Includes bibliographies. / 4 v. : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Depts. of Geology & Geophysics and Botany, 1997?

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Studies of large herbivorous mammal (ungulate) communities have revealed an association between increased tooth crown height (hypsodonty) and a shift to more arid environments over the Cenozoic. Ecometric analyses have also been used to examine the relationship between current climate conditions and crown height of these communities, and very successfully used to estimate past precipitation. Small herbivorous mammals (rodents and lagomorphs) have been shown to similarly adapt to changing habitats over the Cenozoic, but did so millions of years earlier than larger mammals. Here, we have utilized ecometric methods to examine the relationships between rodent and lagomorph crown height and diversity with current climate conditions, finding strong correlations of community structure parameters with climate, particularly mean annual temperature, maximum temperature of the warmest month, and minimum temperature of the coldest month. We applied the resultant regression equations to well-sampled fossil localities from North America, spanning over 37 million years, allowing estimation of climate conditions in deep time. As expected, estimates show a general pattern of decrease in both precipitation and temperature across North America from 37 Ma to the present. Overall, these findings provide a new broadly-applicable proxy for estimation of Cenozoic climate conditions at a local scale.

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Large discrepancies remain regarding the timing of Cenozoic paleoclimatic and paleoenvironmental transitions in the central Asia. The first order driving force behind these changes has been intensively debated. Global climate change, the uplift of Tibetan Plateau, and the evolution of Paratethys sea have been proposed as three major candidates. To understand the evolutionary history of climate and environment of the region and controlling factors responsible for these paleoclimatic and paleoenvironmental changes, a combined study utilizing multiple proxies, including microfossils, bulk carbonate carbon and oxygen isotopes, long chain alkenones, plant n-alkane-based indices (carbon preference index, average chain length and Paq) and compound-specific carbon and hydrogen isotopes of higher plant n-alkanes, was carried out on a long, continuous and well-dated section in Dahonggou, Qaidam Basin, northern Tibetan Plateau. A parallel study was also carried out in another relatively shorter section in the Xunhua Basin, northern Tibetan Plateau. Six intervals of paleoclimatic and paleoenvironmental transitions over an interval of ~35 Myr can be recognized in the studied sections, including Late Eocene-Early Oligocene gradual drying (prior to ~30 Ma), Middle Oligocene aridification (~30-26 Ma), Late Oligocene-Early Miocene wetting (~26-21 Ma), Early Miocene drying (~21-17 Ma), Middle Miocene climatic optimum (~17-13 Ma), and deteriorated climate since the late Middle Miocene (~13 Ma onwards). The reconstructed onsite C4 plant abundance including occurrence of C4 plants and their thriving and the followed decreasing, a sensitive indicator of available moisture level in the environment, agrees well with these intervals. Microfossils and long-chain alkenones suggest that a relic sea existed in the Qaidam Basin during the Middle Miocene, thus falsifying any hypothesis of significant variations in elevations of northern Tibetan Plateau prior to the Middle Miocene. The relatively stable elevations since the Eocene and before the Middle Miocene of, respectively, the central-southern part and northern part of the Plateau reveals an insignificant role of Tibetan Plateau uplift in controlling the evolution of central Asian climate and environment during the early Cenozoic. However, the Middle Miocene marine transgression and the rapid plateau-scale uplift since the late Middle Miocene probably contributed to the Middle Miocene climatic optimum and the initiated aridification afterwards in the central Asia. A comparison of proxy records in the northern Tibetan Plateau with the global benthic oxygen isotope record suggests a tight relation between the climatic/environmental transitions in the central Asia and global climatic changes. This lends support to the hypothesis that global climate, by controlling the moisture supply to the continental interior, played the dominant role in the evolution of climate and environment of central Asia during the Cenozoic time. / published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

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El área estudiada comprende las regiones de Igualada, Manresa, Vic y Girona, desde la Conca de Barberà hasta la playa de Pals, en el Mediterráneo. De las subclases Paleotaxodonta y Pteriomorphia se han reconocido un total de 14 familias, 27 géneros (44 especies y 10 indeterminables específicamente). De ellas, 20 especies se citan por primera vez en esta área y 3 especies son endémicas. Frente a otros bivalvos, presentan casi siempre la concha.Las especies se hallan predominantemente en litologías detríticas finas y calcáreas. En su mayoría eran epifaúnicas y semiinfaúnicas. De las pocas infaúnicas, su modo de fijación era diverso. Predominantemente, habitaban la parte alta de la zona infralitoral, entre la marea baja y los 50 m de profundidad. Aguas con salinidad normal. Los géneros habitan actualmente en latitudes tropicales o templadas.En cuanto a la edad de las unidades que las contienen, la asociación de especies indica que es dificil discernir una edad luteciense o bartoniense, si bien las unidades inferiores contienen mayor número de especies lutecienses y las unidades superiores, especies bartonienses. La mayoría de los géneros tienen representantes actuales.La asociación de especies de dichas unidades inferiores muestra gran similitud con las del Luteciense de las cuencas del W europeo. La de las superiores con el Bartoniense de Aquitania y Biarritz. Ambas, con las del Priaboniense de Italia y Balcanes. / The area studied includes the regions of Igualada, Manresa, Vic and Girona, from the Conca de Barberà zone to the Pals beach, on the Mediterranean coast.14 families and 27 genera (44 species and 10 of undeterminable species) of the subclasses Paleotaxodonta and Pteriomorphia (bivalves) have been recognised. 20 of those species have been reported for the first time in this area and another 3 are endemic. Unlike other bivalves, the great majority of them keep the shell.The species are predominantly found in fine, calcareous detrital lithologies. Most of the species were epifaunal or semi-infaunal. The few infaunal species present in the area had diverse fixation systems. For the most part, they dwelled in the upper part of the infralittoral zone, between the low tide and 50 m deep, in waters of normal salinity. The genus dwell in tropical or temperate latitudes.As for the age of the units that contain them, the association of species shows that it is difficult to discern Lutetian or Bartonian age; although the presence of Lutetian species is higher in lower units, and the Bartonian species appear in a larger number in upper units. Most of the genuses have representation nowadays.The association of species found in the lower units shows a great similarity to those of the Lutetian of the west European basins. The one found in the upper units, bears resemblance to the Bartonian of Aquitanie and Biarritz. Both associations show similarities to those found in the Italian and Balkan Priabonian.

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Late Cainozoic environmental changes in Kashmir (33°30' to 34°30' N: 74°10' to 75°30' E) have been reconstructed using a range of techniques. The sedimentary record in Kashmir consists of a thick (>1000m) basin-fill sequence known as the Karewa group, together with glacial and related sediments in the surrounding mountain flanks. The Karewa sediments are fluviolacustrine in origin and comprise alternations of conglomerates, sands and clayey silts. Work on the lower Karewa formation, which has previously been dated palaeomagnetically to between 4 and 0.4 MaBP, involved the semi- quantitative analysis of clay-mineral assemblages by X-ray diffraction.The clay minerals in the lower Karewa mudstones are interpreted as detrital clays which reflect weathering within Kashmir basin. The analyses showed a change in clay mineralogy between about 2.5 and 2.3MaBP, from abundant kaolinite to abundant smectite. Work on the upper Karewa formation involved field description and mapping of facies, sedimentological analysis, dating using thermoluminescence (TL) and amino-acid racemization, and analysis of ostracod assemblages from lacustrine sediments. Areal restriction of the lake in Kashmir occurred about 0.4MaBP with the rapid uplift of the Pir Panjal Range. Sedimentological data show that aeolian dust formed a major input into the lake. Ostracod assemblages show that the lake itself was cool, shallow, alkaline and had abundant plant macrophytes, The lake drained between 120 and SOkaBP. Stratigraphical, sedimentological and faunal evidence suggests that this was a result of tectonically-induced drainage rather than climatically-induced desiccation. The glacial history of the surrounding mountain flanks was reconstructed by field mapping of glacial sediments and dated using TL and radiocarbon methods. Present and past patterns of glaciation wore assessed by the determination of equilibrium-line altitudes (ELAs), glaciation thresholds (GTs) and cirque aJtitudes. Glaciers extended to 2150 m a.s.l in the Great Himalayan flank and 2600 m a.s.l. in the Pir Panjal. There is evidence for only 2 pre-Holucene advances in Kashmir, the older of which predates 35kaBP. Present patterns of glacierization indicate a SW to NE rise in the height of ELAs and GTs suggesting topographic and precipitation control. An apparent reversal of trends during the past is explained by Quaternary uplift of the Pir Panjal Range.