- Home
- A-Z Publications
- Basin Research
- Previous Issues
- Volume 7, Issue 4, 1994
Basin Research - Volume 7, Issue 4, 1994
Volume 7, Issue 4, 1994
-
-
The blanketing effect in sedimentary basins
More LessAbstractThe deposition of cold sedimerlts, called thermal blanketing, is studied when the sedimentary basin is considered as part of the lithosphere. A general one‐dimensional temperature equation is obtained which accounts for blanketing, the movement of the lower boundary of the lithosphere, and the eventual stretching of the sediments and the lithosphere. These processes appear explicitly as convective terms in the model, which is a generalization of a previous temperature equation. The description of these processes b!‐means of convective terms is a major result in the paper; it makes these processes more amenable to quantitative investigations. The temperature equation is studied in two different settings; one where the lithosphere remains unstretched, and another where the lithosphere is subjected to constant strain rate stretching. The parameter controlling thermal blanketing in these models is the Peclet number. The transient period towards a stationary state, and the stationary state representing maximal blanketing are studied. Analytical expressions for various stationary states are obtained. When the lithosphere remains unstretched it is concluded that a necessary condition for strong blanketing is a sedimentation rate of the order of 250mMyr‐1. Where the sediments contribute to the heat flow by decay of radioactive isotopes, the radioactive heat production divided by the sedimentation rate should be at least 10‐9 (Wm‐3)/(mMyr‐1) for the heat production to compete with blanketing. During stretching of the lithosphere it is shown that for stretching factors (p) larger than 2, the convective effect of stretching the sediments contributes more to the reduction of the heat flow than the blanketing effect. Blanketing counteracts the increased heat flow caused by the stretching of the lithosphere, and the upwelling hot asthenosphere. With sedimentation rates inferred from isostatic calculations it is found that the strain rate times the initial crust thickness should be more than 0.25 km Myr‐1 for the blanketing effect to be noticeable. It is also shown that sediment infill which follows thermal subsidence, after a period of stretching, is not capable of blanketing.
-
-
-
Ottar Basin, SW Barents Sea: a major Upper Palaeozoic rift basin containing large volumes of deeply buried salt
More LessAbstractSeismic mapping and gravity modelling of the Ottar Basin ‐ a little studied Upper Palaeozoic graben in the south‐western Barents Sea ‐ demonstrates the presence of a major rift basin with large accumulations of unmobilized salt. Buried beneath thick, flat‐lying Mesozoic strata, the NE‐trending fault‐bounded basin is at least 170 km long, varies in width between 50 and 80 km and coincides with a negative gravity anomaly of more than — 10 mgal. Seismic observations show that the south‐western part is a half‐graben tilted to the north‐west whereas the north‐eastern part appears to be more symmetric in shape. A large mass deficiency in the north‐eastern part of the basin, indicated by a gravity anomaly of more than — 30 mgal, makes it necessary to postulate large amounts of salt within the basin. The preferred gravity model shows a total basin depth of 9.5 km, basin relief of 4.2 km and a salt volume of 6800 km3 corresponding to a 2.4‐km‐thick salt layer. Similar basin depths, but only 500–600 km3 of salt, are indicated beneath the Samson Dome in the south‐western part of the basin. Unlike salt bodies in other Barents Sea basins, the thick salt deposit in the north‐eastern part of the Ottar Basin is relatively unaffected by halokinesis. Interfingering of different basin facies, lack of tectonic reactivation of the basin and a relatively late differential loading by protruding cover strata probably explain these differences in development. The large size and voluminous salt deposits establish the Ottar Basin as one of the major Barents Sea evaporite basins and an important structural component of the Upper Palaeozoic rift system.
-
-
-
Oligocene to early Miocene tectono‐sedimentary history of the Alicante region (SE Spain): implications for Western Mediterranean evolution
By T. GeelAbstractThe Alicante region, situated at the intersection of major Western Mediterranean structural units, is unique in possessing a complete marine Oligocene to early Miocene record of both platform and slope deposits. Detailed analysis of three selected platform areas in the north of the region, each showing a different tectono‐sedimentary history, and comparison with coeval slope deposits in the south of the region shows that: (a) during the Rupelian to early Chattian the region formed part of the Iberian microplate and can be considered the south‐eastern continuation of the NW‐SE‐trending Iberian Chain (folding phase between 36 and 33 Ma, updoming event at 31–29 Ma, both induced by Pyrenean collision); (b) during the late Chattian to Aquitanian it was linked to the extensional, SW‐NE‐orientated Valencia Trough forming part of its western margin (rifting phases at 28 and 25 Ma); (c) from the Aquitanian‐Burdigalian boundary (20 Ma) onward, the region underwent NW‐directed compression due to Betic collision (folding phases at 20 and 17 Ma); (d) a foreland basin formed in the late Burdigalian (18–17 Ma), continuous from the Betic Cordilleras over the Alicante region to the Balearics; (e) a purely compressive regime was superseded by strike‐slip tectonics at the Langhian—Serravallian boundary.
The previously formulated hypotheses of coeval compression and extension with inferred hypothetical strike‐slip or other faults in or near the Alicante region is rejected on the basis that compress ional and extensional tectonics are separated in time in the Alicante region.
-
-
-
The interior rifts of the Yemen ‐ analysis of basin structure and stratigraphy in a regional plate tectonic context
Authors Phillip Redfern and Julie A. JonesAbstractThe full extent of Mesozoic rift basins within interior Yemen has only recently been established. This work presents a detailed documentation of the stratigraph)., structure and basin development of the Marib‐Shabwa and Sirr‐Sayun basins, and the Jeza Trough.
Yemen is located at the south‐western margin of the Arabian Plate, which for most of its early geological history formed part of the northern passive margin of Gondwanaland. Mesozoic break up of the super‐continent was associated with major rifting in the Late Jurassic (main phase) and Early Cretaceous. Orientation of the rift basins reflects an inheritance from deep‐seated Precambrian structural trends which cross the Arabian Plate.
The resultant structure of basement highs, tilted fault blocks, marginal terraces and central graben highs is illustrated in a series of detailed cross‐sections. A comprehensive stratigraphic framework has also been established for the Jurassic and Cretaceous basin‐fill, enabling thickness and facies variations to be analysed. This reveals a clear shift in the main period of fault‐related, high sediment accumulation rates, both within and across the three interior basins of Yemen.
In the western Marib‐Shabwa Basin, the fill is dominantly Late Jurassic, whilst the eastern Shabwa Basin and Sirr‐Sayun Basin exhibit a progressively increased, and younger, Early Cretaceous fill. The main period of fault‐related sedimentation in the most easterly basin, the Jeza Trough, is wholly Cretaceous.
Plate tectonic reconstructions of the area for this period have documented the separation and subsequent north‐eastward movement of the Indian Plate, away‐ from Africa‐Arabia. We believe this may have been the causal mechanism in the progressive eastward migration of rift activity in the Yemen.
-
-
-
BOOK REVIEWS
Book reviewed in this article:
Geologic Log Analysis Using Computer Methods (AAPG Computer Applications in Geology, No. 2) J. H. Doveton
Geology of the Mexican Republic D. Morán‐Zenteno
Arctic Geology and Petroleum Potential T. O. Vorren, E. Bergsager, Ø. A. Dahl‐Stamnes, E. Holter, B. Johansen, E. Lie & T. B. Lund (Eds)
Interior Rift Basins American AsSociation of Petroleum Geologists Memoir 59 S. M. Landon (Ed.)
The Petroleum System ‐from Source to Trap Leslie B. Magoon & Wallace G. Dow (Eds)
-
Volumes & issues
-
Volume 36 (2024)
-
Volume 35 (2023)
-
Volume 34 (2022)
-
Volume 33 (2021)
-
Volume 32 (2020)
-
Volume 31 (2019)
-
Volume 30 (2018)
-
Volume 29 (2017)
-
Volume 28 (2016)
-
Volume 27 (2015)
-
Volume 26 (2014)
-
Volume 25 (2013)
-
Volume 24 (2012)
-
Volume 23 (2011)
-
Volume 22 (2010)
-
Volume 21 (2009)
-
Volume 20 (2008)
-
Volume 19 (2007)
-
Volume 18 (2006)
-
Volume 17 (2005)
-
Volume 16 (2004)
-
Volume 15 (2003)
-
Volume 14 (2002)
-
Volume 13 (2001)
-
Volume 12 (2000)
-
Volume 11 (1999)
-
Volume 10 (1998)
-
Volume 9 (1997)
-
Volume 8 (1996)
-
Volume 7 (1994)
-
Volume 6 (1994)
-
Volume 5 (1993)
-
Volume 4 (1992)
-
Volume 3 (1991)
-
Volume 2 (1989)
-
Volume 1 (1988)