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Lower Cretaceous (Barremian to Albian) fossil plant assemblages are preserved in sediments of the Otway Group, Otway Basin, and contemporaneous Strzelecki Group, Gippsland Basin, southeastern Australia. Detailed lithofacies and biofacies analyses of terrestrial strata within the upper Eumeralla Formation (Albian), Otway Group, allow fine-scale interpretation of braided fluvial and paludal depositional environments throughout the succession. The previously described flora is re-assessed in light of changes in depositional style and plant communities to describe six Albian biofacies. Forests in the highlands are dominated by Araucariaceae conifers, which turn over to Podocarpaceae and Cheirolepidiaceae forests on the dry, raised areas in the lowlands. Ferns and angiosperms inhabit the moist floodplains and water ferns and lycophytes dwell in the ox-bow lakes. Significant changes occur between floral communities characteristic of riparian, levee and floodbasin settings through the Early Cretaceous. Albian floras are characterized by the dominance of broad-leafed araucarian conifers, an understory of diverse ferns and a dearth of seedferns and angiosperms. There is a notable absence of macrofossil ginkgoaleans in the Eumeralla Formation, although they reappear in younger (Turonian) deposits in southeastern Australia, but angiosperms are extremely scarce as macrofossils compared to the diversity recently recorded in the pollen record. Abundant charcoal demonstrates that fire continued to be a significant environmental factor at high latitudes during the middle to late Albian. The discovery of dinoflagellate species supports an earlier marine incursion and increased coastal environments, probably inhabited by cheirolepids, across the Otway Basin. Palaeontological, palynological and sedimentological data has provided a synthesis of the region's warm, high-latitude, palaeoclimatic setting in the Albian stage of the Early Cretaceous when compared to the cooler Barremian to Aptian.

International audience; Recent field and analytical work have considerably improved our understanding of the structure of the MullerRange along the frontal trend of the Papuan Fold and Thrust Belt (PFTB) in western Papua New Guinea (PNG).However numerous questions remain unresolved concerning the geological evolution of the region. In particular,the Late Cretaceous to Oligocene history of the region is largely unknown due to the absence of a continuousstratigraphic record. Here, we use both new and existing low-temperature thermochronology data to investigatethe geological history of the Muller Range. Thermal history models based on these data suggest two majorCenozoic cooling episodes. The youngest, and best constrained, is clearly recorded in the stratigraphic recordand relates to Neogene collision at the northern margin of the Australian continent. An older episode of comparableor greater magnitude occurred in the Eocene to Oligocene and may relate to the removal of1500–3000m of Late Cretaceous to Eocene section across the Muller Range prior to the widespread deposition ofthe shelfal Darai Limestone. We suggest that extension along major faults beneath the Muller Range accommodatedsedimentation from the Late Cretaceous to the Eocene, consistent with long-lived extensional structuresobserved in neighbouring regions. In contrast to the Muller Range area, an almost continuous Late Cretaceous toEocene stratigraphic sequence is preserved in the hinterland

This study provides the first record of the high diversity and abundance of Victoria's earliest angiosperms from outcrops in the non-marine upper Eumeralla Formation of the Otway Basin. The biostratigraphic schemes established for the Albian of Australia are re-evaluated using more reliable and widespread index species, resulting in the construction of a high-resolution Albian biostratigraphy in the Otway Basin. New localities in the uppermost outcrop of the Eumerella Formation contain spore–pollen assemblages that cannot be placed in the existing scheme and a new Upper Phimopollenites pannosus Subzone is recognised. The correlation of the P. pannosus Zone to the geochronological timescale was re-assessed and shows that it is 103–101.51 Ma, giving a late Albian age. In contrast to previous studies that record low diversity angiosperm assemblages in the Albian, this study identifies twenty-three angiosperm species, including one new species, Tricolpites tortuous. The high diversity and abundance of angiosperm pollen in the Otway Basin provides further evidence that angiosperms probably migrated into eastern Gondwana via South America and Antarctica.

Detailed “Quaternary-style” quantitative spore–pollen counts, with a pollen sum based on total non-angiosperm seed plants, from a southern high palaeolatitude (60–65°) terrestrial sequence in Gippsland, southeast Australia has revealed strong vegetation and climate variability during the Albian. This variability is more pronounced than previously suggested in global Early Cretaceous vegetation and climate reconstructions. The quantitative spore–pollen record shows drying throughout the Albian based on upward decreasing total ferns and variation in podocarp and total Alisporites/Vitreisporites pollen. This record suggests that although global climate during the Albian is considered to have been warm, stable and equable, regional factors such as water availability and continentality were the main drivers of this vegetation change.

The Holocene and pre-Holocene sediments and stratigraphy of the Yarra Delta have been examined using nearly 600 geotechnical bores. The oldest Holocene unit is the Coode Island Silt that has two depocentres, each up to 20.0–25.0 m thick, separated by a NW–SE belt of older pre-Holocene units. The northern depocentre represents estuarine infill to the Yarra and Maribyrnong, a river system, whereas the southern depocentre appears to be an offshore bay facies. The youngest unit is the Port Melbourne Sand, which is largely restricted to the area south of the present Yarra River. It is between 5.0 and 28.0 m thick, and is diachronous with the underlying Coode Island Silt. New 14C shell dates from the Coode Island Silt and Port Melbourne Sand have shown an age range between 8341 and 2760 yrs BP. These sediments infill former swamplands covering low-stand river valleys of the Yarra and Maribyrnong rivers across West Melbourne, Fishermans Bend and South Melbourne. After ca 2760 yrs BP active sedimentation in the delta ceased as base-levels fell, and Yarra and Maribyrnong river sediments bypassed the delta because of falling bay levels. The Yarra and Maribyrnong river courses also shifted progressively westwards behind growing beach barriers of the Port Melbourne Sand. A comparable stratigraphy exists between the Yarra Delta and the adjacent Port Phillip Bay, i.e. marine and lagoonal shelly sediments of the Coode Island Silt and barrier sands of the Port Melbourne Sand infill last-glacial channels cut into the middle Pleistocene Fishermans Bend Silt.

The initial stage of continental extension between Australia and Antarctica was associated with lateral changes in extension direction along the margin that reflects the three-dimensional nature of strain during continental rifting. In the Cretaceous Otway Basin, this change in extension direction was related to substantial rheological differences in the lithosphere across the boundary between two Paleozoic fold belts, the Lachlan and Delamerian, with the net extension direction at a high angle to this boundary. The initial Early Cretaceous rifting preserved within the onshore Otway Basin has two main structural subdomains in the eastern and western Otway Basins distinguished by different structural trends of Early Cretaceous normal faulting. This is not controlled by a variation in preexisting structural weaknesses within the underlying Paleozoic basement because the same geometry of extensional structures also occurs within the basement to the north irrespective of the preexisting structural grain. The eastern Otway Basin is dominated by NE-striking NW-dipping normal faults. In the western Otway Basin, the faults define arrays of predominantly NE-dipping or SW-dipping faults separated by wide accommodation zones defined by folding and variably striking and dipping faults. The partitioning of strain along the boundary between the eastern and western Otway Basins is accommodated by a progressive change in strike of faults and not via a transfer fault. Younger rifting in the Late Cretaceous had a similar extension direction in the western Otway basin, but had a dominant seaward dip, extension appears to have been hindered in the eastern Otway basin by a Proterozoic/Paleozoic basement feature. These factors produced a region of diverging extension along the lithospheric boundary between the Delamerian and Lachlan Fold Belts that lead to failure along this boundary and the formation of a localized sinistral trans-tensional graben, the Shipwreck trough, in the early Late Cretaceous. As a result, the younger rifting stepped south of the eastern Otway Basin leaving Bass Strait (the strait between the Australian mainland and Tasmania) a failed rift. The formation of oceanic crust in the Mid to Late Eocene followed the boundary of Late Cretaceous rifting, which led to the formation of the Tasman Fracture Zone.

VandenBerg (2010) has written a very well-supported account of the Eocene–Oligocene paleovalleys and basalts of the southern margins of the Eastern Uplands in Gippsland. He is probably quite correc...

Southern Australian breakup history is divisible into three phases. The first phase began with Callovian (c.159–165 Ma) rifting in the western Bight Basin. During the Tithonian (c.142–146 Ma), rifting extended eastwards into the Duntroon, Otway and Gippsland Basins. By the Valanginian (c.130–135 Ma), ocean crust formed between India and western Australia. Structural style in the western Bight changed to thermal subsidence. However, fluvio-lacustrine rift sedimentation continued in Duntroon, Otway and Gippsland until the Barremian (c.115–123 Ma) when these basins also changed to thermal subsidence. The diachronous progression of basin fill types produces a progressive shift in ages of potential source, seal and reservoir intervals along the margin.The second phase began during the Cenomanian (c.92–97.5 Ma) with uplift in eastern Australia, stress reorganisation and divergence of basin development. The Otway, Sorell and Great South Basins formed in a transtensional regime. These tectonics resulted in trap generation through faulting, inversion and wrenching. During the Santonian, oceanic spreading began in the southern Tasman Sea (c.85 Ma). Slow extension caused thinning of continental crust in the Bight and Otway Basins and subsidence into deeper water. Ocean crust formed south of the Bight Basin in the Early Campanian (c.83 Ma) and also started extending up the eastern Australian coast.The third stage in development was caused by Eocene changes to fast spreading in the Southern Ocean (c.44 Ma), final separation of Australia and Antarctica, and cessation of Tasman Sea spreading. These events caused collapse of continental margins and widespread marine transgression. The resultant loading, maturation and marine seal deposition are critical to petroleum prospectivity in the Gippsland Basin.