Geomorphic constraints on the Late Neogene tectonics of the Otway Range, Victoria
Titel:
Geomorphic constraints on the Late Neogene tectonics of the Otway Range, Victoria
Auteur:
Sandiford, M.
Verschenen in:
Australian journal of earth sciences
Paginering:
Jaargang 50 (2003) nr. 1 pagina's 69-80
Jaar:
2003-02
Inhoud:
A Pliocene strandline system in the Hanson Plain Sands, between the volcanic plains of the Western District and the northern flanks of the Otway Range in southwest Victoria, provides an excellent datum against which to measure Late Neogene fault-related uplift. Individual strandlines that can be traced from elevations of ∼120 m near Cobden to ∼245 m on the Ferguson Hill structure are displaced across northeast-trending faults and monoclines associated with the Simpson and Ferguson Hill structures. A break in slope in the Otway Range front at elevations of 230-280 m, beneath which drainage incision parallels the trends of the strandlines, probably correlates with the Pliocene coastline on the ancestral Otway Range. By analogy with correlative systems in the Murray Basin, deposition occurred during sea-stands between 0 and 65 m above present-day sea-level, implying uplift of between 175 and 240 m since the Early Pliocene. Enhanced incision parallel to the strandlines, in combination with tilting of fault blocks about northeast axes at a high angle to the strandlines, has facilitated the development of a remarkable rectilinear drainage net. Local inversion of the drainage where it focused basalt flows constrains the age of incision and faulting to greater than ca 1 Ma and, most probably, less than ca 2 Ma.
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