UPLIFT AND EROSION ON THE ASHMORE PLATFORM, NORTH WEST SHELF: CONFLICTING EVIDENCE FROM MATURATION INDICATORS.

1995 ◽  
Vol 35 (1) ◽  
pp. 333
Author(s):  
G.R. Beardsmore ◽  
P.B. O'Sullivan
Keyword(s):  
Vitrinite Reflectance ◽  
Temperature Drop ◽  
Late Triassic ◽  
Maximum Temperature ◽  
North West ◽  
The North ◽  
Conflicting Evidence ◽  
Uplift And Erosion ◽  
Two Populations ◽  
Track Analysis

The Ashmore Platform is situated to the north of the Browse Basin, on the North West Shelf, off the coast of Western Australia. Apatite fission track analysis (AFTA™), vitrinite reflectance and fluo­rescence alteration of multiple macerals (FAMM) measurements were undertaken on drill cuttings material recovered from the Late Triassic sequence of the oil exploration well, Ashmore Reef-1.Vitrinite reflectance measurements indicate that the Late Triassic sequence is currently experienc­ing maximum temperature. However, reflectance methods were suspected of being unreliable due to suppression of the reflectance, a common problem when dealing with marine influenced sediments. The FAMM technique was used to provide an alter­native maturity estimate using the same speci­mens. The FAMM results suggested that vitrinite reflectance is suppressed and that the true matu­rity is higher than conventional reflectance mea­surements predict.The results also suggest that some of the cuttings material from the sampled level is contaminated by material from higher in the Late Triassic sequence. Both the AFTA™ and FAMM data show bi-modal populations from some depths. It was possible to distinguish between the two populations and esti­mate the maturity of the caved material. FAMM and AFTA™ results together imply that maximum palaeotemperature was reached in the Mid-Creta­ceous, corresponding to a major unconformity in the well.The FAMM results do not agree with published maturity estimates based on conodont alteration indices (CAI), which suggest that temperatures have only recently and rapidly reached current levels. The AFTA™ results can also be interpreted to support this model. Furthermore, sonic velocity data in Miocene limestone suggests post-Miocene erosion, which would be expected to be associated with a temperature drop.

Prospectivity insights from automated pre-interpretation processing of open-file 3D seismic data: characterising the Late Triassic Mungaroo Formation of the Carnarvon Basin, North West Shelf of Australia

2015 ◽  
Vol 55 (1) ◽  
pp. 15 ◽  
Author(s):  
Cliff C. Ford ◽  
James K. Dirstein ◽  
Alistair John Stanley
Keyword(s):  
Spatial Databases ◽  
Late Triassic ◽  
Data Sets ◽  
3D Seismic ◽  
Gas Reservoirs ◽  
Waveform Data ◽  
Open File ◽  
North West ◽  
The North ◽  
Carnarvon Basin

Waveform data from pre-interpretation processing is used in nine Late Triassic interpretation case studies from an area extending more than 30,000 km2 across the Exmouth Plateau, Kangaroo Trough and Rankin Trend on the North West Shelf of Australia. Events selected from a database of automatically generated surfaces extracted from six large open-file 3D marine surveys (~16,000 km2) are used to analyse reservoirs, seals, and pore fluid within the Brigadier and Mungaroo formations in this peer-reviewed paper. Today, geoscience teams are challenged with vast data sets such as the archived versions of more than 125 Carnarvon Basin 3D seismic surveys. Pre-interpretation processing delivers a database of numerous seismic events that cannot be effectively managed using traditional interpretation workstations. With, however, a 3D viewer to query, edit and merge the results, geoscience teams are able to review many large surveys and the surfaces in their interpretation workflows. At the 2013 WABS Conference in Perth, WA, two papers offered models for the Late Triassic gas reservoirs. These models represent many years of synthesis and integration of data by teams of geoscientists from two of the major operators on the North West Shelf. Validation and corroboration of the proposed models was gained by using selected pre-interpretation surfaces. Stacking patterns, waveform fitness, amplitude and two-way time surfaces from these spatial databases revealed geological insights about the formations, such as their complexity of structure, extent of reservoirs, and continuity of seals, along with a better understanding about the trapping and charge systems of the fields.

