摘要:

A taxonomically diverse plant microfossil assemblage recovered from a fully cored, marine, glacigene sequence of the Grant Formation, Canning Basin, Western Australia, contains 68 palynomorph species derived mostly from ferns, lycopods, gymnosperms and algae. The assemblage has been assigned to the newly definedGranulatisporites confluensOppel-zone.G. confluenswas first described from Late Palaeozoic sequences of the Chaco-Parana Basin, Argentina, and together with other key species indicates close correlation with assemblages from South America, India, Africa and, to a lesser extent, Antarctica.

ISSN:0812-0099    

DOI:10.1080/14400958808527936

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Blueschist facies metabasites from the Emo Metamorphics of Papua New Guinea contain the assemblage quartz-albite-phengite-stilpnomelane-ferroglaucophane-chlorite-almandine-epidote-sphene-apatite + relict igneous pyroxene with omphacitic rims. The assemblage is similar to the lawsonite-epidote transition zone on New Caledonia. Textural variation from unfoliated to foliated blueschist is marked by an increase in retrograde modal actinolite and chlorite, suggesting that strain has accelerated the actinolite- and chlorite-forming reaction. Application of standard geobarometers and geothermometers to the primary assemblage suggests pressure and temperature conditions of metamorphism of approximately 7.0 kbar and 320°C. The textural variation suggests that the Emo Metamorphics may be a sliver of oceanic crust caught up in the thrusting that accompanied obduction of the Papuan ophiolite. The resulting depressurization led to retrograde growth of actinolite and chlorite.

ISSN:0812-0099    

DOI:10.1080/14400958808527937

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The sequence formerly mapped as Spero Bay Group (Lower Devonian) and containing the palaeontologically significant Point Hibbs Formation includes Lower Devonian, Ordovician and possibly Cambrian rocks. The Point Hibbs Formation (Lower Devonian) is redefined to include interbedded fossiliferous lime packstone and fossiliferous claystone, characterized by large coral heads. Gordon Group limestone contains a conodont and brachiopod fauna indicating a late Middle Ordovician age and includes fenestral-peloidal and oncolitic lithologies typical of the Gordon Group elsewhere in Tasmania. Strata of different ages are juxtaposed along east-dipping thrust planes. Differences in conodont colour alteration indices suggest a minimum relative vertical displacement of 2 km between the Point Hibbs Formation and the Gordon Group. High-level thrusting and westward transport direction may have been a general feature of Middle-Late Devonian deformation in western Tasmania.

ISSN:0812-0099    

DOI:10.1080/14400958808527938

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The Gippsland Basin in southeastern Australia contains Early Cretaceous sandstone and shale of the Strzelecki Group, which are overlain by Late Cretaceous to Early Tertiary sandstone, shale and coal of the Latrobe Group. Around the basin flanks, the groups are separated by a marked angular unconformity dated in previous publications at about 100 Ma. Evidence from seismic sections together with dipmeter logs and palynological reports on samples from offshore petroleum exploration wells indicates that the unconformity developed during deposition of the Latrobe Group and is dated at about 76 Ma (within theNothofagidites senectusspore-pollen zone). The unconformity is probably a breakup unconformity marking initiation of the opening of the adjoining Tasman Sea.

ISSN:0812-0099    

DOI:10.1080/14400958808527939

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The Westmoreland Conglomerate is the oldest formation of the Middle Proterozoic Tawallah Group, the basal group of the McArthur Basin sequence. It unconformably overlies Early Proterozoic granite, acid volcanics and metamorphics, and comprises up to 1800 m of coarse, immature sandstone and conglomerate. The Westmoreland Conglomerate is divided into five fining-upward sequences deposited in a braided river/alluvial fan environment. The main source of sediments was located in the northeast; the sediment-bearing rivers originated in the rising highlands of the northward extension of the Mt Isa Orogen. Their course was controlled by two east-trending palaeohighs, separated by about 20 km of lowlands. The southern high is represented by the Murphy Inlier and the northern high by a belt of east-trending gravity lows interpreted as granitic basement.

ISSN:0812-0099    

DOI:10.1080/14400958808527940

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The Devonian Narraburra Granite in southern New South Wales is located on the western margin of the Bogan Gate Synclinorium in the Temora Rift and is associated with other post- or late orogenic sodic granites and tholeiitic and transitional basic intrusive rocks. This region represents the rifted boundary between the Wagga-Omeo and Kosciusko Terranes. The granite is peralkaline (Al2O3/Na2O + K2O = 0.95–0.96), contains aegirine and arfvedsonite, and is only the third occurrence of peralkaline granite recorded in the Lachlan Fold Belt of southeastern Australia.

ISSN:0812-0099    

DOI:10.1080/14400958808527941

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The Early Devonian Yackandandah Granite in northeast Victoria was emplaced along the western boundary of the Omeo Metamorphic Complex. Deformation of probable mid-Devonian age resulted in the formation of a ductile shear zone in the granite, termed the Kiewa shear zone. Displacement of granite boundaries and shear-zone fabrics, including excellently developed S-C fabrics, indicate that the shear zone accommodated ∼7 km of sinistral strike-slip displacement, with no evidence for thrusting as suggested in previous studies. Detailed mapping of fabrics across the shear zone suggest that ∼ 70% of strain was accommodated by the formation of the finite strain foliation (S-planes), with the remaining strain accommodated by discrete slip along C-planes parallel to the shear-zone boundary.

ISSN:0812-0099    

DOI:10.1080/14400958808527942

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The Early Cainozoic geological history of the Gazelle Peninsula, east New Britain, Papua New Guinea, indicates that extensional tectonics have influenced sedimentation and volcanism in this part of the New Britain arc-trench complex since the earliest Miocene. Remapping of the Gazelle Peninsula has resulted in a significant revision of the Mio-Pliocene stratigraphy and structure: three new formations (Pali River Conglomerate, Bergberg Formation and Arabam Diorite) and six new structural units (Baining Mountain Horst and Graben Zone, Wide Bay Fault System, Nengmutka Caldera, Keravat Caldera, Sikut Caldera, and Warangoi Trend) are defined. Three formations (Yalam Limestone, Nengmutka Volcanics and Sinewit Formation) are redefined. The first obvious influence of the Baining Mountain Horstand Graben Zone, which runs centrally through the Gazelle Peninsiula, postdates an orogenic event at the Oligocene-Miocene boundary. By the mid-Miocene, emergent caldera centres were localized along this extensional zone, and the products of the volcanic centres, the Nengmutka Volcanics, were distributed over a 600 km2elongate area.

ISSN:0812-0099    

DOI:10.1080/14400958808527943

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The Ben Bullen plutons constitute a small medium-K gabbro-tonalite-trondhjemite suite spatially and temporally associated with extensive adamellite and granite of the Bathurst Batholith. The mafic composition of the bulk of the Ben Bullen rocks suggests a mantles source for the parent magma. Chemical and petrographic studies indicate that the rocks are closely comparable with medium-K calc-alkaline volcanic suites in island arcs. The Ben Bullen series are M-type granites in the sense of being formed by crystal fractionation of a gabbroic parental magma. Initial crystallization and separation of olivine and pyroxene followed by marked fractionation of hornblende probably drove the differentiating magma along a typical calc-alkaline trend of strong alkali-enrichment. It is possible that the rise of these mantle-derived melts into the crust initiated the crustal melting that produced the associated felsic K-rich granitoids of the Bathurst Batholith.

ISSN:0812-0099    

DOI:10.1080/14400958808527944

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The main Permian coal-bearing basins of eastern Australia are the foreland Sydney and Bowen Basins in the east and the interconnected cratonic Cooper and Galilee Basins in the west. The morphotectonic domains of these basins are described in terms of sediment thicknesses, sediment accumulation rates, percentage of coal and coal accumulation rates. Early Permian deposition in the foreland basins was marine, with coal measures restricted to the orogenic and cratonic margins. Because of expansion of the eastern orogen, marine deposition was replaced in the Late Permian by deltaic then fluvial sediments and extensive coal measures. The cratonic basins were sites of coal measure deposition for most of the Permian.

ISSN:0812-0099    

DOI:10.1080/14400958808527945

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor