THE GEOLOGICAL EVOLUTION OF THE CONTINENTAL MARGIN OFF NORTHWEST AUSTRALIA

1976 ◽  
Vol 16 (1) ◽  
pp. 13 ◽  
Author(s):  
D.E. Powell
Keyword(s):  
Continental Margin ◽  
Middle Jurassic ◽  
Large Scale ◽  
Sedimentary Basins ◽  
Upper Jurassic ◽  
Hydrocarbon Generation ◽  
Carbonate Sediments ◽  
Intracratonic Basin ◽  
Uplift And Erosion ◽  
Depth Of Burial

The area comprising the Northwest Shelf of Australia is a good example of an 'Atlantic-type' continental margin. It is characterised by a series of major sedimentary basins of Mesozoic age, which generally parallel the present coastline. In each of these depocentres distinct lithotectonic units can be recognised which are related to phases of rifting and subsequent continental breakup. The pre-breakup rift valley and intracratonic basin stages are represented by a very thick Permian to Middle Jurassic series of mainly fluviodeltaic sediments. Breakup took place near the end of the Middle Jurassic and was accompanied by large-scale block faulting with associated uplift and erosion. As a result the ensuing Upper Jurassic to Lower Cretaceous marine transgression took place over a highly irregular palaeotopographic surface. With continuing post-breakup subsidence, open marine conditions became widespread by Upper Cretaceous time. Since the mid-Eocene the deposition of a thick prograding wedge of mainly carbonate sediments has given a general northwesterly regional tilt to the shelf. Such progradation is characteristic of a fully-evolved Atlantic-type continental margin.Hydrocarbon occurrences on the Northwest Shelf can be related to the tectonic evolution. Major gas/condensate discoveries have been encountered in fluviodeltaic reservoirs within the block-faulted pre-breakup sequence, sealed by post-breakup transgressive marine shales which also provide important source intervals. In addition, some sandstone units of the transgressive series are hydrocarbon-bearing. The prolonged post-breakup subsidence and accompanying thick sedimentation has ensured that source intervals have locally attained the necessary depth of burial for hydrocarbon generation.

The northwest Australian continental margin

1982 ◽  
Vol 305 (1489) ◽  
pp. 45-62 ◽  
Keyword(s):  
Early Cretaceous ◽  
Continental Margin ◽  
Middle Jurassic ◽  
Large Scale ◽  
Geothermal Gradient ◽  
Source Rocks ◽  
High Rate ◽  
Hydrocarbon Generation ◽  
Carbonate Sedimentation ◽  
Break Up

The Northwest Shelf of Australia offers a typical example of a ‘passive’ continental margin. Major intra-cratonic basins of Permian to Middle Jurassic age developed along the present coastline, superimposed to either orthogonally trending Palaeozoic basins or Precambrian basement rocks. In each of these depocentres distinct lithotectonic units can be recognized that are related to phases of rifting and subsequent continental break-up. The pre-break-up rift valley and intra-cratonic basin stages are represented by a very thick Permian to Middle Jurassic series of mainly fluvio-deltaic sediments but with occasional marine incursions. Break-up took place near the end of the Middle Jurassic and was accompanied by large-scale block faultings with associated uplift and sub-areal erosion. Gradually late Jurassic to early Cretaceous marine sediments transgressed over the eroded surface: within the general transgressive episode, late Callovian, late Oxfordian to Kimmeridgian, late Tithonian to early Cretaceous marine incursions may be singled out. Open marine conditions, related to the breakup of Gondwanaland and opening of the Indian Ocean, became widespread during the Albian in the southern part of the Australian Northwest Shelf and during the Cenomanian in the northern part. The deposition of a thick prograding wedge of mainly carbonate sedimentation since the mid-Eocene resulted in a northwesterly regional tilt of the Shelf. Hydrocarbon occurrences are related to the tectonic evolution. Early Triassic, early Middle Jurassic, late Oxfordian-Kimmeridgian and early Cretaceous marine incursions are directly related to the deposition of potential source rocks in restricted basins. A regressive phase led to the deposition of Triassic fluviatile sediments with excellent reservoir potential. Break-up tectonism and subsequent marine transgression provided the relevant trapping mechanism and probably the migration paths for the major gas-condensate discoveries of the Rankin Platform. The prolonged high rate of subsidence and accompanying thick sedimentation have ensured that hydrocarbon generation occurred, despite the low geothermal gradient.

