalskomplexe an Blättern und Blattresten von RhodomyrtophyllumRüffle & Jähnichen aus dem Weißelster-Becken und seiner Randgebiete in Mitteldeutschland (Raum Halle,Leipzig,Borna,Altenburg,Zeitz,Zwickau und Ostthüringen) wird nachgewiesen, dass es sich bei den Blattresten um Vertreter einer einzigen Art handelt. Die Untersuchungen stützen sich auf 465 Fossilien aus meist kohlig- oder tonig-schluffiger Facies. In einer erweiterten Diagnose wird neben Grundformen mit typischen Charakteristiken die morphologische und blattanatomische Variationsbreite angeführt, die in den natürlichen Grenzen einer Species liegt. Untersuchungen an Blättern weiterer Fundorte in Europa kommen zum gleichen Ergebnis. An Arten von 21 Gattungen rezenter Myrtaceae erfolgen detaillierte Untersuchungen der Blattmorphologie und vor allem der Epidermisstruktur, die markante Ähnlichkeiten zur fossilen Sippe zeigen, was besonders bei Arten der Gattungen SyzygiumGaertn. und Eugenia L. erkennbar ist. Rhodomyrtophyllum reticulosum (Rossm.) Knobloch & Z. Kva,ek , a significant Eocene floral element in the Tertiary of Central Europe The leaf remains of RhodomyrtophyllumRüffle & Jähnichen from the Eocene occurring in the Weißelster Basin in central Germany (area Halle,Leipzig,Borna,Altenburg,Zeitz,Zwickau and Eastern Thuringia) have been proven to belong to a single species. This has been documented by analysing gross morphology and epidermical structure of 465 fossil leaves and leaf fragments from coal sand coal-silt facies. An emended diagnosis characterises besides basic forms with typical gross morphology and leaf anatomy, also extreme specimens within the limits of natural variability of Rhodomyrtophyllumreticulosum. These results correspond with studies from other European localities. Furthermore, detailed analyses of leaf morphology and epidermal structure of 21 recent species of the Myrtaceae are given. These demonstrate analogies of the fossil taxon studied especially among representatives of SyzygiumGaertn. and Eugenia L. [source] Piceoxylon pseudotsugae GOTHAN emend.FEDDES REPERTORIUM, Issue 1 2001Deutschland, VAN DER BURGH aus dem Obermiozän von Ottendorf-Okrilla bei Dresden 1987 konnte im Westteil der Kiesgrube Ottendorf-Okrilla (höheres Obermiozän) aus Tonen mit kohligen Schmitzen ein 1,14 m langer Stammrest geborgen werden. Er wird als Piceoxylon pseudotsugae Gothan 1906 emend, van der Burgh (1973) bestimmt. Das fossile Holz zeigt große Ähnlichkeit mit der heute noch im pazifischen Nordamerika beheimateten Pseudotsuga menziesii (Mirb.) Franco. Xylotomische Nachweise dieser Art sind bis heute nur wenige bekannt. Sie stammen aus Nordamerika, Deutschland (Rheinland), Österreich und Slask (Schlesien/Polen). Zu der anatomischen Beschreibung des Holzes wird die Ökologie der rezenten und die Paläookologie der fossilen Pseudotsuga diskutiert. Piceoxylon pseudotsugae Gothan emend. Van der Burgh from the Upper Miocene from Ottendorf-Okrilla near Dresden, Germany. A fossil wood, collected in Ottendorf-Okrilla by H. Kubasch, Kamenz, is described in this paper. It is identified by the first author as Piceoxylon pseudotsugae Gothan 1906 emend, van der Burgh 1973 because of its clear spiral thickenings in the tracheids (early and late wood) together with vertical and horizontal resin ducts. Tertiary wood assigned to this species is up till now only known from a few localities in North America and Europe (Rheinland/Germany, Austria, Silesia/Poland). The recent comparable species, Pseudotsuga menziesii (Mirb.) Franco, is known from a wide variety of localities in North America, with a very variable range concerning temperature. It is a tree of well drained, slightly acidic soils, preferably on sedimentary rocks with a volcanic or glacial origin. In the Tertiary of Europe this tree is also known from brown coal deposits. Therefore, for the Tertiary species a habitat in swamp environment must be added. [source] Mantle-derived and crustal melts dichotomy in northern Greece: spatiotemporal and geodynamic implicationsGEOLOGICAL JOURNAL, Issue 1 2004Diego Perugini Abstract Two distinct groups of subduction-related (orogenic) granitoid rocks, one Jurassic and the other Tertiary, occur in the area between the Vardar (Axios) Zone and the Rhodope Massif in northern Greece. The two groups of granitoids differ in many respects. The first group shows evolved geochemical characters, it is not associated with mafic facies, and evidence of magmatic interaction between mantle- and crustal-derived melts is lacking. The second group has less evolved geochemical characters, it is associated with larger amount of mafic facies, and magmatic interaction processes between mantle-derived and crustal melts are ubiquitous as evidenced by mafic microgranular enclaves and synplutonic dykes showing different enrichment in K2O, Ti, and incompatible elements. This kind of magmatism can be attributed to the complex geodynamic evolution of the area. In particular, we suggest that two successive subduction events related to the closure of the Vardar and the Pindos oceans, respectively, occurred in the investigated area from Late Jurassic to Tertiary. We relate the genesis of Jurassic granitoids to the first subduction event, whereas Tertiary granitoids are associated with the second subduction. Fluids released by the two subducted slabs induced metasomatic processes generating a ,leopard skin' mantle wedge able to produce mafic melts ranging from typical calc-alkaline to ultra-potassic. Such melts interacted in various amounts with crustal calc-alkaline anatectic melts to generate the wide spectrum of Tertiary granitoids occurring in the study area. Copyright © 2004 John Wiley & Sons, Ltd. [source] Constraints on deformation mechanisms during folding provided by rock physical properties: a case study at Sheep Mountain anticline (Wyoming, USA)GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2010K. Amrouch SUMMARY The Sheep Mountain anticline (Wyoming, USA) is a well-exposed asymmetric, basement-cored anticline that formed during the Laramide orogeny in the early Tertiary. In order to unravel the history of strain during folding, we carried out combined anisotropy of magnetic susceptibility (AMS), anisotropy of P -wave velocity (APWV) and Fry strain analyses. The results are compared to previously published stress,strain data from calcite twins at the microscopic scale and from fracture sets at the mesoscopic scale, and are used to discuss the kinematics and mechanics of forced folding. The results obtained in sandstone and carbonate lithologies demonstrate a good agreement between (1) the principal axes of the AMS and APWV tensors, (2) stress,strain tensors derived from calcite twins, (3) Fry strain axes and mesoscopic fracture sets. Furthermore, these tensors are coaxial with the main structural trends of the anticline. The differences between AMS and APWV fabrics on one hand, and the differential stress values of the forelimb and the backlimb on the other hand, emphasize how the macroscopic asymmetry of Sheep Mountain anticline affects the strain pattern at the microscopic scale. The data set presented in this paper offers a consistent mechanical scenario for the development of Sheep Mountain anticline. [source] The cation and silica chemistry of a Subandean river basin in western AmazoniaHYDROLOGICAL PROCESSES, Issue 7 2002J. A. Sobieraj Abstract We sampled river water at 13 locations in the Pichis basin, a 10 500 km2 large rainforest-covered drainage basin in Peru, to assess the influence of lithological variability and seasonality on water chemistry. The concentrations of major cations and silica show a strong seasonal dependence and a remarkable variability over short distances that is only weakly reduced in the wet season; cation concentrations in streams differ by up to 100% within a few kilometres. The lowest cation concentrations were associated with relatively cation-depleted upper Tertiary and lower Quaternary formations, whereas relatively cation-rich lower Tertiary and Jurassic formations left a clear calcium and sodium signal in the respective rivers. Cluster analysis, in conjunction with boxplots, suggests that the sampling locations can be segregated into three groups based on similarities of their geochemical signals. According to the previously defined criteria, one river is classified as a Group 2 river with 200 < TZ+ < 450 µeq/L, whereas all other rivers fall into Group 3 with 450 < TZ+ < 3000 µeq/L (where TZ+ refers to the total cation charge). Based on a comparison with other studies at different sections of the Amazon mainstem, the river chemistry of our study area is relatively enriched in K+, Mg2+ and Ca2+, and, consequently, has a higher TZ+ value, while being relatively depleted in silica. The influence of lithological variability on water chemistry must be considered in land-use change studies even at watershed areas of 26,3382 km2. Copyright © 2002 John Wiley & Sons, Ltd. [source] Phylogeny of major lineages of suboscines (Passeriformes) analysed by nuclear DNA sequence dataJOURNAL OF AVIAN BIOLOGY, Issue 1 2001Martin Irestedt Phylogenetic relationships among major groups of passeriform birds were studied by analyses of nucleotide sequence data from two nuclear genes, c- myc and RAG-1. The results corroborated both the monophyly of the order Passeriformes, and the major dichotomy into oscine and suboscine passerines previously suggested based on syringeal morphology and DNA-DNA hybridizations. The representatives of the Old World suboscines (families Eurylaimidae, Philepittidae and Pittidae) formed a monophyletic clade. The New World suboscines clustered into two clades. The first contained Conopophaga (Conopophagidae), Furnarius (Furnariidae), Lepidocolaptes (Dendrocolaptidae), Thamnophilus (Formicariidae), and Rhinocrypta (Rhinocryptidae). Previously, the monophyly of this group has been inferred from their possession of a unique, "tracheophone" syrinx, and from DNA-DNA hybridisation data. The second