Synapsiden erscheinen erstmals im Fossilbericht im Oberkarbon (späten Pennsylvanium) und dominierten terrestrische Ökosysteme bis zum Ende des Paläozoikums. Diese Arbeit ist die erste detaillierte Betrachtung der frühen Evolution der Synapsiden. Modifizierte Versionen zuvor publizierter Vollständigkeitsmaße werden benutzt, um die Vollständigkeit von Pelycosaurier Fossilien einzuschätzen. Zudem wird eine Reihe unterschiedlicher Methoden genutzt, um die Übereinstimmung von Fossilbericht und Phylogenese zu messen. Die Vollständigkeitsanalyse der Pelycosaurier zeigt eine negative Korrelation zwischen Diversität und dem Maß der Merkmalsvollständigkeit, was darauf hindeutet, dass viele Spezies auf unvollständig erhaltenem Material basieren. Die fehlende Korrelation zwischen dem Maß zur Merkmalsvollständigkeit (basierend auf Abschätzung der Proportion phylogenetisch erfassbarer Merkmale) und der Diversität wird auf die Entdeckungsgeschichte der Gruppe zurück geführt: Die Mehrheit der Pelycosaurier-Arten wurden zwischen den 1930er und 1960er Jahren benannt, als taxonomische Zuordnungen häufig auf Körpergrösse, Fundort und Stratigraphie anstatt auf morphologischen Merkmalen basierten. Welche Schätzungen der Artenzahl über die Erdgeschichte beinflussen, produzieren die unterschiedlichen Methoden zur Diversitätsrekonstruktion sehr ähnliche Ergebnisse. Der initialen Diversifikation der Synapsiden im Oberkarbon und Unterperm (frühes Cisuralium) folgte ein Aussterbeereignis während des Sakmariums. Ein zweites Aussterben ereignete sich an der Grenze vom Kungurium zum Roadium. Die phylogenetisch Topologie-Analyse keine signifikanten Steigerungen der Diversitätsrate der Pelycosaurier relativ zu zeitgleich lebenden Taxa. Eine breiter angelegte Auswertung der Diversitätsentwicklung paläozoischer und triassischer Amnioten liefert ein mögliches Erklärungsmodell; Veränderungen der Diversitätsraten früher Amnioten tendieren dazu, zu Zeiten erhöhter Aussterberaten aufzutreten. / Synapsids first appear in the fossil record during the late Pennsylvanian, and dominated the terrestrial realm until the end of the Palaeozoic. This thesis provides the first detailed examination of the earliest evolution of synapsids. Modifications of previously published metrics are used to assess the completeness of their specimens, and a variety of methods are employed to measure the fit of the fossil record to the phylogeny. The analysis into the completeness of pelycosaurian-grade specimens reveals a negative correlation between diversity and the Skeletal Completeness Metric, assessing the bulk of material preserved, suggesting a tendency to name many species based on poor material. The lack of correlation between the Character Completeness Metric (assessing the proportion of phylogenetic characters that can be scored) and diversity is attributed to the history of discovery in the group: the majority of pelycosaurian-grade species were named between the 1930s and 1960s, when assignments were often based on size, location and stratigraphy rather than morphological characters. The different methods of assessing diversity provide very similar results. The initial diversification of synapsids in the Late Pennsylvanian and early Cisuralian was followed by an extinction event during the Sakmarian. A second extinction event occurred across the Kungurian/Roadian boundary. The tree topology analysis found no significant increases in diversification rate occurring in pelycosaurian-grade taxa relative to their contemporaries. A broader examination of diversification patterns in Palaeozoic and Triassic amniotes reveals a possible explanation; diversification rate shifts within early amniotes tend to occur during periods of elevated extinction.

No description available.

