ISSN:0197-9337    

DOI:10.1002/esp.3290170402

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

ISSN:0197-9337    

DOI:10.1002/esp.3290170403

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe main features of the Australian physical landscape are of the order of 107‐108years old. This contradicts the widely held view that little of the Earth's topography predates the Quaternary and that erosion cycles are carried to planation within tens of millions of years. Much of the Australian landscape must have developed over similar timescales to that of the tectonic evolution of the continent itself. The study of the geomorphology of such ancient terrains may therefore be seriously deficient unless it is considered within the context of continental‐scale tectonic development. Application of this approach shows that there are strong links between the geomorphology of Australia and plate movements, ocean spreading, plate convergence, tectonostratigraphic terranes, orogenesis and epeirogenesis.The most important factor contributing to the survival of ancient landscapes in Australia is the low rate of denudation which the continent has experienced during the Mesozoic and Cenozoic. This is largely a consequence of orogenic stability, although the absence of significant Quaternary glaciation may also be of importance. However, in order for landforms to have survived over such timespans, denudation must not only have been low, but must also have been highly localized over space and time. This has been the case both on a regional scale, with long‐term denudation rates of 0‐2 m Ma−1in central Australia contrasting with higher rates along the continental margins, and on a local scale, with denudation confined to valleys, leaving divides and interfluves almost

ISSN:0197-9337    

DOI:10.1002/esp.3290170404

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA range of evidence from the Lachlan valley in the southeast Australian highlands is consistent with Neogene isostatic rebound in response to denudational unloading. This evidence is found along the inland edge of the highlands in the transition zone between the highlands proper and the Lachlan's inland alluviated valley and the intracratonic Murray Basin. The amounts and rates of uplift indicated by offsets of suballuvium bedrock profiles and the long profiles of Tertiary valley‐filling basalts are consistent with modelling of denudational rebound using known rates of highland denudation and basinal sedimentation, and reasonable crustal properties. The modelling shows that weak to moderately strong strong lithosphere (effective elastic thickness,Te= 1‐25 km) and strong lithosphere (Te= 100 km) are all consistent with the observed amounts of rebound. Strong lithosphere must be broken, however, to be consistent with the field data. Even in the Australian setting, which is characterized by very low rates of denudation, isostatic rebound in response to denudational unloading must be a significant factor in maintaining highland elevation and must be incorporated in models of long‐term landscape evolution. It would be expected that denudational isostatic rebound would be an even more significant component of long‐term landscape evolution in areas of higher denudatio

ISSN:0197-9337    

DOI:10.1002/esp.3290170405

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe long‐term evolution of streams in the Shoalhaven catchment of southeast New South Wales has been a contentious issue for decades. Several authors have suggested that the Shoalhaven River was captured at the sharp eastward bend near Tallong: this has been used as evidence for the westward migration of the east Australian divide in this area. Other workers, however, have argued that capture did not occur and that the location of the divide has been stable throughout the Tertiary. A vast sheet of sediments which spread across and infill a palaeovalley network cut into a broad undulating plain in the middle Shoalhaven catchment provides a record of stream behaviour since at least the start of the Tertiary. This record shows that the Shoalhaven River and many of its tributaries have maintained almost the same courses since at least the very Early Tertiary. This provides strong evidence against the capture hypothesis. The record further suggests that during the Paleogene these streams were graded to a level within the southeast Australian highlands; their depths of incision thus cannot be used as evidence for the extent of uplift of the southeast Australian highlands during this tim

ISSN:0197-9337    

DOI:10.1002/esp.3290170406

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractLandscape evolution in northern New England is characterized by the persistence of landforms over long time periods. The topography in the study area was initiated by Paleozoic diapiric intrusion of granitic rocks as highs within metasedimentary and volcanic rocks. This framework was probably reinforced by differences in the resistance of the massive igneous and the fractured metasedimentary rocks to erosion. As a result, both the Tertiary and present‐day relief of the area consists of uplands developed on granitic rocks partly overlain by Paleozoic volcanic rocks, and lowlands developed on Paleozoic metasediments. Extensive volcanism in the Tertiary had only a minimal effect on this relationship. A significant impact of Tertiary volcanism, however, was the diversion of major streams across topographic highs. Despite 19‐35 Ma of incision, these streams are still far from establishing equilibrium profiles and dissecting the highs.The persistence of topography for a timescale of the same order of magnitude as that conventionally thought to be required for planation is due to reduced denudation rates in a passive tectonic setting and the presence of erosion‐resistant Paleozoic igneous units. The latter influence is indicated by knickpoint persistence for 19‐35 Ma on streams diverted across these rocks. Since it is generally considered that such disequilibria are short‐lived features formed by Quaternary or ongoing deformation, this knickpoint persistence has important implications for landscape analyses that use disequilibria to assess recent tectonism in a