Sequence stratigraphy of source and reservoir rocks in the Upper Permian and Jurassic of Jameson Land, East Greenland

1998 ◽  
pp. 43-54 ◽  
Author(s):  
Lars Stemmerik ◽  
Gregers Dam ◽  
Nanna Noe-Nygaard ◽  
Stefan Piasecki ◽  
Finn Surlyk
Keyword(s):  
Sequence Stratigraphy ◽  
Middle Jurassic ◽  
Sedimentary Basins ◽  
Upper Jurassic ◽  
Oil Field ◽  
Source Rocks ◽  
Upper Permian ◽  
Shallow Marine ◽  
East Greenland ◽  
Reservoir Rocks

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Stemmerik, L., Dam, G., Noe-Nygaard, N., Piasecki, S., & Surlyk, F. (1998). Sequence stratigraphy of source and reservoir rocks in the Upper Permian and Jurassic of Jameson Land, East Greenland. Geology of Greenland Survey Bulletin, 180, 43-54. https://doi.org/10.34194/ggub.v180.5085 _______________ Approximately half of the hydrocarbons discovered in the North Atlantic petroleum provinces are found in sandstones of latest Triassic – Jurassic age with the Middle Jurassic Brent Group, and its correlatives, being the economically most important reservoir unit accounting for approximately 25% of the reserves. Hydrocarbons in these reservoirs are generated mainly from the Upper Jurassic Kimmeridge Clay and its correlatives with additional contributions from Middle Jurassic coal, Lower Jurassic marine shales and Devonian lacustrine shales. Equivalents to these deeply buried rocks crop out in the well-exposed sedimentary basins of East Greenland where more detailed studies are possible and these basins are frequently used for analogue studies (Fig. 1). Investigations in East Greenland have documented four major organic-rich shale units which are potential source rocks for hydrocarbons. They include marine shales of the Upper Permian Ravnefjeld Formation (Fig. 2), the Middle Jurassic Sortehat Formation and the Upper Jurassic Hareelv Formation (Fig. 4) and lacustrine shales of the uppermost Triassic – lowermost Jurassic Kap Stewart Group (Fig. 3; Surlyk et al. 1986b; Dam & Christiansen 1990; Christiansen et al. 1992, 1993; Dam et al. 1995; Krabbe 1996). Potential reservoir units include Upper Permian shallow marine platform and build-up carbonates of the Wegener Halvø Formation, lacustrine sandstones of the Rhaetian–Sinemurian Kap Stewart Group and marine sandstones of the Pliensbachian–Aalenian Neill Klinter Group, the Upper Bajocian – Callovian Pelion Formation and Upper Oxfordian – Kimmeridgian Hareelv Formation (Figs 2–4; Christiansen et al. 1992). The Jurassic sandstones of Jameson Land are well known as excellent analogues for hydrocarbon reservoirs in the northern North Sea and offshore mid-Norway. The best documented examples are the turbidite sands of the Hareelv Formation as an analogue for the Magnus oil field and the many Paleogene oil and gas fields, the shallow marine Pelion Formation as an analogue for the Brent Group in the Viking Graben and correlative Garn Group of the Norwegian Shelf, the Neill Klinter Group as an analogue for the Tilje, Ror, Ile and Not Formations and the Kap Stewart Group for the Åre Formation (Surlyk 1987, 1991; Dam & Surlyk 1995; Dam et al. 1995; Surlyk & Noe-Nygaard 1995; Engkilde & Surlyk in press). The presence of pre-Late Jurassic source rocks in Jameson Land suggests the presence of correlative source rocks offshore mid-Norway where the Upper Jurassic source rocks are not sufficiently deeply buried to generate hydrocarbons. The Upper Permian Ravnefjeld Formation in particular provides a useful source rock analogue both there and in more distant areas such as the Barents Sea. The present paper is a summary of a research project supported by the Danish Ministry of Environment and Energy (Piasecki et al. 1994). The aim of the project is to improve our understanding of the distribution of source and reservoir rocks by the application of sequence stratigraphy to the basin analysis. We have focused on the Upper Permian and uppermost Triassic– Jurassic successions where the presence of source and reservoir rocks are well documented from previous studies. Field work during the summer of 1993 included biostratigraphic, sedimentological and sequence stratigraphic studies of selected time slices and was supplemented by drilling of 11 shallow cores (Piasecki et al. 1994). The results so far arising from this work are collected in Piasecki et al. (1997), and the present summary highlights the petroleum-related implications.