The oldest sedimentary and metasedimentary rocks exposed in the Himalayan foothills of Pakistan record a gradual transition seaward from the evaporites of the Salt Range Formation to pelitic sediments deposited in deeper water to the north. The Upper Proterozoic Tanawal Formation was derived from erosion of a northern highland produced during the early stages of Late Proterozoic to early Ordovician tectonism. Early Paleozoic tectonism is indicated by an angular unconformity at the base of the Paleozoic section, the intrusion of the Mansehra Granite, and the local removal of Cambrian strata. Paleozoic shallow-marine strata are preserved in half-grabens created during extensional tectonism that began during the Carboniferous and climaxed with rifting during the Permian. Paleozoic rocks were largely or completely eroded from northwest-trending highlands on the landward side of the rift shoulder. Thermal subsidence of the rifted margin resulted in transgression of the highlands and deposition of a Mesozoic section dominated by carbonates. Compressional tectonism related to the impending collision with Asia commenced in the Late Cretaceous. Rocks north of the Panjal-Khairabad fault were deformed and metamorphosed during Eocene subduction of northern India beneath the Kohistan arc terrane. Following their uplift and exhumation, rocks metamorphosed beneath Kohistan were thrust southward over unmetamorphosed rocks along the Panjal and Khairabad faults which are inferred to be connected beneath alluvium of the Haripur basin. Contrasts in stratigraphy and metamorphism on either side of the Panjal-Khairabad fault indicate that shortening on this structure exceeds that of any other fault in the foothills region. The migration of deformation towards the foreland produced south- or southeast-vergent folds and thrust faults in strata south of the Panjal-Khairabad fault and reactivated Late Cretaceous structures such as the Hissartang fault. The Hissartang fault is the westward continuation of the Nathia Gali fault, a major structure that thrusts Proterozoic rocks in the axis of a Late Paleozoic rift highland southward over Mesozoic strata. Fundamental differences in stratigraphy, metamorphism, and relative displacement preclude straightforward correlation of faults and tectonic subdivisions of the central Himalaya of India and Nepal with the northwestern Himalaya of Pakistan. / Graduation date: 1994

Previous studies have identified δ¹³C events in the Carboniferous that imply major shifts in the carbon cycle. However, inherent in this interpretation is the assumption that epicontinental seas are chemically representative of the global ocean. Our study uses stable isotope and trace element analyses of brachiopod shells to examine changes in climate and circulation of the North American epeiric sea. Formations were selected for study to provide shallow marine environments with geographic coverage of North America. These units include the Grove Church and Mattoon Formations (Illinois Basin), Glenshaw Formation (Appalachian Basin), Bird Spring Formation (Bird Spring Basin), and Oread Formation (US midcontinent). In all, 98 brachiopod shells were found to be well preserved based on screening with plane light and cathodoluminescence microscopy of thin-sections, and trace element analyses. Upper Chesterian Grove Church (Illinois Basin) samples have δ¹³C and δ¹⁸O averages of 1.1% and -3.1% respectively. These low values are interpreted as a local or regional effect caused by terrestrial runoff. Terrestrial influences are also suggested by the depositional environment: nearshore marine. Chesterian samples from the Bird Spring Formation at Arrow Canyon, Nevada average 3.7% and -1.4% for δ¹³C and δ¹⁸O respectively. The higher δ¹³C and δ¹⁸O values, compared with samples from the time equivalent Grove Church, likely reflect the freer exchange with the Panthalassa Ocean at this most western edge of North America, and best represent open-ocean conditions. Samples from the Virgilian Ames-Shumway-Plattsmouth cyclothem show a progression of δ¹³C and δ¹⁸O enrichment moving west from near the Appalachians (1.9% and -3.8%) to the Illinois Basin (3.2% and -2.4%) and finally to the US midcontinent (4.2% and -1.5%). This is interpreted as the transition from nearshore, terrestrial influence with enhanced organic matter oxidation and lower salinity to well-mixed conditions with normal salinities and potential for seafloor ventilation and upwelling. This is supported by published sediment ΣNd(t) values from the Appalachian Basin (ΣNd(t) = -9) that increase further westward (ΣNd(t) = -6) due to higher influence from the eastern Panthalassa Ocean. Mass balance calculations based on the δ¹⁸O of the brachiopod shells suggest salinities of 25 and 31 psu for the Appalachian and Illinois Basins, respectively, assuming salinities of 34.5 psu for the US midcontinent. Trace element analyses do not show a systematic east-west trend similar to stable isotopes. In both time slices, spiriferids from the intermediately-located Illinois Basin are enriched in Mg/Ca and Sr/Ca relative to those in other basins. This Mg and Sr enrichment in Illinois Basin brachiopods suggests delivery of Sr-rich fresh waters and restricted circulation in that basin.

