A MIDDLE JURASSIC FOSSIL FOREST FROM NEW ZEALAND

Palaeontology ◽  
2005 ◽  
Vol 48 (5) ◽  
pp. 1021-1039 ◽  
Author(s):  
VANESSA THORN
Keyword(s):  
New Zealand ◽  
Middle Jurassic ◽  
Fossil Forest

What we know (and what we don't) about the petroleum prospectivity of the Northland Basin, North Island, New Zealand

2009 ◽  
Vol 49 (1) ◽  
pp. 383 ◽  
Author(s):  
Chris Uruski
Keyword(s):  
New Zealand ◽  
Early Cretaceous ◽  
Late Cretaceous ◽  
Middle Jurassic ◽  
Source Rocks ◽  
The West ◽  
Eastern Margin ◽  
Gondwana Margin ◽  
Jurassic Coal ◽  
Coal Measures

The offshore Northland Basin is a major sedimentary accumulation lying to the west of the Northland Peninsula of New Zealand. It merges with the Taranaki Basin in the south and its deeper units are separated from Deepwater Taranaki by a buried extension of the West Norfolk Ridge. Sedimentary thicknesses increase to the northwest and the Northland Basin may extend into Reinga. Its total area is at least 65,000 km2 and if the Reinga Basin is included, it may be up to 100,000 km2. As in Taranaki, petroleum systems of the Northland Basin were thought to include Cretaceous to Recent sedimentary rocks. Waka Nui–1 was drilled in 1999 and penetrated no Cretaceous sediments, but instead drilled unmetamorphosed Middle Jurassic coal measures. Economic basement may be older meta-sediments of the Murihiku Supergroup. Thick successions onlap the dipping Jurassic unit and a representative Cretaceous succession is likely to be present in the basin. Potential source rocks known to be present include the Middle Jurassic coal measures of Waka Nui–1 and the Waipawa Formation black shale. Inferred source rocks include Late Jurassic coaly rocks of the Huriwai Beds, the Early Cretaceous Taniwha Formation coaly sediments, possible Late Cretaceous coaly units and lean but thick Late Cretaceous and Paleogene marine shales. Below the voluminous Miocene volcanoes of the Northland arc, the eastern margin of the basin is dominated by a sedimentary wedge that thickens to more than two seconds two-way travel time (TWT), or at least 3,000 m, at its eastern margin and appears to have been thrust to the southwest. This is interpreted to be a Mesozoic equivalent of the Taranaki Fault, a back-thrust to subduction along the Gondwana Margin. The ages of sedimentary units in the wedge are unknown but are thought to include a basal Jurassic succession, which dips generally to the east and is truncated by an erosional unconformity. A southwestwards-prograding succession overlies the unconformity and its top surface forms a paleoslope onlapped by sediments of Late Cretaceous to Neogene ages. The upper succession in the wedge may be of Early Cretaceous age—perhaps the equivalent of the Taniwha Formation or the basal succession in Waimamaku–2. The main part of the basin was rifted to form a series of horst and graben features. The age of initial rifting is poorly constrained, but the structural trend is northwest–southeast or parallel to the Early Cretaceous rifting of Deepwater Taranaki and with the Mesozoic Gondwana margin. Thick successions overlie source units which are likely to be buried deeply enough to expel oil and gas, and more than 70 slicks have been identified on satellite SAR data suggesting an active petroleum system. Numerous structural and stratigraphic traps are present and the potential of the Northland Basin is thought to be high.

The first find of Eurycephalitinae (Jurassic Ammonitina) in New Zealand and its biogeographic implications

1991 ◽  
Vol 65 (4) ◽  
pp. 689-693 ◽  
Author(s):  
Gerd E. G. Westermann ◽  
Neville Hudson
Keyword(s):  
New Species ◽  
New Zealand ◽  
Papua New Guinea ◽  
Middle Jurassic ◽  
New Guinea ◽  
Time Correlation ◽  
Eastern Pacific ◽  
East Pacific ◽  
Single Fragment ◽  
Overlap Area

Uppermost temaikan strata from southwest Auckland Province, North Island, New Zealand, have recently yielded a small fauna of Middle Jurassic ammonites previously believed to be endemic to the eastern Pacific borderlands, although a single fragment of the new species described below was previously reported in a large Tethyan assemblage from Papua, New Guinea, by Westermann and Callomon (1988). The New Zealand assemblage consists of the dimorphic pair Xenocephalites (♂) and Lilloettia (♀) with close morphologic ties to species from the latest Bathonian Steinmanni Standard Zone of the Andean Province (Riccardi et al., 1989). This new find permits direct time-correlation of the uppermost part of the Temaikan Stage (Marwick, 1951, 1953) with the East-Pacific latest Bathonian Steinmanni Zone and with the East-Tethyan Late Bathonian Macrocephalites apertus Association. The upper Temaikan Stage of south Otago Province, southeastern South Island, New Zealand, has also yielded rare representatives of the Tethyan Macrocephalitinae, so that the New Zealand area in the late Middle Jurassic was in the overlap area of Tethyan and East-Pacific Subrealms.

scholarly journals The Geology of Basement Rocks in the Southeastern Tararua Range, North Island, New Zealand

2021 ◽  
Author(s):  
◽  
Lisa Ann Foley
Keyword(s):  
New Zealand ◽  
Early Cretaceous ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Depositional Environment ◽  
Active Continental Margin ◽  
Turbidity Currents ◽  
High Angle ◽  
Basement Rocks ◽  
Geochemical Analyses

<p>Basement rocks within the southeastern Tararua Range belong to two associations: a sedimentary association (greywacke, argillite, calcareous siltstone, conglomerate and olistostrome) and a volcanogenic association (metabasite, chert, red argillite and limestone). Rocks of the sedimentary association are more abundant and have been deposited by turbidity currents and debris flows in a deep water, marine environment. Three turbidite and two intercalated non-turbidite lithofacies are recognized. Sedimentological data suggest that the sediment was deposited in a submarine fan system (mid-fan environment), probably in a trench. The alternating greywacke-argillite beds have detrital compositions which are essentially quartzo-feldspathic. Framework mode and geochemical analyses indicate that the sediment was derived from an active continental margin that was shedding detritus of mainly acid-volcanic and metamorphic origin. Rocks of the volcanogenic association, although volumetrically minor, are widely distributed. Geochemical analyses of metabasites suggest that they were erupted in an oceanic environment, both at a mid-ocean ridge and an intra-plate setting. The presence of radiolaria skeletons in red argillite and chert indicates a hemiplagic depositional environment for these rocks. Rocks of the volcanogenic association often have conformable contacts. These rocks have a related depositional environment and represent seafloor material. Where observed, contacts between rocks of the two associations are always faulted. Deformation in the field area is characterized by development of the following types of structures: several generations of folds, faults at both a low angle and high angle to bedding, shear foliation and melange. The region has undergone the following deformational events, outlined from oldest to youngest: 1) folding with at least two fold generations present. 2) fragmentation and disruption of the beds by faults. Low-angle to bedding faults and high-angle to bedding faults have disrupted the bedding. Where these structures have occurred to a great extent, a chaotically disrupted unit, melange, has formed. 3) post-melange folding. 4) recent faulting related to the present strike-slip regime in New Zealand. Rocks have undergone prehnite-pumpellyite facies metamorphism. The rock types, their field relationships and the deformation that the area has undergone is consistent with accretion at a convergent plate margin. Radiolaria were extracted from two red chert samples. In the study the radiolaria define a Middle Jurassic age, which indicates that the sediments in the southeastern Tararua Range must be of Middle Jurassic in age or younger (possibly Cretaceous). A similar sample from the Manawatu Gorge to the north of the study area contained radiolaria of Late Jurassic-Early Cretaceous age. Sediments in both areas therefore belong to fossil zone 5 (Late Jurassic-Early Cretaceous) of MacKinnon (1983).</p>

scholarly journals Sedimentology and depositional environments of Murihiku Supergroup sediments exposed in the Southland Syncline, New Zealand: Implications for reservoir potential in the Great South Basin

2021 ◽  
Author(s):  
◽  
Angus David Howden
Keyword(s):  
New Zealand ◽  
Middle Jurassic ◽  
Petroleum Industry ◽  
Depositional Environments ◽  
Seismic Facies ◽  
Late Triassic ◽  
Petrographic Composition ◽  
South Basin ◽  
Porosity And Permeability ◽  
Reservoir Potential

<p>A considerable amount is known about the biostratigraphy and organic geochemistry of the Murihiku Supergroup sediments exposed in coastal outcrops of the Southland Syncline, New Zealand. Much less work has been undertaken on the sedimentology of these strata, or understanding their depositional environments and depositional trends through time. What these implications are for reservoir prospectivity in the adjacent Great South Basin, has also had little study focused on it.  This thesis addresses these issues by undertaking outcrop-based sedimentological and facies interpretations of these rocks, thin-section based petrographic composition and provenance analysis, augmented by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM), as well as porosity and permeability measurements from outcrop core plugs. Petroleum industry seismic data has additionally enabled seismic facies mapping of Murihiku rocks in the offshore Great South Basin.  Outcrop observations point to a progressive change in depositional setting, from shelf / upper slope settings during the Late Triassic, to base of slope turbidite deposition in the Early Jurassic. This transgression is followed by regression into fluvial settings in the youngest outcropping Murihiku rocks in the study of Middle Jurassic age. Petrographically the sandstones are feldspathic and lithic arenites and feldspathic and lithic wackes. Provenance suggests derivation from an evolving, intermediate arc that was becoming more siliceous through Late Triassic and Middle Jurassic time. Diagenesis is characterised by early calcite and chlorite precipitation which have almost completely destroyed any primary porosity. Any secondary micro porosity has subsequently been infilled through dissolution of framework grains and zeolitization. SEM and core plug porosity and permeability measurements corroborate the diagenetic changes observed petrographically, with only fluvial facies of Middle Jurassic (Upper Temaikan) age showing any measureable porosity or permeability.  As a result, reservoir potential for the Late Triassic to Middle Jurassic, Murihiku Supergroup rocks analysed in this study is low. Younger Murihiku sandstones which are postulated to occur offshore in the Great South Basin are likely to be less influenced by burial diagenesis. As shown from North Island occurrences, these younger successions hold some potential.The reservoir potential for these youngest portions of the Murihiku succession therefore remains positive, both in the Great South Basin, as well as other frontier areas of Zealandia, and continue to provide an exploration target for the petroleum industry.</p>

Sign in / Sign up

Export Citation Format

Share Document