COMPRESSIONAL GROWTH OF THE MINERVA ANTICLINE, OTWAY BASIN, SOUTHEAST AUSTRALIA—EVIDENCE OF OBLIQUE RIFTING

Shipwreck Trough, east-central Otway Basin, evolved through Early Cretaceous to Santonian extension, followed by Campanian–Paleocene and Miocene to Recent pulses of compression.Onshore to offshore correlation of seismic sequences combined with 3D seismic mapping reveals that the Minerva anticline is located above an Early Cretaceous, northeast trending, basement-involved, graben. The graben-forming, northeast and north–south trending faults became largely inactive prior to the end of the Early Cretaceous. During the Turonian to Santonian, the northeast trending Point Ronald anticline and newly formed east–west trending normal faults controlled sediment distribution. The structural style changed in the Campanian as the northeast trending Minerva anticline began to form with a coeval, northwest-trending, axial-perpendicular fault array located along the crest of the fold. The location and orientation of this fault set is consistent with a compressional mechanism for fold growth. Similar compressional folding events during the Miocene–Recent modified and tightened the fold. Isopach maps show that during the Campanian to Maastrichtian, sediment thinned onto the nascent Minerva anticline, but accommodation rate outpaced structural growth, preserving a continuous sedimentary sequence.The timing of compressional fold growth is enigmatic. Campanian–Maastrichtian compression at the Minerva anticline was synchronous with over 10 km of extension accommodated by the Tartwaup–Mussel hingeline, 50 km to the south. Although the compression may be far-field effects associated with Tasman Basin sea floor spreading, we speculate that the Minerva anticline grew by transpression within a larger left-lateral transtensional Shipwreck Trough.

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Post mid-Cretaceous inversion tectonics in the Danish Central Graben – regionally synchronous tectonic events?

Bulletin of the Geological Society of Denmark ◽

10.37570/bgsd-2003-49-11 ◽

2002 ◽

Vol 49 ◽

pp. 129-144

Author(s):

Ole Valdemar Vejbæk

Keyword(s):

Stress Field ◽

Eastern Alps ◽

Upper Jurassic ◽

Normal Faults ◽

Sea Floor ◽

Early Oligocene ◽

Tectonic Events ◽

Structural Style ◽

Reverse Faulting ◽

Sea Floor Spreading

Structural analysis of the Upper Cretaceous to Palaeogene succession in the Danish Central Graben suggests continuous inversion heralded in the Late Hauterivian and continuing into Palaeogene times. The following phases of increased intensity are identified: 1) latest Santonian, 2) Mid Campanian, 3) late Maastrichtian, 4) Late Paleocene – Eocene, and 5) Early Oligocene. Phases 1 through 3 are Sub-Hercynian, phase 4 is Laramide, and phase 5 is Pyrenean according to Alpine Orogen nomenclature. A temporal change in structural style is noted from early inversion confined to narrow zones associated with reverse faulting along pre-existing normal faults to late inversion dominated by gentle basinwide flexuring and folding. Inversion phases in the Danish Central Graben seem to be synchronous with inversion phases along the Sorgenfrei-Tornquist Zone. The location of inversion is generally spatially linked to Upper Jurassic – Lower Cretaceous depocentres, whereas older depocentres generally have remained intact. The origin of the compressional stress field is generally based on suggested compressional stresses transmitted into the foreland from the Alpine Orogen. In the Sub-Hercynian phase, orogenic compression dominated the Eastern Alps and Northern Carpathians to produce a likely NW oriented compression. However, structures in Denmark rather suggest a transpressional environment resulting from NNE–SSW compression. Furthermore, transmission of Alpine orogenic stresses into the foreland commenced in the Turonian, a considerable time after the Late Hauterivian and later inversion precursors. Ridge-push forces transmitted from sea-floor spreading south of the Charlie-Gibbs fracture zone, particularly from the Goban Spur SW of Ireland, acting in conjunction with Alpine orogenic stresses are suggested as the cause for the stress field.