published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

A boulder bed unit in the upper Haymond Formation (Pennsylvanian), generally believed to be olistostromes, is exposed in the eastern Marathon Basin, west Texas. Two localities of this unit (Housetop Mountain and Clark Butte) contain clasts derived from several formations found within the basin, as well as exotic Devonian metamorphic and volcanic rocks. This report describes a third previously unstudied site (Martin Ranch locality) that contains clasts of exotic Middle Cambrian shelf limestones. These limestones provide a key to the Early Paleozoic history of the Marathon region. The boulder beds lie in the upper part of the Haymond Formation. At the Martin Ranch locality they form a zone that is traceable for 6.6 km along strike and is up to 230 m thick. These boulder beds contain interbedded units of massive, unstratified, pebble- to boulder-bearing mudstone, thickly bedded, massive sandstone, lenses of pebbly sandstone, and deformed flysch beds. About 80 percent of the clasts found in the boulder beds at Martin Ranch are chert derived from several basin formations. Unique displaced slabs of bedded chert pebble conglomerate comprise about 10 percent of the clasts. Theses conglomerates were probably derived from upper fan-channel deposits within the lower Haymond Formation. Pennsylvanian limestone clasts redeposited from the basin facies of the Dimple Formation and clasts of exotic, late Middle Cambrian limestones each comprise about 5 percent of the clasts. These Cambrian limestones, older than any formation in the Marathon Basin, contain a fauna characteristic of the seaward edge of the cratonic carbonate shelf. The presence of the Cambrian clasts constrains the location of the North American shelf edge during the Cambrian, placing it at least 120 km southeast of the present day Marathon Basin. Both the Martin Ranch and Housetop Mountain boulder beds are composed mainly of clast-bearing, matrix-supported mudstone which have pebbly sandstone, massive sandstone, and flysch beds interstratified with the mudstone and represent periodic deposition of debris flows, slumps, slides, and turbidites interspersed with normal basin deposition of flysch facies rocks. However, different clast types are found at the two localities. The Martin Ranch locality has clasts of Cambrian limestone and chert pebble conglomerate, the latter up to 90 m in length, that are absent at the other localities. Exotic Pennsylvanian limestone clasts and exotic Devonian metamorphic and volcanic rocks, common at Housetop Mountain, are rare or missing at Martin Ranch. The Clark Butte locality is unique because it lacks the mudstone which dominates the other two localities. Instead, the matrix is composed of a pebbly sandstone and conglomerate associated with thick sandstone beds. The boulder beds at this locality may represent upper fan channels and channel-lag deposits. The turbidites and olistostromes resulted from recycling of the southern edge of the tectonic basin as the advancing Ouachita thrusts uplifted the pre Haymond strata. Most of the clasts were from older basin formations exposed by these faults; however one of these thrusts also uplifted slivers of exotic Middle Cambrian limestone. Earthquakes probably triggered slumps and rock falls off the fault scarps. As the boulders travelled downslope plowing through the slope sediments, they accumulated more material. This combination of slide debris and slope mud turned the slumps and slides into debris flows. Between episodes of debris flows and turbidity currents, normal basin deposition of thinly bedded turbiditic sandstone and pelagic shale occurred. / text

Orientador: Giorgio Basilici / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-24T01:34:47Z (GMT). No. of bitstreams: 1 Luca_PedroHenriqueVieirade_D.pdf: 18777385 bytes, checksum: c055caccb8a267d7dde58a2477d6acb9 (MD5) Previous issue date: 2013 / Resumo: As formações Lagarto e Palmares (Cambriano-Ordoviciano, Domínio Estância) e a Formação Punta Negra (Devoniano, Precordilheira Argentina) representam unidades sedimentares antigas desenvolvidas em ambientes marinhos costeiros e plataformais dominados pela ação de ondas de tempestades. Nesta tese de Doutorado, estudaram-se depósitos de tempestade formados em uma área de intermaré (formações Lagarto e Palmares) e depósitos de tempestade desenvolvidos abaixo da linha de tempo bom em uma área de prodelta (Formação Punta Negra). As formações Lagarto e Palmares se desenvolveram em uma área de planície de maré aberta em que os processos sedimentares de maré e de tempestade interagiram entre si na distribuição de sedimentos de áreas costeiras até antepraia. Um detalhado estudo de análise de fácies foi utilizado para reconhecer e caracterizar as litofácies e os elementos arquiteturais, gerar um modelo de deposição para estas unidades e para discutir os fatores de geração e preservação das HCS em água rasa. Baseando-se na organização arquitetural dos depósitos sedimentares, construiu-se um