clade of New World suboscines includes Gubernetes and Muscivora (Tyrannidae), Phytotoma (Phytotomidae), Tityra (Cotingidae) and Pipra (Pipridae). This group of families have been considered monophyletic based on morphology (although ambiguously) and DNA-DNA hybridisation. The sister group relationship of Tityra and Phytotoma supports the previously supposed cotingid affinity of Phytotoma. Nuclear DNA data also unambiguously group the lyrebirds Menura with the oscines. The presented results from the analysis of nuclear DNA agree well with morphology and DNA-DNA hybridisation data. The precise age of the divergences studied herein are unknown but based on interpretations of the fossil record of passerine birds many of them might date back to the early Tertiary. The agreement between data from the nuclear DNA and other sources, along with the fact that neither of the studied genes showed sign of saturation, indicate the great potential of these two nuclear genes to resolve very old divergences in birds. [source] Process in the evolution of bird migration and pattern in avian ecogeographyJOURNAL OF AVIAN BIOLOGY, Issue 2 2000Christopher P. Bell Current ideas about the evolution of bird migration equate its origin with the first appearance of fully migratory populations, and attribute its evolution to a selective advantage generated by increased breeding success, gained through temporary emigration from resident populations to breed in under-exploited seasonal areas. I propose an alternative hypothesis in which migration first appears as a temporary directional shift away from the breeding site outside the reproductive period, in response to seasonal variation in the direction and/or severity of environmental gradients. Fully migratory populations then appear through either extinction of sedentary phenotypes, or colonisation of vacant seasonal areas by migrants. Where colonisation occurs, resident ancestral populations can be driven to extinction by competition from migrants which invade their range outside the breeding season, resulting in fully migratory species. An analogous process drives the evolution of migration between high latitudes and the tropics, since extension of breeding range into higher latitudes may drive low latitude populations to extinction, resulting in an overall shift of breeding range. This process can explain reverse latitudinal gradients in avian diversity in the temperate zone, since the breeding ranges of migratory species concentrate in latitudes where they enjoy the highest breeding success. Near absence of forest-dwelling species among Palaearctic-African migrants is attributable to the lack of forest in northern Africa for much of the Tertiary, which has precluded selection both for southward extension of migration by west Palaearctic forest species, and northward breeding colonisation by African forest species. [source] Evolution and biogeography of the austral genus Phyllocladus (Podocarpaceae)JOURNAL OF BIOGEOGRAPHY, Issue 10 2004Steven J. Wagstaff Abstract Aim, To infer evolutionary relationships within the genus Phyllocladus and among its close relatives by phylogenetic analysis of DNA sequences. Interpret the inferred relationships in association with the fossil record to examine the origin and diversification of the genus. Location, Australasia. Methods, Phylogenetic analyses of rbcL, matK and internal transcribed spacer (ITS) sequences representing all of the extant species of Phyllocladus and a selection of outgroups from Podocarpaceae and Araucariaceae. Results, The rbcL and matK sequences exhibit little variation within Phyllocladus, but ally its members to Podocarpaceae although its immediate sister remains unclear. The ITS sequences resolve all five species of Phyllocladus and two intraspecific ecotypes of P. alpinus. Main conclusions,Phyllocladus forms a distinct lineage that diverged early in the evolutionary history of Podocarpaceae. The fossil record indicates that the genus was more widely distributed and morphologically diverse during the early Tertiary than at present. Although of Mesozoic origin, the level of sequence variation within Phyllocladus suggests that the extant species radiated during the late Tertiary c. 6.3 ± 0.9 Ma. New Zealand is the present centre of species diversity. [source] A comparison of taiga flora in north-eastern Russia and Alaska/YukonJOURNAL OF BIOGEOGRAPHY, Issue 7 2003David K. Swanson Abstract Aim, To understand the similarities and differences between the taiga floras of far north-eastern Asia and north-western North America in the light of their Tertiary and Quaternary histories. Does the taiga flora follow the tundra pattern (Asian,American commonality of species as a result of continuity through the Quaternary), the temperate forest pattern (distinct species because of late Tertiary disjunction), a combination of these two patterns, or some pattern unique to the taiga? Location, The taiga regions of interior Alaska and the Yukon in North America (the ,Alaskan taiga'), and the Kolyma and eastern Indigirka River basins in Russia (the ,Kolyma taiga'). The study areas include both forested and unforested habitats below elevational treeline. The two regions have similar climate and topography and were linked via the Bering Land Bridge in the Tertiary and for several extended periods during Quaternary cold periods. Methods, Systematic comparison of the vascular floras of the two regions from published sources; and review of palaeoecological literature for the region. Results, Of the 796 species found in the study areas, 27% occur only in the Alaskan taiga, 35% occur only in the Kolyma taiga, and 38% occur in both the regions. The following subsets of species show a high proportion of species in common between the study areas (subsets are not mutually exclusive): plants that occur on the tundra and the taiga, non-flowering plants, abundant taiga understory plants, and wetland and aquatic plants. A lower proportion of shared plants was noted for warm, south-facing steppe communities. No tree species are common to both areas. Main conclusions, The Bering Strait region in the Quaternary has acted as a biogeographical filter for taiga plants. Significant divergence between northeast Asia and northwest North America has developed among the more southerly ranging fraction of the flora (e.g. trees), while the more cosmopolitan and the most cold-adapted elements of the taiga flora are common to both areas. Many plants in the former group have been disjunct between Asia and North America for millions of years, while many plants in the latter group have probably maintained continuity between the study areas via the Bering Land Bridge through much of the late Tertiary and Quaternary periods. Repeated extirpation of the less cold-adapted species from both study areas during Pleistocene cold periods has probably enhanced floristic differences between the two regions. [source] New perspectives on the origin and diversification of Africa's forest avifaunaAFRICAN JOURNAL OF ECOLOGY, Issue 3 2008Jon Fjeldså Abstract The use of DNA sequence data in systematic studies has brought about a revolution in our understanding of avian relationships and when combined with digitized distributional data, has facilitated new interpretations about the origins of diverse clades of the African avifauna including its diversification up through the Tertiary until the present. Here we review recent studies with special reference to Africa's forest avifauna and specifically comment on the putative origins of ,hotspots' of endemism in the Eastern Arc Mountains of Tanzania and in the Cape Region of South Africa. Intriguingly, both these areas appear to have retained populations of relict taxa since the mid-tertiary thermal optimum and at the same time have been centres of recent species differentiation. Résumé L'utilisation des données portant sur la séquence ADN dans les études systématiques représente une révolution dans notre façon de comprendre les relations entre les oiseaux et, combinée avec les données numérisées sur la distribution, elle facilite de nouvelles interprétations concernant les origines de différents clades de l'avifaune africaine, y compris sa diversification tout au long du Tertiaire et jusqu'à nos jours. Nous passons ici en revue des études récentes qui se réfèrent particulièrement à l'avifaune forestière africaine, avec un commentaire spécial sur les origines putatives des hauts lieux d'endémisme dans les montagnes de l'Eastern Arc tanzanien et dans la région du Cap, en Afrique du Sud. Curieusement, ces deux endroits semblent avoir conservé des populations de taxons résiduels depuis l'optimum thermique du milieu du Tertiaire, tout en étant aussi au centre de récentes différenciations entre espèces. [source] Fluid evolution and thermal structure in the rapidly exhuming gneiss complex of Namche Barwa,Gyala Peri, eastern Himalayan syntaxisJOURNAL OF METAMORPHIC GEOLOGY, Issue 9 2005D. CRAW Abstract High-grade gneisses (amphibolite,granulite facies) of the Namche Barwa and Gyala Peri massifs, in the eastern Himalayan syntaxis, have been unroofed from metamorphic depths in the late Tertiary,Recent. Rapid exhumation (2,5 mm year,1) has resulted in a pronounced shallow conductive thermal anomaly beneath the massifs and the intervening Tsangpo gorge. The position of the 300 °C isotherm has been estimated from fluid inclusions using CO2,H2O immiscibility phase equilibria to be between 2.5 and 6.2 km depth below surface. Hence, the near-surface average thermal gradient exceeds 50 °C km,1 beneath valleys, although the thermal gradient is relatively lower beneath the high mountains. The original metamorphic fluid in the gneisses was >90% CO2. This fluid was displaced by incursion of brines from overlying marine sedimentary rocks that have since been largely removed by erosion. Brines can exceed 60 wt% dissolved salts, and include Ca, Na, K and Fe chlorides. These brines were remobilized during the earliest stages of uplift at >500 °C. During exhumation, incursion of abundant topography-driven surface waters resulted in widespread fracture-controlled hydrothermal activity and brine dilution down to the brittle,ductile transition. Boiling water was particularly common at shallow levels (<2.5 km) beneath the Yarlung Tsangpo valley, and numerous hot springs occur at the surface in this valley. Dry steam is not a major feature of the hydrothermal system in the eastern syntaxis (in contrast to the western syntaxis at Nanga Parbat), but some dry steam fluids may have developed locally. [source] HYDROTHERMALLY FLUORITIZED ORDOVICIAN CARBONATES AS RESERVOIR ROCKS IN THE TAZHONG AREA, CENTRALTARIM BASIN, NW CHINAJOURNAL OF PETROLEUM GEOLOGY, Issue 1 2006Zhijun Jin Reservoir rocks at the Tazhong 45 oil pool, central Tarim Basin, consist of fluoritized carbonate strata of Middle - Late Ordovician age. Petrological observations indicate that the fluorite replaces calcite. Several other hydrothermal minerals including pyrite, quartz, sphalerite and chlorite accompany the fluorite. Two generations of fluid inclusions are present in the fluorite. Homogenization temperatures (Th) for primary inclusions are mostly between 260°C and 310°C and represent the temperature of the hydrothermal fluid responsible for fluorite precipitation. Th for secondary inclusions range from 100°C to 130°C, and represent the hydrocarbon charging temperature as shown by the presence of hydrocarbons trapped in some secondary inclusions. The mineral assemblage and the homogenization temperatures of the primary fluid inclusions indicate that the precipitation of fluorite is related to hydrothermal activity in the Tazhong area. Strontium isotope analyses imply that the hydrothermal fluids responsible for fluorite precipitation are related to late-stage magmatic activity, and felsic magmas were generated by mixing of mafic magma and crustal materials during the Permian. Theoretical calculations show that the molecular volume of a carbonate rock decreases by 33.5% when calcite is replaced by fluorite, and the volume shrinkage can greatly enhance reservoir porosity by the formation of abundant intercrystalline pores. Fluoritization has thus greatly enhanced the reservoir quality of Ordovician carbonates in the Tazhong 45 area, so that the fluorite and limestone host rocks have become an efficient hydrocarbon reservoir. According to the modelled burial and thermal history of the Tazhong 45 well, and the homogenization temperatures of secondary fluid inclusions in the fluorite, hydrocarbon charging at the Tazhong 45 reservoir took place in the Tertiary. [source] THE STRUCTURAL STYLE OF SEDIMENTARY BASINS ON THE SHELVES OF THE LAPTEV SEA AND WESTERN EAST SIBERIAN SEA, SIBERIAN ARCTICJOURNAL OF PETROLEUM GEOLOGY, Issue 3 2005D. Franke A total of 11,700 km of multichannel seismic reflection data were acquired during three recent reconnaissance surveys of the wide, shallow shelves of the Laptev and western East Siberian Seas in the Siberian Arctic Ocean. Three seismic marker horizons were defined and mapped in both shelf areas. Their nature and age were predicted on the basis of regional tectonic and palaeoenvironmental events and corroborated using onshore geology. To the north of the Laptev Sea, the Gakkel Ridge, an active mid-ocean ridge which separates the North American and Eurasian Plates, abruptly meets the steep slope of the continental shelf which is curvilinear in plan view. Extension has affected the Laptev Shelf since at least the Early Tertiary and has resulted in the formation of three major, generally north-south trending rift basins: the Ust'Lena Rift, the Anisin Basin and the New Siberian Basin. The Ust'Lena Rift has a minimum east-west width of 300km at latitude 75°N and a Cenozoic infill up to 6 s (twt) in thickness. Further to the NW of the Laptev Shelf, the downthrown and faulted basement is overlain by a sub-parallel layered sedimentary succession with a thickness of 4 s (twt) that thins towards the west. Although this area was affected by extension as shown by the presence of numerous faults, it is not clear whether this depression on the NW Laptev Shelf is continuous with the Ust'Lena Rift. The Anisin Basin is located in the northern part of the Laptev Shelf and has a Cenozoic sedimentary fill up to 5 s (twt) thick. The deepest part of the basin trends north-south. To the west is a secondary, NW-SE trending depression which is slightly shallower than the main depocentre. The overall structure of the basin is a half-graben with the major bounding fault in the east. The New Siberian Basin is up to 70 km wide and has a minimum NW-SE extent of 300 km. The sedimentary fill is up to 4.5 s (twt) thick. Structurally, the basin is a half-graben with the bounding fault in the east. Our data indicate that the rift basins on the Laptev Shelf are not continuous with those on the East Siberian Shelf. The latter shelf can best be described as an epicontinental platform which has undergone continuous subsidence since the Late Cretaceous. The greatest subsidence occurred in the NE, as manifested by a major depocentre filled with inferred (?)Late Cretaceous to Tertiary sediments up to 5 s (twt) thick. [source] POTENTIAL STRUCTURAL TRAPS ASSOCIATED WITH LOWER CARBONIFEROUS SALT IN THE NORTHERN TARIM BASIN, NW CHINAJOURNAL OF PETROLEUM GEOLOGY, Issue 1 2004Jiangyu Zhou In the Aixieke-Santamu area of the northern Tarim Basin (NW China), 45 relatively low amplitude structures related to the plastic flow of Lower Carboniferous salt have been discovered in the Lower Carboniferous Kalashayi Formation and the Middle-Upper Triassic Akekule and Halahatan Formations. Three small hydrocarbon accumulations have so far been located at the margins of a Lower Carboniferous salt body (measuring about 55km x 75km and 115,225m thick, controlled by wells and 2D and 3D seismic sections). In this paper, we consider the development of this salt body and discuss possible reasons why vertical diapirs are absent from the study area. We attempt to develop a model of salt flow and we investigate the relationship between salt flow and the occurrence of oil and gas traps. Using recently-acquired high-resolution 2D and 3D seismic profiles, we show that the Lower Carboniferous salt has undergone three separate phases of plastic flow. At the end of the Early Permian, the salt flowed southwards by 2.0,2.8 km; then, during the Late Triassic,Early Jurassic, it flowed in the same direction by 1.0,1.8 km; and finally at the end of the Tertiary, it flowed northwards by 0.6,1.5 km. These movements resulted in the formation of various types of structural trap in the Kalashayi, Akekule and Halahatan Formations including salt ridge anticlines, domes and marginal troughs. Salt ridge and salt edge low-amplitude anticlines are probably the most important targets for future hydrocarbon exploration. [source] BURIAL AND MATURATION HISTORY OF THE HEGLIG FIELD AREA, MUGLAD BASIN, SUDANJOURNAL OF PETROLEUM GEOLOGY, Issue 1 2000A. Y. Mohamed The NW-SE trending Muglad Basin (SW Sudan) is one of a number of Mesozoic basins which together make up the Central African Rift System. Three phases of rifting occurred during the Cretaceous and Tertiary, resulting in the deposition of at least 13 km of sediments in this basin. Commercial hydrocarbons are sourced from the Barremian-Neocomian Sharaf Formation and the Aptian-Albian Abu Gabra Formation. The Heglig field is located on a NW-SE oriented structural high in the SE of the Muglad Basin, and is the second-largest commercial oil discovery in Sudan. The high is characterised by the presence of rotated fault blocks, and is surrounded by sub-basinal structural lows. We modelled the geohistories of three wells on different fault blocks in the Heglig field (Heglig-2, Barki-1 and Kanga-1) and one well in the Kaikang Trough (May25,1). The models were calibrated to measured porosity-depth data, temperature and vitrinite reflectance measurements. Predicted present-day heat flow over this part of the Muglad Basin is about 55 mW/m2. However, a constant heat-flow model with this value did not result in a good fit between calculated vitrinite Ro and measured Ro at the wells studied. Therefore a variable heat-flow model was used; heat flow peaks of 75, 70 and 70 mW/m2 were modelled, these maxima corresponding to the three synrift phases. This model resulted in a better fit between calculated and measured Ro. The source rock section in the Sharaf and Abu Gabra Formations was modelled for hydrocarbon generation in the four wells. Model results indicate that the present-day oil generation window in the Hegligfield area lies at depths of between 2 and 4 km, and that oil and gas generation from the basal unit of the Abu Gabra Formation occurred between about 90 and 55 Ma and from the Sharaf Formation between 120 and 50 Ma. The results suggest that the oils discovered in the Heglig area have been generated from a deep, mature as-yet unpenetrated source-rock section, and/or from source rocks in nearby sub- basinal areas. [source] The structural evolution of the English Channel areaJOURNAL OF QUATERNARY SCIENCE, Issue 3-4 2003J. L. Lagarde Abstract The structural evolution of the English Channel area is controlled by structure and particularly by the pre-existing Cadomian and Variscan crustal discontinuities, which have been reactivated repeatedly in post-Variscan times. They controlled the crustal subsidence that produced basin development in the Mesozoic, prior to the sea-floor spreading in the North Atlantic region. They were then reactivated during the Cenozoic compression and basin inversion. The English Channel development is ascribed to mid-Tertiary differential uplift (Oligocene to Miocene). During late Tertiary to Quaternary times the Channel displays characteristics of a tectonically controlled fluvial basin periodically invaded by the sea. At the lithospheric scale, the Channel can be considered as an active intraplate area influenced by the NW,SE ,Alpine push', the NW,SE ,Atlantic ridge push' and glacial rebound stresses. Copyright © 2003 John Wiley & Sons, Ltd. [source] Evolution of the Madrean,Tethyan disjunctions and the North and South American amphitropical disjunctions in plantsJOURNAL OF SYSTEMATICS EVOLUTION, Issue 5 2009Jun WEN Abstract, The present paper reviews advances in the study of two major intercontinental disjunct biogeographic patterns: (i) between Eurasian and western North American deserts with the Mediterranean climate (the Madrean,Tethyan disjunctions); and (ii) between the temperate regions of North and South America (the amphitropical disjunctions). Both disjunct patterns have multiple times of origin. The amphitropical disjunctions have largely resulted from long-distance dispersal, primarily from the Miocene to the Holocene, with available data indicating that most lineages dispersed from North to South America. Results of recent studies on the Mediterranean disjuncts between the deserts of Eurasia and western North America support the multiple modes of origin and are mostly consistent with hypotheses of long-distance dispersal and the North Atlantic migration. Axelrod's Madrean,Tethyan hypothesis, which implies vicariance between the two regions in the early Tertiary, has been favored by a few studies. The Beringian migration corridor for semiarid taxa is also supported in some cases. [source] Spiders in Upper Cretaceous Amber from New Jersey (Arthropoda: Araneae)PALAEONTOLOGY, Issue 4 2002David Penney The oldest described fossils of the extant spider families Segestriidae, Oonopidae, Oecobiidae, Dictynidae and Linyphiidae, previously known from the Tertiary, are presented from Upper Cretaceous amber of New Jersey. The third and oldest known specimen of the fossil spider family Lagonomegopidae is also described and provides further palaeontological evidence of a common Laurasian fauna. The extant genera Segestria and Oecobius are taken back a further 52 and 69,74 myr respectively in the fossil record. These fossils predict the presence of the Caponiidae, Tetrablemmidae, Orsolobidae, Dysderidae, Hersiliidae, Eresidae, Pimoidae, Scytodoidea s.l., cyatholipoids, theridioids and symphytognathoids in the Cretaceous. They also extend the known geological range of extant spider families through and beyond the end,Cretaceous extinction. This event, which affected numerous marine and some terrestrial organisms, probably had little effect on the Araneae. [source] Provenance Of Atlantic Lingulid BrachiopodsPALAEONTOLOGY, Issue 6 2000Alwyn Williams Living lingulid brachiopods are ubiquitous in low-latitude, marine infaunas. Lingula occurs throughout the Pacific and Indian oceans with the only Atlantic species, L. parva, confined to West Africa. Glottidia is restricted to offshore America from Virginia to California and Peru, and is assumed to have descended from a Pacific Lingula during the early Tertiary. Lingulid organophosphatic shells differ structurally. That of Glottidia is characterizedby trellised rods (baculate); that of Indo-Pacific species of Lingula by spheroidal and rod-like microstructures (virgose); and that of L. parva by apatitic rods arranged as spherulites. A spherulitic fabric is unknown in fossil lingulids, but the distinction between GlottidiaLingula can be traced back to the Carboniferous, which accords with the deep molecular divergence between the two genera. The common occurrence of lingulids with baculate shells in European post-Palaeozoic sediments suggests that ancestral Glottidia entered the Atlantic by the Tethyan Current during the Late Cretaceous/early Cenozoic, and migrated into the Pacific before the formation of the Panama Isthmus. Penecontemporaneously, antecedents of L. parva possibly migrated from east Tethys along the trans-Saharan seaway. [source] Opisthobranch molluscs from the Tertiary of the Aquitaine Basin (south-western France), with descriptions of seven new species and a new genusPALAEONTOLOGY, Issue 3 2000Ángel Valdés An exceptionally well-preserved collection of Tertiary opisthobranch molluscs from the Aquitaine Basin, France, includes species of the order Notaspidea [Umbraculum sanctipaulensis sp. nov., Tylodina perversa (Gmelin), Spiricella unguiculus Rang and Des Moulins, Berthella aquitaniensis sp. nov., Berthella ateles sp. nov.], of the order Anaspidea [Akera cf. bullata Mu¨ller, Floribella corrugata (Cossmann), Floribella cossmanni sp. nov., Floribella rozieri sp. nov., Limondinia ornata gen. et sp. nov.] and of the order Sacoglossa [Volvatella faviae sp. nov.]. BerthellaaquitaniensisB. atelesV. faviae are the first fossil records of the families Volvatellidae and Pleurobranchidae. Floribella plicifera (Cossmann) and F.corrugata, originally assigned to the genus Philine, belong to the genus Floribella and constitute the oldest records of this genus. The fossil evidence indicates that in Umbraculum laudunensis and U. sanctipaulensis the shell probably covered most of the animal, whereas in the Recent U. umbraculum the shell only covers the central portion of the body. Tylodina perversa could be an old species that appeared during the early Miocene, more than 21 Ma. The Recent shells of Akera bullata are indistinguishable from fossils as old as the mid Eocene, but it may be biologically unrealistic to consider them to be the same species. The European species of Floribella evolved from the bullomorph shells of the early Eocene forms to the elongate shells of the early Miocene. The genus Volvatella is another example of marine tropical disjoint distributions and an excellent ecological indicator. [source] Geological and Geochemical Characteristics of the Hydrothermal Clay Alteration in South KoreaRESOURCE GEOLOGY, Issue 4 2000Sang-Mo KOH Abstract: Hydrothermally altered areas forming pyrophyllite-kaolin-sericite-alunite deposits are distributed in Chonnam and Kyongsang areas, Cretaceous volcanic field of the Yuchon Group. The Chonnam alteration area is located within depression zone which is composed of volcanic and granitic rocks of late Cretaceous age. The clay deposits of this area show the genetic relationship with silicic lava domes. The Kyongsang alteration area is mainly distributed within Kyongsang Basin comprising volcanic, sedimentary and granitic rocks of Cretaceous and Tertiary age. Most of the clay deposits of this area are closely related to cauldrons. Paleozoic clay deposit occurs in the contact zone between Precambrian Hongjesa granite gneiss and Paleozoic Jangsan quartzite of Choson Supergroup. Cretaceous igneous rocks of the both alteration areas belong to high K calc-alkaline series formed in the volcanic arc of continental margin by subduction-related magmatism. Chonnam igneous rocks show more enrichment of crustal components such as K, La, Ce, Sm, Nd and Ba, higher (La/Yb)cn ratio, and higher initial 87Sr/86Sr ratio (0. 708 to 0. 712) than those of Kyongsang igneous rocks. This might be due to the difference of degree of crustal contamination during Cretaceous magmatism. The most characteristic alteration minerals of Chonnam clay deposits are alunite, kaolin, quartz, pyrophyllite and diaspore which were formed by acidic solution. Those of Kyongsang clay deposits are sericite, quartz and pyrophyllite which were formed by weak acid and neutral solution. The formation ages of the clay deposits of two alteration areas range from 70. 1 to 81. 4 Ma and 39. 7 to 79. 4 Ma, respectively. The Daehyun clay deposit in Ponghwa area of Kyongsang province shows the alteration age range from 290 to 336 Ma. This result shows the different alteration episode from the hydrothermal alteration of Cretaceous to early Tertiary in the Kyongsang and Chonnam alteration areas. These data indicate, at least, three hydrothermal activities of Tertiary (middle to late Eocene), late Cretaceous (Santonian to Maastrichtian) and Paleozoic Carboniferous Periods in South Korea. [source] Efficient Catalytic Synthesis of Tertiary and Secondary Amines from Alcohols and Urea,ANGEWANDTE CHEMIE, Issue 52 2009Jinling He Dr. Harnstoff als Stickstoffquelle: Trägerfixiertes Rutheniumhydroxid, Ru(OH)x/TiO2, dient in der Titelreaktion als effizienter Heterogenkatalysator. Der nach der Reaktion zurückgewonnene Katalysator konnte ohne merklichen Verlust an katalytischer Aktivität wiederverwendet werden. [source] Kinetic Resolution of Quaternary and Tertiary ,-Hydroxy Esters,ANGEWANDTE CHEMIE, Issue 44 2009Derek Einfach selektiv: In Gegenwart von (1S,2R)- N -methylephedrin gelingt die Racematspaltung von tertiären und sekundären Alkoholen, die bei Aldoladditionen mit Ketonen und Aldehyden entstehen (siehe Beispiel). Die Methode ist einfach ausführbar und leicht auf einen größeren Maßstab zu übertragen, und sie liefert tertiäre und sekundäre Alkohole mit hohen Enantiomerenverhältnissen. [source] Modelling Students at RiskAUSTRALIAN ECONOMIC PAPERS, Issue 2 2004Diane M. Dancer Using a sample of several hundred students we model progression in a first-year econometrics course. Our primary interest is in determining the usefulness of these models in the identification of ,students at risk'. This interest highlights the need to distinguish between students who drop the course and those who complete but who ultimately fail. Such models allow identification and quantification of the factors that are most important in determining student progression and thus make them a potentially useful aid in educational decision making. Our main findings are that Tertiary Entrance Rank (TER), mathematical aptitude, being female and attendance in tutorials are all good predictors of success but amongst these factors only attendance is significant in discriminating between students who fail and those who discontinue. Also, there are differences across degree programs and, in particular, students in Combined Law are very likely to pass but, if they are at risk, they are much more likely to discontinue than to fail. [source] | ||||||||||||||||||||||||||||||||||||||||||||||