LATERAL AND VERTICAL RANK VARIATION: IMPLICATIONS FOR HYDROCARBON EXPLORATION

1978 ◽  
Vol 18 (1) ◽  
pp. 143 ◽  
Author(s):  
A.J Kantsler ◽  
G. C. Smith ◽  
A. C. Cook
Keyword(s):  
Vitrinite Reflectance ◽  
Sedimentary Basins ◽  
Hydrocarbon Exploration ◽  
Hydrocarbon Generation ◽  
Marked Rise ◽  
Canning Basin ◽  
Early Maturation ◽  
Late Tertiary ◽  
Uplift And Erosion ◽  
Gas Fields

Vitrinite reflectance measurements are used to determine the vertical and lateral patterns of rank variation within four Australian sedimentary basins. They are also used to estimate palaeotemperatures which, in conjunction with present well temperatures, allow an appraisal of the timing of coalification and of hydrocarbon generation and distribution.The Canning Basin has a pattern of significant pre-Jurassic coalification which was interrupted by widespread uplift and erosion in the Triassic. Mesozoic and Tertiary coalification is generally weak, resulting in a pattern of rank distribution unfavourable to oil occurrence but indicating some potential for gas. The Cooper Basin also has a depositional break in the Triassic, but the post-Triassic coalification is much more significant than in the Canning Basin. The major gas fields are in, or peripheral to, areas which underwent strong, early, telemagmatic coalification whereas the oil-prone Tirrawarra area is characterized by a marked rise in temperature in the late Tertiary. The deeper parts of the Bass Basin underwent early coalification and are in the zone of oil generation, while most of the remaining area is immature. Inshore areas of the Gippsland Basin are also characterized by early coalification. Areas which are further offshore are less affected by this phase of early maturation, but underwent rapid burial and a sharp rise in temperature in the late Tertiary.

Rift systems of the East Siberian basin, Arctic region

2020 ◽  
Author(s):  
Nickolay Zhukov ◽  
Anatoly Nikishin ◽  
Eugene Petrov
Keyword(s):  
Continental Margin ◽  
Large Scale ◽  
Block Structure ◽  
Sedimentary Basins ◽  
Rift System ◽  
Northwestern Part ◽  
Gravitational Fields ◽  
Stage Of Development ◽  
East Siberian Sea ◽  
Seismic Lines

<p>The growing interest of geoscientists to the Eastern Arctic shelf is caused one of the most important problems of the present time – the creation of a tectonic model for assessing the hydrocarbon potential of the Eastern Arctic basins. In this time, over the past decade, the study of the East Siberian sea seismic lines have increased. Now, we operated a new seismic data, the interpretation of which gives the key to understanding the structure of the East Siberian continental margin.</p><p>This paper presents an analysis of the tectonic structure and geological history of the shelf of the East Siberian continental margin based on the interpretation of seismic lines in conjunction with geological information.</p><p>The modern ideas of the East Arctic rift tectonic evolution and formation of sedimentary basins over the entire East Siberian shelf resulted from the large-scale tectonic and magmatism events took place and the intense rifting or stretching phase widespread the entire shelf in the Albian-Aptian.</p><p>The East Siberian basin includes the main structural elements, formed in a postcollisional destructive stage of development – the New Siberian rift, the De Long uplift, the Zhokhov Foredeep basin, the Melville trough, the Baranov rise, the Pegtymel trough, the Shelagskoe rise.</p><p><strong>The New Siberian rift</strong> is located between the elevations of the New Siberian Islands and the archipelago De Long. Rift extends in a southeast direction from the East-Anisin Trough deflection to the Islands of Faddeev Island and New Siberia Islands. The New Siberian rift is a bright negative structural element and clearly stands out on the maps of the anomalous magnetic and gravitational fields, contrasting with the positive anomalies of surrounding rises and ridges.</p><p><strong>De Long Plateau</strong> is a large positive structure. The uplift boundaries and internal structure are clearly visible in the gravitational and magnetic fields. The magnetic anomaly expressed in the De long, it is a typical for the areas of development of volcanogenic formations and basalts trap magmatism.</p><p><strong>The East Siberian Rift System</strong> located from the northwestern part of the De long Plateau to the eastern part of the North Chukchi basin. System includes the <strong>Melville trough</strong> in the southern part of the East Siberian Sea. The reflector packages on seismic lines in the De Long Plateau and The East Siberian Rift System indicate that continental rifting occurred over the mantle plum.</p><p>The length of the Melville trough is a 350-370 km; with a width of 100-150 km. Trough is the symmetrical deflection consists of two narrow rifts separated by a rise.</p><p>The eastern branch of the rift system of the Melville trough joins the <strong>Baranov rise</strong>. The Baranov rise has a block structure with the geometry of which is similar to the block structure of the De-Long Plateau.</p><p><strong>The Dremkhed</strong> <strong>trough</strong> is a deep rift structure transitional between the East Siberian and North Chukchi basins, the thickness of the sedimentary cover in central part of section is 7000 ms.</p><p>The study was funded by RFBR project - 18-05-70011.</p>

Large-scale intraplate deformation caused the cementation of Jurassic carbonates in the eastern Paris Basin

2020 ◽  
Author(s):  
Thomas Blaise ◽  
Benjamin Brigaud ◽  
Cédric Carpentier
Keyword(s):  
Middle Jurassic ◽  
Carbonate Rocks ◽  
Large Scale ◽  
Pore Space ◽  
Upper Jurassic ◽  
Late Eocene ◽  
Rift System ◽  
Paris Basin ◽  
Carbonate Platforms ◽  
Icp Ms

<p>In the eastern Paris Basin, the Oxfordian (Upper Jurassic) and Bathonian to Bajocian (Middle Jurassic) carbonate platforms have been intensively cemented, despite rather low burial (< 1000 m). These limestone units are separated from each other by a 150 m thick succession of Callovian - Oxfordian clay-rich rocks. These claystones are currently under investigation by the French national radioactive waste management agency (Andra).</p><p>Most of the initial porosity in the Middle and Upper Jurassic limestones is now sealed by successive stages of calcite precipitation, which have been thoroughly characterized both petrographically and geochemically over the last fifteen years (Buschaert et al., 2004; Vincent et al., 2007; Brigaud et al., 2009; André et al., 2010; Carpentier et al., 2014). However, despite these research efforts, the timing and temperature of the fluids involved in the cementation of these carbonate rocks were still uncertain.    </p><p>Here, we present and discuss newly acquired ∆<sub>47</sub> temperatures and U-Pb ages of calcite cements filling the intergranular pore space, as well as vugs and microfractures.</p><p>The Middle Jurassic limestones were largely cemented during the Late Jurassic / Early Cretaceous period, as shown by our new LA-ICP-MS U-Pb ages that agree with the previous Isotope Dilution-TIMS U-Pb age of 147.8 ± 3.8 Ma from Pisapia et al. (2017). This event is believed to be associated to the Bay of Biscay rifting. Our data also reveal a second and more discrete crystallization event during the Late Eocene / Oligocene period, related to the European Cenozoic Rift System (ECRIS). In both cases, calcite was precipitated from fluids in thermal disequilibrium with the host rocks. </p><p>By contrast, the Upper Jurassic limestones were largely affected by the successive deformation events that occurred during the Late Mesozoic / Cenozoic period. New LA-ICP-MS U-Pb ages acquired in ca. 200 µm-thick fractures reveal that calcite crystallized during three successive periods corresponding to the Pyrenean compression, the ECRIS extension and, finally, during the Alpine compression. These compression phases generated late stylolitization and subsequent dissolution/recrystallization in the Upper Jurassic limestones, while such tectonic features are rare in the Middle Jurassic.</p><p>Therefore, as opposed to the more conventional « burial-induced » model, our study highlights the role of stress propagation in the cementation of carbonate rocks hundreds of kilometers away from the rifting or collisional areas.</p><p>References:</p><p>Buschaert et al., 2004. Applied Geochemistry 19, 1201 – 1215. Vincent et al., 2007. Sedimentary Geology 197, 267 – 289. Brigaud et al., 2009. Sedimentary Geology 222, 161 – 180. André et al., 2010. Tectonophysics 490, 214 – 228. Carpentier et al., 2014. Marine and Petroleum Geology 53, 44 – 70. Pisapia et al., 2017. Journal of the Geological Society of London 175, 60 – 70.</p>

Evolution of the Pacific Margin, Vancouver Island, and adjacent regions

1977 ◽  
Vol 14 (9) ◽  
pp. 2062-2085 ◽  
Author(s):  
J. E. Muller
Keyword(s):  
Subduction Zone ◽  
Continental Margin ◽  
Upper Jurassic ◽  
Vancouver Island ◽  
Late Eocene ◽  
Volcanic Arc ◽  
Late Mesozoic ◽  
Clastic Sediments ◽  
The Pacific ◽  
Uplift And Erosion

The tectonic–stratigraphic evolution of Vancouver Island, a part of the Insular Belt, is reviewed as it relates to the other major tectonic belts recognized in the western Cordillera of Canada and the adjacent United States. The Pacific Belt, recognized south of the international border, is also identified in the west and south of the island. Oldest rocks of the Insular Belt are a late Paleozoic volcanic arc terrane and a crystalline 'basement' that is probably pre-Devonian. A thick Upper Triassic succession of tholeiitic pillow lavas and flows, overlain by carbonate–clastic sediments, rests in part on the Paleozoic. Elsewhere the tholeiite may represent oceanic floor, perhaps formed when the Insular Belt was fragmented and rifted off the continental margin far to the south. Above it the Early Jurassic volcanic arc with related batholiths may have been aligned with a similar terrane in the Intermontane Belt before the two belts assumed parallel positions in late Mesozoic time. An Upper Jurassic – Lower Cretaceous westward thickening clastic wedge indicates uplift and erosion of the volcanic arc in late Mesozoic time. Further west the 'inner Pacific Belt' of Jura-Cretaceous elastics and chert represent slope and trench deposits that have been deformed to mélange or converted to schist. They are coeval and homologous to Franciscan and Chugach Terranes and probably mark the late Mesozoic trench and subduction zone along the continental margin. The Coast Plutonic Belt represents the related volcanic arc, and pre-Cretaceous Insular Belt rocks, unconformably overlain by Cretaceous clastic sediments, represent the arc–trench gap and fore-arc basin. Until Late Cretaceous time convergence of the Insular and Pacific Belts occurred along San Juan Fault. In early Tertiary time Eocene oceanic basalt (Outer Pacific Belt) and Jura-Cretaceous metasediments (Inner Pacific Belt) converged by under-thrusting and (or) strike–slip faulting along Leech River Fault. In Late Eocene time the trench and subduction zone shifted westward to the present core zone of the Olympic Mountains and shifted again in Miocene time to its present position.

scholarly journals Post-rift landscape development of north-east Brazil

1969 ◽  
Vol 17 ◽  
pp. 81-84 ◽  
Author(s):  
Johan M. Bonow ◽  
Peter Japsen ◽  
Paul F. Green ◽  
Peter R. Cobbold ◽  
Augusto J. Pedreira ◽  
...  
Keyword(s):  
Large Scale ◽  
Sedimentary Cover ◽  
Hydrocarbon Exploration ◽  
Hydrocarbon Generation ◽  
Migration Routes ◽  
North East ◽  
Geological Past ◽  
Regional Tectonic ◽  
High Level ◽  
Uplift And Erosion

The evolution of the landscape of north-east Brazil in relation to the burial and exhumation history of both onshore and offshore areas is the focus of a research project carried out for StatoilHydro do Brasil and Petrobras from 2007 to 2009 by the Geological Survey of Denmark and Greenland in collaboration with Geotrack International. In hydrocarbon exploration it is important to understand the regional tectonic framework and thus also to consider the volumes of rocks that may have been present and then removed during the geological past. For example, the timing of hydrocarbon generation and changes in migration routes can be assessed when the timing and magnitude of uplift and erosion is known. Studies in West Greenland have demonstrated the usefulness of large-scale, low-relief, high-level landscapes as markers of uplift events, and in particular the strength of combining the denudation history from landscape analysis with the cooling history from apatite fission-track analysis (AFTA) data and the stratigraphic record (Bonow et al. 2006, 2007; Japsen et al. 2006, 2009). In the study area, there are two plateaux with elevations up to c. 1300 m above sea level (a.s.l.). The plateaux are currently being dissected by deeply incised fluvial valleys, and escarpments separate the two plateaux. The lowlands cut across Early Cretaceous rift systems along the Atlantic margin, including the intracontinental Recôncavo–Tucano–Jatobá (RTJ) Rift and also the Camamu Basin, of which the western margin is exposed onshore (Fig. 1). The RTJ Rift is a mature hydrocarbon province, whereas the deep-water parts of the Camamu Basin are the target of frontier exploration (e.g. Magnavita et al. 1994; Davison 1999; Cobbold et al. 2008). The post-rift sequence in the RTJ Rift and the inshore Camamu Basin is thin or absent. However, it has been estimated that up to 2000 m of sedimentary cover once was present, but has now been removed (Magnavita et al. 1994).

A REGIONAL INTERPRETATION OF THE BROWSE BASIN

1978 ◽  
Vol 18 (1) ◽  
pp. 23 ◽  
Author(s):  
G. A. Allen ◽  
L. G. G. Pearce ◽  
W. E. Gardner
Keyword(s):  
Ocean Circulation ◽  
Continental Margin ◽  
Middle Jurassic ◽  
Depositional Environment ◽  
Important Change ◽  
Structural Elements ◽  
Seaward Edge ◽  
Geological Event ◽  
Intracratonic Basin ◽  
Block Faulting

The Browse Basin, off the northwest coast of Australia, originated as an intracratonic basin. It resulted from tensional movements and developed into an Atlantic-type continental margin. Sedimentation, which commenced in the Late Carboniferous and extended through the Middle Jurassic, is confined mostly to a linear, northeast-trending depocentre located between the onshore Kimberley Block and the Scott Plateau to the west. This sedimentary series is characterised by rift valley type deposits laid down between successive episodes of tectonism. Tectonism near the end of the Middle Jurassic was associated with breakup of the continent along what developed as the seaward edge of the Scott Plateau. This geological event marks an important change in the depositional environment of the basin from pre-breakup, mainly paralic and fluviodeltaic to post-breakup, transgressive marine conditions. The post-breakup series was formed under relative tectonic quiescence, except for some local structural rejuvenation and regional subsidence of the outer continental margin which eventually resulted in the deposition of Cretaceous and Tertiary sediments across the Scott Plateau. A fully open marine environment, however, was not achieved basinwide until during the Late Cretaceous, when the Scott Plateau had subsided sufficiently to allow unrestricted ocean circulation. Evolution of the basin was completed by a seaward prograding, mainly carbonate Tertiary wedge.Geophysical data show several sub-parallel, structurally high Mesozoic trends, oriented towards the northeast. The Scott Reef gas/condensate discovery lies on one such trend. The structural elements were interpreted as being mostly initiated prior to breakup by episodes of block faulting which produced a horst and graben topography. The horst blocks were subsequently onlapped and draped by the post-breakup sediments. The hydrocarbon accumulation at Scott Reef is restricted to the horst block reservoirs, but hydrocarbon indications elsewhere within the basin in the post-breakup series suggest that accumulations could also exist in this section.

Relationships between intraplate deformations and the cementation of Jurassic carbonates in the eastern Paris Basin revealed by calcite U-Pb geochronology and ∆47 thermometry

2021 ◽  
Author(s):  
Thomas Blaise ◽  
Benjamin Brigaud ◽  
Cédric Carpentier ◽  
Xavier Mangenot
Keyword(s):  
Middle Jurassic ◽  
Carbonate Rocks ◽  
Large Scale ◽  
Pore Space ◽  
Upper Jurassic ◽  
Radiometric Dating ◽  
Rift System ◽  
Burial History ◽  
Paris Basin ◽  
Icp Ms

<p>In the eastern Paris Basin, the Oxfordian (Upper Jurassic) and Bathonian to Bajocian (Middle Jurassic) carbonate platforms have been intensively cemented, despite a relatively low burial history (< 1000 m). These limestones units are separated by a 150 m thick succession of Callovian-Oxfordian tight clay-rich rocks that are currently investigated by the French national radioactive waste management agency (Andra).</p><p>Most of the initial porosity in the Middle and Upper Jurassic limestones is now cemented by successive stages of calcite, which were thoroughly characterized both petrographically and geochemically over the last fifteen years (Buschaert et al., 2004; Vincent et al., 2007; Brigaud et al., 2009; André et al., 2010; Carpentier et al., 2014). However, despite such research efforts, the timing and temperature of the fluids involved in the cementation of these carbonate rocks are still debated.    </p><p>Here, we complement these efforts by coupling ∆<sub>47</sub> temperatures and U-Pb ages on calcite cement filling tectonic microfractures, as well as the intergranular pore space and vugs.</p><p>Our findings indicates that the Middle Jurassic limestones were largely cemented during the Late Jurassic / Early Cretaceous period, with new LA-ICP-MS U-Pb ages (Brigaud et al., 2020) in agreement with previously published Isotope Dilution-TIMS U-Pb age of 147.8 ± 3.8 Ma (Pisapia et al., 2017). This event is believed to be associated to the Bay of Biscay rifting. A second and more discrete crystallization event occurred during the Late Eocene / Oligocene period, related to the European Cenozoic Rift System (ECRIS).</p><p>The Upper Jurassic limestones were by contrast affected by a broader range of successive deformation events spanning the Late Mesozoic / Cenozoic period. New LA-ICP-MS U-Pb ages acquired in ca. 200 µm-thick fractures show that calcite crystallized during three successive periods corresponding respectively to the Pyrenean compression, the ECRIS extension and the Alpine compression.</p><p>Our study highlights tectonic stress propagation across hundreds of kilometers, from the rifting or collisional areas toward the cementation area of carbonate rocks. Thanks to the direct radiometric dating and clumped isotope thermometry of calcite cements in microfractures, a refined paragenetic sequence is proposed with emphasis on the genetic link between large-scale deformation and calcite precipitation.</p><p>References :</p><p>Buschaert et al., 2004. Applied Geochemistry 19, 1201 – 1215. Vincent et al., 2007. Sedimentary Geology 197, 267 – 289. Brigaud et al., 2009. Sedimentary Geology 222, 161 – 180. André et al., 2010. Tectonophysics 490, 214 – 228. Carpentier et al., 2014. Marine and Petroleum Geology 53, 44 – 70. Pisapia et al., 2017. Journal of the Geological Society of London 175, 60 – 70. Brigaud et al., 2020. Geology 48, 851 – 856.</p>

Two-dimensional elastic pseudo-spectral modeling of wide-aperture seismic array data with application to the Wichita Uplift-Anadarko Basin region of southwestern Oklahoma

1990 ◽  
Vol 80 (6A) ◽  
pp. 1677-1695 ◽  
Author(s):  
Ik Bum Kang ◽  
George A. McMechan
Keyword(s):  
Large Scale ◽  
Deep Structure ◽  
Sedimentary Basins ◽  
P Wave ◽  
Two Dimensional ◽  
Anadarko Basin ◽  
Near Surface ◽  
University Of Texas ◽  
Wide Aperture ◽  
The University

Abstract Full wave field modeling of wide-aperture data is performed with a pseudospectral implementation of the elastic wave equation. This approach naturally produces three-component stress and two-component particle displacement, velocity, and acceleration seismograms for compressional, shear, and Rayleigh waves. It also has distinct advantages in terms of computational requirements over finite-differencing when data from large-scale structures are to be modeled at high frequencies. The algorithm is applied to iterative two-dimensional modeling of seismograms from a survey performed in 1985 by The University of Texas at El Paso and The University of Texas at Dallas across the Anadarko basin and the Wichita Mountains in southwestern Oklahoma. The results provide an independent look at details of near-surface structure and reflector configurations. Near-surface (<3 km deep) structure and scattering effects account for a large percentage (>70 per cent) of the energy in the observed seismograms. The interpretation of the data is consistent with the results of previous studies of these data, but provides considerably more detail. Overall, the P-wave velocities in the Wichita Uplift are more typical of the middle crust than the upper crust (5.3 to 7.1 km/sec). At the surface, the uplift is either exposed as weathered outcrop (5.0 to 5.3 km/sec) or is overlain with sediments of up to 0.4 km in thickness, ranging in velocity from 2.7 to 3.4 km/sec, generally increasing with depth. The core of the uplift is relatively seismically transparent. A very clear, coherent reflection is observed from the Mountain View fault, which dips at ≈40° to the southwest, to at least 12 km depth. Velocities in the Anadarko Basin are typical of sedimentary basins; there is a general increase from ≈2.7 km/sec at the surface to ≈5.9 km/sec at ≈16 km depth, with discontinuous reflections at depths of ≈8, 10, 12, and 16 km.

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