modelo de distribuição de sedimento em que há uma passagem gradativa das áreas proximais de intermaré superior, dominadas por processos de maré e predomínio de sedimentos nas frações silte e argila, para as porções distais de intermaré inferior, em que prevalecem sedimentos arenosos e depósitos de tempestade. A Formação Punta Negra constitui uma espessa unidade sedimentar formada pela intercalação entre camadas areníticas e pelíticas. Por muitos anos esta unidade foi interpretada como um sistema deposicional marinho profundo produto de uma sedimentação gerada por fluxos turbidíticos. Contudo, neste trabalho esta unidade foi reinterpretada como um sistema deposicional de prodelta dominado pela atividade de ondas de tempestade. Uma análise de detalhe dos depósitos sedimentares permitiu identificar as principais fácies sedimentares, icnofácies e elementos arquiteturais e gerar um novo modelo de deposição para esta unidade. Construiu-se um modelo de sedimentação para esta unidade em que os depósitos se desenvolveram a partir da interação entre fluxos hiperpicnais gerados à frente de um sistema deltaico e fluxos oscilatórios de alta energia decorrentes de eventos de tempestade. Estes fluxos combinados possuíam direção perpendicular à paleolinha de costa, e perdiam energia no tempo e no espaço (costa afora). Os depósitos com maior granulometria, representados por areia média média-fina, são encontrados nas porções mais proximais e os sedimentos mais finos, representados por corpos pelíticos-arenosos, se concentram principalmente nas áreas distais do sistema deposicional / Abstract: Lagarto and Palmares formations (Ordovician-Cambrian, Estância Domain) and the Punta Negra Formation (Devonian, Argentine Precordillera) represent ancient sedimentary units developed in costal and platform storm dominated marine environments. In this PHD thesis, it was studied shallow water storm deposits developed in an intertidal area (Lagarto and Palmares formations) and storm deposits developed below the fair water wave base in an prodelta area (Punta Negra Formation). Lagarto and Palmares formations have been developed in an open coast tidal flat where the tidal and storm sedimentary processes have interacted to distribute sediments from the coast till the shoreface. Detailed facies analysis was used to recognize and characterize the lithofacies and architectural elements, define a depositional model e the controlling factors that preserved HCS in shallow-water. Based in the depositional architectural organisation, it was proposed a sedimentary distribution model in which there is a gradational transition between the proximal areas of upper intertidal, dominated by tidal processes and silty and shaly sediments, and the distal areas of lower intertidal, in which prevails sandy sediments and storm deposits. Punta Negra Formation constitutes a thick unit composed of monotonous interbeds of sandstone and sandy mudstone. This unit was previously interpreted as a deep water depositional system, however in this research it was reinterpreted as a storm dominated prodeltaic system. Detailed analysis of the sedimentary deposits allowed identifying the main sedimentary facies, ichnofacies and architectural elements and propose a new depositional model for this unit. It was built a sedimentary model in which the Punta Negra Formation deposits have been produced by combined and oscillatory flows which resulted by the combination of hyperpicnal flows and storm waves. The generated combined flows had a direction perpendicular to the paleocoast and were characterized by losing energy in the time and space (seawards). Coarser grained sediments, represented by medium size sand, are found in the proximal area and the finer grained sediments are mainly found in the most distal areas of the sedimentary system / Doutorado / Geologia e Recursos Naturais / Doutor em Ciências

Within the area under consideration there are two great series of strata. The lower one is known as the Purcell-Belt Series and is divided into two main groups. A widespread unconformity separates the Purcell Series from the younger and overlying Windermere Series. The Lower Purcell-Belt group consists of the Aldridge-Prichard, Creston-Ravalli, Kitchener-Wallace, and Siyeh-Striped Peak. They were deposited under marine conditions from the erosion of a western Precambrian Cascadia. The Upper Purcell-Belt group consists of the Dutch Creek, Mount Nelson and their equivalents in Canada and the Missoula Group of Montana and possibly the Priest River group of Washington. This group is separated from the Lower Purcell by a period of diastrophism marked by the intrusion of Purcell sills and the extrusion of Purcell lavas. The Upper Purcell-Belt sediments were derived from the positive areas as a result of the preceding crusted disturbance. The Purcell-Belt times were closed by large scale orogeny called the "Purcell Uplift". The north-south trending belt of Purcell mountains formed a landmass which greatly affected lower Palaeozoic stratigraphy. This positive area