THE PETROLEUM GEOLOGY OF THE ONSHORE BONAPARTE BASIN

1981 ◽  
Vol 21 (1) ◽  
pp. 5
Author(s):  
R. Laws

The Bonaparte Basin formed in the Early-Mid Palaeozoic as a result of divergent left-lateral wrenching within the northeast trending Halls Creek Mobile Zone. The main phase of deposition in the onshore portion of the basin occurred in the Late Devonian to Early Carboniferous, when over 5 000 m of sediments were laid down. Extensive outcrops around the basin margins demonstrate complex facies relationships and the continuance of wrench faulting during deposition.A reef complex of Late Devonian age fringes the western basin margin. In the basin centre, shales and silts of the Bonaparte Beds form the lateral equivalent of the various facies cropping out around the flanks.A northeast trending basement high occurs in the eastern Bonaparte Basin. A barrier reef complex is predicted to cap the ridge with subtidal and estuarine sediments deposited in the shallow water conditions that existed east of the barrier.Oil shows have been encountered in shallow core holes drilled around the basin margins. Source rock analyses have also highlighted the potential of the basinal shales and lagoonal carbonates to produce hydrocarbons. Gas has flowed on test from thin sandstones within the Bonaparte Beds in two of the wells drilled onshore.Reservoirs are predicted to be present in sandstones of the Bonaparte Beds and also where secondary porosity is developed in carbonates, especially those of the reef complex.Although subsurface structural data are sparse, anticlines are mapped from outcrop data and structures related to both faulting and compaction over basement highs are predicted to occur.

2012 ◽  
Vol 43 (2) ◽  
pp. 161-169 ◽  
Author(s):  
André Nel ◽  
Jan-Michael Ilger ◽  
Carsten Brauckmann ◽  
Jakub Prokop

Bechala sommeriIlger & Brauckmann, 2012, the type species of the type genus of the early Late Carboniferous (Namurian) family Bechalidae Ilger & Brauckmann, 2012, is redescribed. It does not belong to the order Megasecoptera as previously proposed. The taxon is clearly attributable to Odonatoptera for the typical venation characters as CuA separating from MP obliquely, a true arculus with concave RP and convex MA emerging from a composite vein R+MA, short ScP, and presence of convex intercalaries IR2 and IR1 between the main branches of RP3/4, RP2 and RP1. We transfer this taxon with the monospecific family Bechalidae to Odonatoptera. A new diagnosis is given for Bechalidae and its type genus Bechala. Furthermore, the presence of an oblique subnodal crossvein very far from the ending of ScP and close to the base of RP2 confirms the hypothesis that the subnodus is a structure originally independent of the nodus with a different function in relation to wing tracheation. The Bechalidae are included in a clade (Meganeuridae–Sinierasipteridae–Bechalidae–Lapeyridae–Nodialata), in contrast to a sister group relationships between the two clades Meganisoptera (=Namurotypidae–Paralogidae–Kargalotypidae–Kohlwaldiidae–Meganeuridae) and Odonatoclada (=Lapeyridae–Nodialata), while the potential relationships between the Campylopteridae and the Lapeyridae and Nodialata are rejected. Bechala represents a ‘damselfly-like’ ecological niche in the Namurian, showing the high diversity of the earliest known Odonatoptera, strongly suggesting an Early Carboniferous, if not Late Devonian age for this pterygote clade.


1988 ◽  
Vol 25 (9) ◽  
pp. 1349-1364 ◽  
Author(s):  
D. C. McGregor ◽  
S. R. McCutcheon

The predominantly volcanic Piskahegan Group has commonly been considered Early Carboniferous, based on its stratigraphic position. However, spores recently discovered in the Carrow Formation, an alluvial fan deposit in the exocaldera facies, indicate that most, if not all, of the group is of Late Devonian (late Famennian) age. The spore assemblage includes several species reported previously from Ireland, Belgium, and eastern Europe, some of them apparently restricted to the southern parts of the Old Red Sandstone Continent in Late Devonian time. Comparison of records of earliest occurrences suggests that the incoming of some species was diachronous. Volcanic rocks of the Piskahegan Group are coeval with post-Acadian, tin–tungsten-bearing granites elsewhere in New Brunswick and are considered the surface expression of plutonism that resulted from Acadian continental collison.


1999 ◽  
Vol 90 (2) ◽  
pp. 127-146 ◽  
Author(s):  
P. Aleksandrowski ◽  
R. Kryza ◽  
S. Mazur ◽  
C. Pin ◽  
J. A. Zalasiewicz

AbstractThe Polish Sudetes on the NE margin of the Bohemian Massif comprise a complex mosaic of pre-Permian basement units, traditionally included in the Variscides. A hypothesis of significant Caledonian orogenesis in this area originated in the 1920s, was subsequently rejected, and then was recently revived in models which invoked Early Palaeozoic to Early-Mid Devonian subduction and continental collision along a proposed extension of the Tornquist suture zone. We reassess the evidence invoked in support of the Caledonian orogeny, such as supposed regional pre-Upper Devonian unconformity, Ordovician bimodal magmatism and radiometric, palaeontological, palaeomagnetic and structural data, and suggest these are either inconclusive or misinterpreted. On the other hand, the Sudetes record Mid?-Late Devonian blueschist metamorphism followed by an Early Carboniferous regional high temperature event, widespread Late Devonian/Early Carboniferous flysch/molasse sedimentation and abundant granite intrusion in the Carboniferous to Early Permian. We discuss the usage of the term ‘Caledonian’ in a plate tectonic context and suggest it should not be used simply to denote Early to Mid-Palaeozoic tectonic activity. The tectonic evolution of the Sudetes was temporally different from, and resulted from convergence of different crustal domains than that of the British-Scandinavian-Pomeranian Caledonides. The Sudetic Palaeozoic sequences most probably developed on Armorican Neoproterozoic crust and in adjacent oceanic(?) domains and, therefore, the Sudetes form part of the Variscan orogenic belt.


2002 ◽  
Vol 76 (2) ◽  
pp. 229-238
Author(s):  
Zhong-Qiang Chen ◽  
Neil W. Archbold

Two new genera of the Chonostrophiidae are proposed herein to accommodate the resupinate shells from the Famennian sediments of the Late Devonian in the Santanghu Basin of the Balikun area, Xinjiang Province, northwestern China. Santanghuia santanghuensis new genus and species is distinguishable from other chonostrophiids by the possession of a pair of long dorsal anderidia and absence of a dorsal median septum. Balikunochonetes liaoi new genus and species is distinct because of the presence of a pair of anderidia with secondary anderidia, and a dorsal median septum. Santanghuia new genus is considered to be phylogenetically related to Chonostrophia of late Early to Middle Devonian age, while Balikunochonetes has possibly given rise to Chonostrophiella of Early Devonian age and is a likely ancestor of Tulcumbella of Early Carboniferous age.


Author(s):  
Alexander J.P. Houben ◽  
Geert-Jan Vis

Abstract Knowledge of the stratigraphic development of pre-Carboniferous strata in the subsurface of the Netherlands is very limited, leaving the lithostratigraphic nomenclature for this time interval informal. In two wells from the southwestern Netherlands, Silurian strata have repeatedly been reported, suggesting that these are the oldest ever recovered in the Netherlands. The hypothesised presence of Silurian-aged strata has not been tested by biostratigraphic analysis. A similar lack of biostratigraphic control applies to the overlying Devonian succession. We present the results of a palynological study of core material from wells KTG-01 and S05-01. Relatively low-diversity and poorly preserved miospore associations were recorded. These, nonetheless, provide new insights into the regional stratigraphic development of the pre-Carboniferous of the SW Netherlands. The lower two cores from well KTG-01 are of a late Silurian (Ludlow–Pridoli Epoch) to earliest Devonian (Lochkovian) age, confirming that these are the oldest sedimentary strata ever recovered in the Netherlands. The results from the upper cored section from the pre-Carboniferous succession in well KTG-01 and the cored sections from the pre-Carboniferous succession in well S05-01 are more ambiguous. This inferred Devonian succession is, in the current informal lithostratigraphy of the Netherlands, assigned to the Banjaard group and its subordinate Bollen Claystone formation, of presumed Frasnian (i.e. early Late Devonian) age. Age-indicative Middle to Late Devonian palynomorphs were, however, not recorded, and the overall character of the poorly preserved palynological associations in wells KTG-01 and S05-01 may also suggest an Early Devonian age. In terms of lithofacies, however, the cores in well S05-01 can be correlated to the upper Frasnian – lower Famennian Falisolle Formation in the Campine Basin in Belgium. Hence, it remains plausible that an unconformity separates Silurian to Lower Devonian strata from Upper Devonian (Frasnian–Famennian) strata in the SW Netherlands. In general, the abundance of miospore associations points to the presence of a vegetated hinterland and a relatively proximal yet relatively deep marine setting during late Silurian and Early Devonian times. This differs markedly from the open marine depositional settings reported from the Brabant Massif area to the south in present-day Belgium, suggesting a sediment source to the north. The episodic presence of reworked (marine) acritarchs of Ordovician age suggests the influx of sedimentary material from uplifted elements on the present-day Brabant Massif to the south, possibly in relation to the activation of a Brabant Arch system.


2001 ◽  
Vol 75 (6) ◽  
pp. 1202-1213 ◽  
Author(s):  
Robert L. Carroll

The origin of tetrapods from sarcopterygian fish in the Late Devonian is one of the best known major transitions in the history of vertebrates. Unfortunately, extensive gaps in the fossil record of the Lower Carboniferous and Triassic make it very difficult to establish the nature of relationships among Paleozoic tetrapods, or their specific affinities with modern amphibians. The major lineages of Paleozoic labyrinthodonts and lepospondyls are not adequately known until after a 20–30 m.y. gap in the Early Carboniferous fossil record, by which time they were highly divergent in anatomy, ways of life, and patterns of development. An even wider temporal and morphological gap separates modern amphibians from any plausible Permo-Carboniferous ancestors. The oldest known caecilian shows numerous synapomorphies with the lepospondyl microsaur Rhynchonkos. Adult anatomy and patterns of development in frogs and salamanders support their origin from different families of dissorophoid labyrinthodonts. The ancestry of amniotes apparently lies among very early anthracosaurs.


Author(s):  
V. A. Stepanov ◽  

Information on the geological and isotopic age of the Kubaka gold-silver deposit in the Omolon middle massif in the North-East of Russia is presented. It has been established that the Kubaka deposit geological age lies in between the Late Devonian age of the Kedon series volcanites, containing the gold-silver mineralization, and the Early Carboniferous age of the Korbinsky suite terrigenous rocks, overlapping the volcanites and the mineralization. The post-ore nature of the Omolon complex dykes, which produce no significant impact on the distribution of gold mineralization in ore bodies, is shown. According to isotope dating, the following stages of the Kubaka deposit formation are distinguished: the accumulation of the Kubaka suite tuffs (369 Ma); the introduction of subvolcanic intrusions (344 and 337 Ma); the formation of ore metasomatites (335±5 Ma); the formation of gold-silver mineralization (330 and 334 - 324 Ma); the introduction of post-ore dikes (179±8 - 176±10 Ma).


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