Evaluation of trends in extreme temperatures simulated by HighResMIP models across Europe

2020 ◽  
Author(s):  
Gerard van der Schrier ◽  
Antonello Squintu ◽  
Else van den Besselaar ◽  
Eveline van der Linden ◽  
Enrico Scoccimarro ◽  
...  
Keyword(s):  
High Resolution ◽  
Western Europe ◽  
Extreme Values ◽  
Maximum Temperature ◽  
Western Balkans ◽  
North West ◽  
The Balkans ◽  
The North ◽  
Summer Maximum ◽  
Maximum Temperatures

<p>The comparison of simulated climate with observed daily values allows to assess their reliability and the soundness of their projections on the climate of the future. Frequency and amplitude of extreme events are fundamental aspects that climate simulations need to reproduce. In this work six models developed within the High Resolution Model Intercomparison Project are compared over Europe with the homogenized version of the observational E-OBS gridded dataset. This is done by comparing averages, extremes and trends of the simulated summer maximum temperature and winter minimum temperatures with the observed ones.</p><p>Extreme values have been analyzed making use of indices based on the exceedances of percentile-based thresholds. Winter minimum temperatures are generally underestimated by models in their averages (down to -4 deg. C of difference over Italy and Norway) while simulated trends in averages and extreme values are found to be too warm on western Europe and too cold on eastern Europe (e.g. up to a difference of -4% per decade on the number of Cold Nights over Spain). On the other hand the models tend to underestimate summer maximum temperatures averages in Northern Europe and overestimate them in the Mediterranean areas (up to +5 deg. C over the Balkans). The simulated trends are too warm on the North West part and too cold on the South East part of Europe (down to -3%/dec. on the number of Warm Days over Italy and Western Balkans).</p><p>These results corroborate the findings of previous studies about the underestimation of the warming trends of summer temperatures in Southern Europe, where these are more intense and have more impacts.  A comparison of the high resolution models  with the corresponding version in CMIP5 has been performed comparing the absolute biases of extreme values trends. This has shown a slight improvement for the simulation of winter minimum temperatures, while no signs of significant progresses have been found for summer maximum temperatures.</p>

scholarly journals Siwalik basin of Arunachal Himalaya, India: a case study

1998 ◽  
Vol 18 ◽  
Author(s):  
P. K. Das ◽  
H. Baruah
Keyword(s):  
Sedimentary Facies ◽  
Western Himalaya ◽  
Large River ◽  
Ocean Basin ◽  
North West ◽  
The North ◽  
Late Neogene ◽  
Main Boundary Fault ◽  
Uplift And Erosion ◽  
Arunachal Himalaya

The Siwalik basin of Arunachal Himalaya is a part of the Himalayan foreland. Due to continental collision between Indian and Eurasian plates, the Himalayan mountain system experienced intense uplift and erosion and as a result, a large amount of siliciclastic sediments accumulated within the foreland and a remnant ocean basin (which was commonly known as foredeep) was developed during Eocene. Moreover, the sediments were deposited by a large river draining the uplifted Himalayan belt during late Neogene. From the pattern of lithofacies, the river may be envisaged as braided type and was a bit shallow relative to its width, floored by bars and channels of low sinuosity and with a bed load of sand and pebbly sediments. These sediments present in the Arunachal foothills are bounded by the Brahmaputra Alluviums in the south and the Gondwana belt in the north and, by a system of frontal faults and the Main Boundary Fault, respectively. The sediments are mostly of molasse type (Upper Tertiary sediments), of different sedimentary facies present in the form of thick accumulation of multilateral and multistoried bodies. Moreover, the depositional basin suffered from some tectonic disturbances for which open folds and many reverse faults were formed. With the formation of foredeep infront of the Himalaya, a reversal of slope towards north-west took place in post-Barail times and during the later part of the Tertiary, the Himalayan and the Upper Assam basin were continuous below the Brahmaputra Alluviums as evidenced by field and laboratory observations. From these observations, it is seen that the Siwalik basin of Arunachal Himalaya has close resemblance with the Tertiary basin (Neogene basin) of Upper Assam rather than the Siwalik basin of western Himalaya and thus, this basin may be treated as a separate basin which may be renamed as "Tertiary basin of Arunachsl".

A NORTH WEST SHELF TRIASSIC REEF PLAY: RESULTS FROM ODP LEG 122

1989 ◽  
Vol 29 (1) ◽  
pp. 328 ◽  
Author(s):  
P.E. Williamson ◽  
N.F. Exon ◽  
B. ul Haq ◽  
U. von Rad
Keyword(s):  
Seismic Reflection ◽  
Upper Triassic ◽  
Seismic Facies ◽  
Late Triassic ◽  
Seismic Reflection Data ◽  
Reef Complex ◽  
North West ◽  
Exmouth Plateau ◽  
The North ◽  
Reflection Data

Site 764 of the Ocean Drilling Program (ODP), drilled during Leg 122 in the Exmouth Plateau region, cored 200 m of Upper Triassic (Rhaetian) reef complex. This site, on the northern Wombat Plateau (northernmost Exmouth Plateau) represents the first discovery of Triassic reefal material near the Australian North West Shelf. Seismic reflection data through Site 764 show that the reef itself corresponds predominantly to a seismically poorly reflective zone. A number of regional unconformities appear to correspond, however, to traceable seismic horizons which pass with reduced amplitude through the reef, indicating stages of reef growth separated by erosion or non- deposition. Seismic facies around the edges of the reef are consistent with the deposition of wedges of prograding reef- derived detritus.Application of the seismic criteria for reef recognition established at ODP Site 764, to other seismic reflection data on the Wombat Plateau, demonstrates that a major Upper Triassic reef complex fringes the margins of the Wombat Plateau. The Wombat Plateau lies at the western end of the North West Shelf, which was part of the southern margin of a warm Tethys Ocean in the Late Triassic, at a palaeolatitude of 25- 30°S. Upper Triassic reefs are known from southeast Indonesia and Papua New Guinea, and now the Wombat Plateau, and may be common elsewhere along the outer margin of the North West Shelf. Upper Triassic reef complexes, with their associated reservoir, source and seal facies, could represent an exciting new petroleum exploration play for the entire North West Shelf. Facies analysis suggests that they are likely only on the outer shelf and slope. Shallow Triassic reef complexes are clearly identifiable using high resolution seismic reflection data. Seismic reflection data of lower resolution may well reveal the associated detrital carbonate wedges, which are more laterally extensive than the reefal core, deeper in the section.

Controls on the preservation of Jurassic volcanism in the Northern Carnarvon Basin

2021 ◽  
Vol 61 (2) ◽  
pp. 600
Author(s):  
Michael Curtis ◽  
Simon Holford ◽  
Mark Bunch ◽  
Nick Schofield
Keyword(s):  
Early Cretaceous ◽  
Late Jurassic ◽  
Volcanic Centre ◽  
North West ◽  
The North ◽  
Igneous Provinces ◽  
Australian Continent ◽  
Northern Carnarvon Basin ◽  
Uplift And Erosion ◽  
Carnarvon Basin

The Northern Carnarvon Basin (NCB) forms part of the North West Australian margin. This ‘volcanic’ rifted margin formed as Greater India rifted from the Australian continent through the Jurassic, culminating in breakup in the Early Cretaceous. Late Jurassic to Early Cretaceous syn-rift intrusive magmatism spans 45000km2 of the western Exmouth Plateau and the Exmouth Sub-basin; however, there is little evidence of associated contemporaneous volcanic activity, with isolated late Jurassic volcanic centres present in the central Exmouth Sub-basin. The scarcity of observed volcanic centres is not typical of the extrusive components expected in such igneous provinces, where intrusive:extrusive ratios are typically 2–3:1. To address this, we have investigated the processes that led to the preservation of a volcanic centre near the Pyrenees field and the Toro Volcanic Centre (TVC). The volcanic centre near the Pyrenees field appears to have been preserved from erosion associated with the basin-wide KV unconformity by fault-related downthrow. However, the TVC, which was also affected by faulting, is located closer to the focus of regional early Cretaceous uplift along the Ningaloo Arch to the south and was partly eroded. With erosion of up to 2.6km estimated across the Ningaloo Arch, which, in places, removed all Jurassic strata, we propose that the ‘Exmouth Volcanic Province’ was originally much larger, extending south from the TVC into the southern Exmouth Sub-basin prior to regional uplift and erosion, accounting for the ‘missing’ volume of extrusive igneous material in the NCB.

Thermo-tectonic development of the Wandel Sea Basin, North Greenland

2020 ◽  
Author(s):  
Peter Japsen ◽  
Paul F. Green ◽  
James A. Chalmers
Keyword(s):  
Fault Zone ◽  
Vitrinite Reflectance ◽  
Sedimentary Basins ◽  
High Arctic ◽  
Fault Zones ◽  
The Arctic ◽  
Late Triassic ◽  
Ne Atlantic ◽  
Uplift And Erosion ◽  
North Greenland

<p>The Carboniferous to Palaeogene Wandel Sea Basin of North Greenland is an important piece in the puzzle of Arctic geology, particularly for understanding how the Paleocene–Eocene movement of the Greenland Plate relates to the compressional tectonics in the High Arctic; e.g. Eurekan Orogeny (arctic Canada), West Spitzbergen Orogeny (Svalbard) and Kronprins Christian Land Orogeny (North Greenland). We will refer collectively to these manifestations related to the movement of the Greenland Plate as the Eurekan Orogeny. Here, we present apatite fission-track analysis (AFTA) and vitrinite reflectance (VR) data combined with observations from the stratigraphic record to place constraints on the timing of key tectonic events.</p><p>Our study reveals a long history of episodic burial and exhumation since the collapse of the Palaeozoic fold belts along the east and north coasts of Greenland. Our results provide evidence for pre-Cenozoic phases of uplift and erosion in Early Permian, Late Triassic, Late Jurassic and mid-Cretaceous times, all of which involved removal of sedimentary covers that were 2 km thick or more.</p><p>Paleocene cooling and exhumation affected the major fault zones of the Wandel Sea Basin. The Paleocene episode thus defines the timing of the compressional event that caused folding and thrusting of Upper Cretaceous and older sediments along these fault zones. We conclude that the Paleocene inversion of the fault zones took place in the initial phase of the Eurekan Orogeny after the onset of seafloor spreading west of Greenland</p><p>Regional cooling, reflecting exhumation of the Wandel Sea Basin and surrounding regions, began at the end of the Eocene. Prior to the onset of exhumation, a cover of about 2.5 km of Paleocene–Eocene sediments had accumulated across a wide area. Northern Peary Land, north of the Harder Fjord Fault Zone, was uplifted about 1 km more than the area south of the fault zone during this episode. Regional denudation and reverse faulting that began at the end of the Eocene took place after the end of sea-floor spreading in the Labrador Sea and thus represent a post-Eurekan tectonic phase. A major plate reorganisation in the NE Atlantic and regional exhumation of West and East Greenland and adjacent Arctic regions took place at the same time, coinciding with a minimum of spreading rates in the NE Atlantic followed by expansion of the Iceland Plume.</p><p>Cooling from mid-late Miocene palaeotemperatures at sea level correspond to burial below a rock column about 1.8 km thick.</p><p>The preserved sedimentary sequences of the Wandel Sea Basin represent remnants of thicker strata, much of which was subsequently removed during multiple episodes of uplift and erosion. The thickness of these sedimentary covers implies that they must have extended substantially beyond the present-day outline of the basin, and thus that it at times was coherent with the sedimentary basins in the Arctic, as has been suggested from stratigraphic correlations.</p>

Multiple episodes of regional exhumation and inversion identified in the UK Southern North Sea based on integration of palaeothermal and palaeoburial indicators

2017 ◽  
Vol 8 (1) ◽  
pp. 47-65 ◽  
Author(s):  
Paul F. Green ◽  
Ian R. Duddy ◽  
Peter Japsen
Keyword(s):  
North Sea ◽  
Vitrinite Reflectance ◽  
Southern North Sea ◽  
The North ◽  
Regional Tectonic ◽  
The North Sea ◽  
The Uk ◽  
And Inversion ◽  
Multiple Episodes ◽  
Track Analysis

AbstractWe present a consistent synthesis of palaeothermal (apatite fission track analysis (AFTA) and vitrinite reflectance) data from UK Southern North Sea wells with the regional pattern of exhumation defined from sonic velocity data. Cenozoic exhumation across most of the region began in the Paleocene between 63 and 59 Ma. Amounts of removed section are around 1 km across the offshore platform, increasing to 2 km or more on the Sole Pit axis. Neogene exhumation within this area began between 22 and 15 Ma, and led to removal of up to 1 km of section. Along the eastern flank of the Sole Pit axis, sonic data define a pre-Chalk event, and AFTA data from these wells show that exhumation began between 120 and 93 Ma. This timing correlates with events defined from AFTA data in the Sorgenfrei–Tornquist Zone, further east, presumably reflecting a response to regional tectonic stresses. East of the Sole Pit axis, AFTA and sonic velocities suggest that Neogene exhumation dominates, while further east towards the central parts of the North Sea Mesozoic sediments appear to be at maximum burial today except for local effects related to salt movement. The multiple episodes of exhumation and burial defined here have important implications for exploration.

scholarly journals Estimating amount and timing of Late Palaeozoic uplift and erosion in the Rønne Graben, Bornholm, Denmark

1995 ◽  
Vol 42 ◽  
pp. 23-33
Author(s):  
Solvejg Kolbye Jensen ◽  
Søren Bom Nielsen
Keyword(s):  
Vitrinite Reflectance ◽  
Geothermal Gradient ◽  
Maximum Temperature ◽  
Model Parameter ◽  
Basin Modelling ◽  
Late Palaeozoic ◽  
Upper Silurian ◽  
Uplift And Erosion ◽  
Parameter Values ◽  
Reflectance Profile

Late Palaeozoic uplift and erosion is evidenced by a discontinuous vitrinite reflectance profile of the Pernille-1 well situated in the Rønne Graben. Modelling vitrinite reflectance evolution by the methods of basin modelling, the unconformity is estimated to represent Late Carboniferous uplift and erosion of 3,300 m of Upper Silurian and Devonian sediments. Given a vitrinite reflectance value of 1.7% at the erosional surface, the maximum temperature obtained during deepest burial is 160-165°C, corresponding to a geothermal gradient of approximately 50°C/km. The sensitivity of the erosion estimate to the choice of model parameter values is quantified. For example, a +10% uncertainty in the geothermal gradient equals an uncertainty of +400 m in the erosion estimate.

THE SUPPRESSION OF VITRINITE REFLECTANCE IN SOME NORTH WEST SHELF WELLS: BARROW-1, JUPITER-1 AND FLAMINGO-1

1992 ◽  
Vol 32 (1) ◽  
pp. 300 ◽  
Author(s):  
R.W.T. Wilkins ◽  
J.R. Wilmshurst ◽  
G. Hladky ◽  
M.V. Ellacott ◽  
C.P. Buckingham
Keyword(s):  
Organic Matter ◽  
Vitrinite Reflectance ◽  
Accurate Determination ◽  
Petroleum Exploration ◽  
Thermal Maturity ◽  
North West ◽  
The North ◽  
The Individual ◽  
Reflectance Data

The sediments of the North West Shelf pose several problems for the accurate determination of thermal maturity by vitrinite reflectance. There are some serious discrepancies between the results of different workers; in some wells there is a surprisingly small increase of reflectance with depth, and it is sometimes difficult to honour these data in thermal maturity modelling. There appear to be two major sources of error in the reflectance data. These are firstly, the effect known as 'suppression' of vitrinite reflectance, and secondly, the difficulty of identifying the vitrinite population in dispersed organic matter.These problems may be addressed by the fluorescence alteration technique which is closely related to vitrinite reflectance but has two special advantages. Firstly, it depends on an analysis of the fluorescence alteration response of a small representative population of organic matter in which the individual macerals need not be identified. Secondly, anomalous vitrinites with suppressed vitrinite reflectance are readily characterized, and the corrected equivalent reflectances determined.The technique has been tested on three North West Shelf petroleum exploration wells, Barrow-1, Jupiter-1 and Flamingo-1. Major discrepancies between measured and equivalent vitrinite reflectance appear to originate in part from the difficulty of identifying the vitrinite population in dispersed organic matter from marine sediments. There is also evidence of suppression of vitrinite reflectance in most samples from Barrow-1, in the Flamingo Group and Plover Formation of Flamingo-1, and in the upper part of the Mungaroo Formation of Jupiter-1.A model is proposed to facilitate the assessment of measured vitrinite reflectance data from Carnarvon or Bonaparte Basin wells. Suppression effects are likely to have influenced measured vitrinite reflectance results from wells for which the strongest data are obtained from the Lower Cretaceous fluvio-deltaic Barrow Group sediments or their equivalents.

Triassic paleogeography and petroleum systems of the North West Shelf, Australia: key insights from a new regional study

2017 ◽  
Vol 57 (2) ◽  
pp. 744
Author(s):  
Jarrad Grahame ◽  
Emma Cairns ◽  
Stephanie Roy
Keyword(s):  
System Development ◽  
New Ventures ◽  
Source Rocks ◽  
Late Triassic ◽  
Regional Study ◽  
North West ◽  
Petroleum Systems ◽  
The North ◽  
Core Logging ◽  
Seismic Sections

CGG Multi-Client & New Ventures, in collaboration with CGG Robertson, has undertaken a new comprehensive study of the Triassic paleogeography and petroleum systems of the North West Shelf (NWS) including the Northern Carnarvon, Roebuck, Browse and Bonaparte basins. The key objectives of the study were to enhance the understanding of the prospectivity of NWS Triassic petroleum systems, develop new paleogeography maps, establish evidence for Triassic marine-derived source rocks and investigate the prospectivity of Late Triassic carbonate reef complexes. The study comprises new biostratigraphic analyses, quantitative evaluation by scanning electron microscopy (QEMSCAN®) analyses, core logging, 1D and 2D modelling of key wells and seismic sections, plate reconstructed paleogeography and play mapping. Of key relevance to this study is the paleo-depositional framework and subsequent structuring of Triassic successions throughout the NWS basins in the context of petroleum system development.

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