is commonly referred to as the "Montana Island". The Precambrian portion of the Windermere Series includes the Toby-Shedroof conglomerate, Irene Deola volcanics and the Horsethief Creek-Monk formations. The clastic formations were derived from the Purcell Mountains and deposited on their western flank. Marine conditions arose during Horsethief Creek times. The Cambrian portion of the Windermere Series was deposited in a north-south trending geosynclinal trough which extended from the Metaline quadrangle to the Field-Golden area of the Rocky Mountains and probably beyond. It includes the lower quartzitic Hamill Group and the overlying limy and argillaceous Lardeau group. They were deposited as the shoreline transgressed south and east over the "Montana Island" and reduced it from one of high relief to one of low relief. Stages of emergence and resumed sedimentation are indicated, by upper formations of the Lardeau group. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The Cambrian – Lower Ordovician Potsdam Group is a mostly siliciclastic unit that provides important insight into the paleoenvironmental, geologic and tectonic history of Early Paleozoic Laurentia. Nevertheless, in spite of 178 years of study the Potsdam in the Ottawa Embayment and Quebec Basin remains poorly understood. Also poorly understood is how the Potsdam relates with coeval strata regionally. In this work six siliciclastic paleoenvironments are recognized: (a) braided fluvial, (b) ephemeral fluvial, (c) aeolian, (d) coastal sabkha, (e) tide-dominated marine and (f) open-coast tidal flat. Fluvial strata were examined in particular detail and interpreted to consist of two end-member kinds. Braided fluvial deposits are dominated by low-relief bars formed in wide, shallow channels; however where basement structures limited the lateral growth of channels, flows were deeper and bar deposits thicker and higher angle. In contrast, ephemeral fluvial strata are dominated by sheetflood splay sedimentation with rare preservation of scour-filling supercritical bedform strata – all later subjected to aeolian reworking. In the upper Potsdam, alternating ephemeral and braided fluvial strata provide a record of climate change, which, respectively, correlate with documented global cool (arid) and warm (humid) periods during the Late Cambrian and Early Ordovician. Three allounits are recognized in Potsdam strata, recording regional episodes of sedimentation and facilitating correlation with coeval strata throughout eastern North America. These correlations, aided with provenance data from detrital zircons, show that changes in the areal distribution of sediment supply, accommodation and deposition/erosion were principally controlled by episodic reactivation of the Neoproterozoic Ottawa graben, which then periodically modified the stratigraphic expression of the ongoing Sauk transgression. Specifically, episodes of tectonic reactivation occurred during late Early to Middle Cambrian (allounit 1), late Middle to early Late Cambrian (allounits 2 – 3 unconformity), and Earliest Ordovician (allounits 3 – 4 unconformity). The earliest episode is correlated to regional extension of southern Laurentia, whereas the latter two are linked to peri-Laurentian accretion events that triggered reactivation of the Ottawa graben via the Missisquoi oceanic fracture zone.

The central Pelly Mountains in southeastern Yukon Territory consist of imbricate thrust sheets, which have undergone syn- and post-thrusting deformation and metamorphism. The local geology is further complicated by intrusion of Upper Cretaceous batholiths, and by strike-slip faulting related to the Tintina Fault, a major northwest-trending transcurrent fault of uppermost Cretaceous or early Tertiary age. This faulting disrupts the northeast edge of the study area. Upper Devonian and Mississippian strata are present in at least two of the thrust sheets, but the Mississippian volcanic rocks occur in only one of them. The volcanic rocks consist of volcaniclastic material with minor interbedded flows, and were deposited in a submarine environment. Several coeval and cogenetic syenite and trachyte domes and small stocks are the remains of vent areas. Although the volcanic rocks are all highly altered and show evidence of widespread chemical mobility, trace element data indicate that the rocks are meta-luminous trachytes, most closely resembling peralkaline volcanics generated in extensional environments. This suggestion of a predominantly extensional tectonic setting in mid-Mississippian time in the Pelly Mountains is consistent with recent tectonic syntheses for the area. Stratabound and stratiform massive base metal sulphide deposits that occur within the Mississippian volcanic sequence are similar in many respects to the Kuroko-type volcanogenic massive sulphide deposits of Japan. The Pelly Mountains deposits, however, are among the first known occurrences in the world of Kuroko-type mineralization in a rift environment. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate