The tertiary rocks of the snowy mountains, Eastern Australia
Titel:
The tertiary rocks of the snowy mountains, Eastern Australia
Auteur:
Gill, Edmund D. Sharp, K. R.
Verschenen in:
Australian journal of earth sciences
Paginering:
Jaargang 4 (1956) nr. 1 pagina's 21-40
Jaar:
1956
Inhoud:
Streams on an ancient peneplain (probably Cretaceous) were rejuvenated, and excavated youthful valleys. Gold was included in the thin, generally coarse, poorly-sorted sediments of these streams. Further tectonic movements stopped erosion in thalwegs and instituted regional accumulation of lacustrine sediments which extended far beyond the old stream channels. Continued movements resulted in three or more cycles of sedimentation over a wide area on what is now the Kiandra Tableland, each beginning with a sandy phase and ending with a lignite phase. In places, the succession is intercalated with flows of olivine basalt. The present residuals are remnants of extensive lava fields which concluded the cyclic sedimentation, and have preserved the sediments. The sediments and lavas cross the present Divide, and must precede its formation. The lacustrine sediments are shown by their fossil flora to be early Tertiary, possibly Upper Eocene or Lower Oligocene. On present knowledge they are older than the Yallourn brown coal of Victoria, and comparable in age with the Wensleydale brown coal. The climate was pluvial and warm, with a rich flora. Elevation may have continued throughout the Tertiary, with maxima associated with the times of extrusion of the Older Basalts of the Lower Cainozoic and the Newer Basalts of the Upper Cainozoic. The building of the Snowy Mountains took much longer than visualized in Andrews' Kosciusko Epoch hypothesis.
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