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GEOLOGIC HISTORY OF THE BASS BASIN

The APPEA Journal ◽

10.1071/aj73006 ◽

1974 ◽

Vol 14 (1) ◽

pp. 45 ◽

Cited By ~ 2

Author(s):

V. A. Robinson

Keyword(s):

Early Cretaceous ◽

Middle Eocene ◽

Central Area ◽

Structural Features ◽

Northern Coast ◽

Geologic History ◽

Lower Tertiary ◽

Structural Style ◽

Late Tertiary ◽

Structural Growth

The Bass Basin is located offshore between the southern coast of Victoria and the northern coast of Tasmania. It is bounded on the west by King Island and on the east by Flinders Island and the Bassian Rise. Water depths throughout the basin rarely exceed 270 feet (82 metres) and the area has been actively explored for hydrocarbons since 1963.The oldest sedimentary rocks encountered whilst drilling are Early Cretaceous, but the greatest volume of sediment was deposited during the Tertiary. Lithologies vary from continental sandstone, siltstone, shale, and coal in the older, non-marine Cretaceous to Middle Eocene section to limestone, marl, mudstone, and shale in the younger, marine Late Eocene to Recent section. Drilling and seismic data indicate that there was a considerable amount of volcanic activity in the Bass Basin throughout its history.Three distinctively different structural provinces can be recognised in the basin. These provinces are referred to as- a) southeastern area, b) central area, and c) northwestern area.The southeastern area exhibits the earliest structural growth (Early Cretaceous) whereas the structural growth in the central and northwestern areas occurred in Early and Late Tertiary respectively. Structural style also varies from tilted fault blocks with thousands of feet of vertical displacement in the southeastern area, to low relief, small anticlinal folds and minor faults in the northwestern area. Most of the prominent structural trends are oriented in a northwest-southeast direction which is parallel or sub-parallel to the present basin axis.Seismic and E-log correlations within the non-marine Cretaceous and Lower Tertiary section are extremely difficult and palynology is used to differentiate time-rock units. Five separate zones are identifiable within the Eocene and Paleocene, and the Cretaceous has been sub-divided into ten zones which can be related to the time-rock units in the adjacent Otway and Gippsland Basins.Non-commercial accumulations of hydrocarbons have been found in three different structural features: Pelican, Cormorant and Bass −3. These accumulations are from within the Lower Tertiary non-marine sequence known as the Eastern View Group.

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Cretaceous

Geological Society London Memoirs ◽

10.1144/gsl.mem.1992.013.01.13 ◽

1992 ◽

Vol 13 (1) ◽

pp. 131-139 ◽

Cited By ~ 6

Author(s):

J. M. Hancock ◽

P. F. Rawson

Keyword(s):

Early Cretaceous ◽

Sedimentary Basins ◽

Major Change ◽

The Arctic ◽

Sea Floor ◽

The North ◽

Marine Sedimentation ◽

History Of ◽

Sea Floor Spreading ◽

Sea Area

AbstractEarly CretaceousThe Cretaceous Period lasted for about 70 million years. During this time there was a major change in the sedimentary history of the area as tectonism died down and deposition started of an extensive blanket of coccolith ooze: the Chalk. The change took place mainly over a brief interval across the Albian/Cenomanian (Lower/Upper Cretaceous) boundary, at about 95 Ma. Until that time crustal extension along the Arctic-North Atlantic megarifts continued to influence the tectonic evolution of northwest Europe (Ziegler 1982, 1988). This tensional régime caused rifting and block faulting, particularly across the Jurassic-Cretaceous boundary (Late Cimmerian movements) and in the mid Aptian (Austrian phase). During the latter phase, sea-floor spreading commenced in the Biscay and central Rockall Rifts. The northern part of the Rockall Rift began to widen too, possibly by crustal stretching rather than sea-floor spreading (Ziegler 1988, p. 75). During the Albian the regional pattern began to change and by the beginning of the Cenomanian rifting had effectively ceased away from the Rockall/Faeroe area.Most of the Jurassic sedimentary basins continued as depositional areas during the Early Cretaceous, but the more extensive preservation of Lower Cretaceous sediments provides firmer constraints on some of the geographical reconstructions. The marked sea-level fall across the Jurassic-Cretaceous boundary isolated the more southerly basins as areas of non-marine sedimentation, and it was not until the beginning of the Aptian that they became substantially marine.The extent of emergence of highs in the North Sea area is difficult to assess, especially where

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