ISSN:0197-9337    

DOI:10.1002/esp.3290170407

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe Clarence River on Australia's east coast has an anomalous drainage pattern. Its right‐bank tributaries are markedly barbed, suggesting reversal, whereas Tertiary volcanism has disrupted its left‐bank drainage. The southeast‐flowing Clarence is closely aligned with the northwest‐flowing Condamine River just across the Continental Divide. The Condamine‐Clarence alignment is continued by a large southern tributary, the Orara River, which flows northwest, away from the sea, to meet the southeast‐flowing Clarence. A broad river with a quite different character flows east from near the Orara‐Clarence junction to the sea. This is essentially an overflow channel.This series of aligned streams, the Condamine‐Clarence‐Orara, represents the remains of an earlier northwest‐flowing stream that extended the full length of the Clarence‐Moreton Basin, an eastern extension of the Great Artesian Basin. During the Jurassic, the Clarence‐Moreton Basin was filled with sediments from the surrounding highlands, including those to the east of the present coastline. Continental rifting from Late Cretaceous times onwards led to the opening of the Tasman Sea, causing the reversal and beheading of the original northwest‐flowing streams and the formation of the Great Escarpment.The evolution of the Clarence River does not fit into most conventional geomorphic paradigms such as cycles, climatic geomorphology or steady‐state landforms. It is the result of a succession of unique events on a very long timescale, and as such is a classic example of

ISSN:0197-9337    

DOI:10.1002/esp.3290170408

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe Great Escarpment of the eastern Cape York Peninsula of far northeast Australia consists of two parallel, offset segments. In the hinterland of Cooktown, these segments are separated by the Mesozoic Laura Basin. To the west of the Basin, the Great Escarpment appears to have evolved on a tiltblock associated with Cenozoic normal faulting along the Palmerville Structure, a major north‐south tectonic feature forming the western margin of the Basin. To the east of the Basin, the Great Escarpment appears to have developed along a north‐northwest axis of upwarping. The existence of this axis is supported by evidence of drainage capture, by the association between the axis and Quaternary volcanism and by fracture patterns in the Mesozoic sandstones along the line of the axis. The eastern segment of the Escarpment appears to be younger than the western. This model supports an earlier hypothesis of escarpment formation in the region as a result ofen echelondouble lines of upl

ISSN:0197-9337    

DOI:10.1002/esp.3290170409

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe West Victorian Uplands is a region of low relief, gentle gradients, young volcanicity and local domal uplift. These characteristics distinguish it from the rest of the Eastern Highlands of Australia. The origin of the West Victorian Uplands dates back to uplift in the Cretaceous, but elevation and relief have always remained low. Further uplift, extending westwards from central Victoria, may have begun raising the West Victorian Uplands in Middle Tertiary times. Doming, fault activity, earthquakes and volcanism are extending progressively westwards. Not only may the Eastern Highlands of Victoria have grown in this way in the past, but the area may also provide a view of the early evolution of the Eastern Highlands of Australia.

ISSN:0197-9337    

DOI:10.1002/esp.3290170410

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe denudation chronologies of five uplands of contrasting geological structure located at the eastern margin of the Australian Craton are examined. They are the Isa Highlands, MacDonnell Ranges and Flinders Ranges (fold mountains, orogenic setting); the Arcoona Plateau (dissected plateau, platform setting); and the Gawler Ranges (massif of old silicic volcanics, cratonic setting). In each, surfaces of Mesozoic age, many of them exhumed and of pre‐Cretaceous age, are preserved. Each also appears to have been uplifted recurrently. Each was either overwhelmed or bordered by the Early Cretaceous (Neocomian‐Aptian) sea.Tectonism associated with the break‐up of Gondwana probably allowed this important marine transgression. Thereafter, thalassostatic and erosional/depositional isostatic responses have maintained the uplands as uplands and the intervening basins as negative topographic and structural units; the pattern of topography has been constant for the last 60

ISSN:0197-9337    

DOI:10.1002/esp.3290170411

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY