Dissolution of apatite in North Sea Jurassic sandstones: implications for the generation of secondary porosity

Clay Minerals ◽  
1986 ◽  
Vol 21 (4) ◽  
pp. 711-733 ◽  
Author(s):  
A. C. Morton
Keyword(s):  
High Temperature ◽  
North Sea ◽  
Sedimentary Basins ◽  
Mineral Dissolution ◽  
Heavy Mineral ◽  
Heavy Minerals ◽  
Burial Depth ◽  
Pore Fluids ◽  
Secondary Porosity ◽  
Deep Burial

AbstractHeavy-mineral studies on Jurassic sandstones from the central and northern North Sea areas and from the Lossiemouth Borehole (onshore NE Scotland) show that the dissolution of apatite is a function of depositional environment rather than burial depth. In the shallow marine Upper Jurassic sands of the Claymore, Clyde and Tartan Fields, and in the deeper-water Magnus sands, apatite is ubiquitous, even where burial depths exceed 3800 m. Conversely, the fluvio-deltaic sands of the Beatrice, Heather, Ninian and Murchison Fields, and of the Lossiemouth Borehole, have suffered apatite dissolution, although burial depths range from very shallow (Lossiemouth Borehole) to about 3300 m. This clearly indicates that apatite dissolution has taken place through penetration of low-pH meteoric groundwaters at a very early stage in diagenesis, and that high-temperature fluids circulating in deep burial have had little or no effect. This is in accord with patterns of mineral dissolution observed in other sedimentary basins and in the North Sea Palaeocene. Although dissolution of heavy minerals is unlikely to generate significant secondary porosity, the process is nevertheless caused by the same pore-fluids that dissolve major framework constituents. Patterns of heavy-mineral dissolution therefore provide clues to the nature of these pore-fluids. Here, the relative stability of apatite is particularly significant. The order of stability apatite > garnet > kyanite, which characterizes deep burial of North Sea sandstones, has previously been simulated experimentally using fluids of pH 8 at room temperature. This suggests that high-temperature acidic pore-fluids may not have played a significant role in the development of secondary porosity in North Sea sandstones.

Stability of detrital heavy minerals in Tertiary sandstones from the North Sea Basin

Clay Minerals ◽  
1984 ◽  
Vol 19 (3) ◽  
pp. 287-308 ◽  
Author(s):  
A. C. Morton
Keyword(s):  
North Sea ◽  
Mineral Dissolution ◽  
Heavy Mineral ◽  
Heavy Minerals ◽  
Fluid Temperature ◽  
The North ◽  
Deep Burial ◽  
Mineral Stability ◽  
History Of ◽  
Temperature Rate

AbstractIntrastratal solution of detrital heavy minerals in North Sea Tertiary sandstones takes place in two different diagenetic settings, deep burial and acidic weathering. These are characterized by different orders of mineral stability: apatite, chloritoid, garnet, sphene and spinel are less stable in acidic weathering than in deep burial, whereas the reverse is true for andalusite, kyanite and sillimanite. Heavy-mineral dissolution patterns, therefore, do not follow one single order of stability but several, depending on the diagenetic environment in which the dissolution occurs. It seems from this that the relative order of stability for detrital heavy minerals is controlled by the chemistry of the interstitial waters, whereas the limits of persistence depend on pore-fluid temperature, rate of water throughput, and geological age. Because different diagenetic environments lead to differing orders of mineral stability, it may prove possible to elucidate certain aspects of the diagenetic history of a sandstone by heavy-mineral dissolution patterns.

Reduction and prediction of sandstone reservoir potential, Jurassic , North Sea

1985 ◽  
Vol 315 (1531) ◽  
pp. 187-202 ◽  
Keyword(s):  
North Sea ◽  
Burial Depth ◽  
Pore Waters ◽  
Secondary Porosity ◽  
Depth Data ◽  
General Decline ◽  
Mineral Compositions ◽  
The Difference ◽  
Detrital Mineral ◽  
Reservoir Potential

Porosity, permeability, mineralogical and depth data for two North Sea Jurassic sandstone sequences were analysed. Both sequences show statistically significant negative correlations between present burial depth and porosity. The influence of secondary porosity creation is subordinate to that of the general decline in porosity. For a given burial depth , sequence A is, on average, a little more porous (about 3%) than B. However, for a given porosity sequence A displays a permeability 1—3 orders of magnitude greater than B. The large permeability difference between A and B is a function of authigenic mineralogy. The only significant cement within the reservoir intervals of sequence A is quartz . Sequence B contains authigenic clays, quartz and subordinate carbonate. The abundant authigenic clay in B severely reduced permeability. In both instances, the cements are products of burial and were precipitated from pore waters expelled from shales during compaction. The expelled pore waters were both acidic and rich in solutes; a product of reactions between maturing organic matter, clays and iron oxides. The difference in authigenic mineralogy between the sequences was caused by the reaction between pore waters and sandstones with different detrital mineral compositions. Thus the present reservoir quality is a product of burial and of the reactions between evolving pore fluids and minerals in the sandstone.

Diagenetic carbonate and evaporite minerals in Rotliegend aeolian sandstones of the Southern North Sea: their nature and relationship to secondary porosity development

Clay Minerals ◽  
1986 ◽  
Vol 21 (4) ◽  
pp. 443-457 ◽  
Author(s):  
K. Pye ◽  
D. H. Krinsley
Keyword(s):  
North Sea ◽  
Secondary Porosity ◽  
Southern North Sea ◽  
Carbonate Cements ◽  
Deep Burial ◽  
Reducing Conditions ◽  
Two Generations ◽  
Stage 1 ◽  
Evaporite Minerals ◽  
Porosity Development

AbstractDeeply buried (> 3·5 km) Rotliegend aeolian sandstones in the Southern North Sea Basin display a number of interesting diagenetic features including (i) zoned iron-rich carbonate cements, (ii) anhydrite, halite and baryte cements, (iii) at least two generations of authigenic illite, and (iv) significant secondary porosity created by cement and framework-grain dissolution. The creation and destruction of secondary porosity is the result of changes in porewater chemistry during burial and subsequent uplift. Three pore-fluid regimes can be identified: (1) alkaline, oxidizing conditions during shallow to intermediate burial; (2) acid, reducing conditions during intermediate to deep burial; (3) alkaline, reducing conditions during deep burial and uplift. The transition from stage 1 to stage 2 was probably caused by expulsion of waters from the underlying Carboniferous shales. The transition to stage 3 probably began when faulting associated with uplift allowed invasion by alkaline fluids derived from Zechstein sediments.

Correspondence Analysis In Heavy Mineral Interpretation

1994 ◽  
Author(s):  
J. Tourenq ◽  
V. Rohrlich
Keyword(s):  
Principal Component Analysis ◽  
Correspondence Analysis ◽  
Principal Component ◽  
Sedimentary Basins ◽  
Component Analysis ◽  
Heavy Mineral ◽  
Heavy Minerals ◽  
Data Sets ◽  
Mineral Data ◽  
Non Parametric

Correspondence analysis, a non-parametric principal component analysis, has been used to analyze heavy mineral data so that variations between both samples and minerals can be studied simultaneously. Four data sets were selected to demonstrate the method. The first example, modern sediments from the River Nile, illustrates how correspondence analysis brings out extra details in heavy mineral associations. The other examples come from the Plio-Quaternary "Bourbonnais Formation" of the French Massif Central. The first data set demonstrates how the principal factor plane (with axes 1 and 2) highlights relationships between geographical position and the predominant heavy mineral association (metamorphic minerals and zircon), suggesting the paleogeographic source. In the second set, the factor plane of axes 1 and 3 indicates a subdivision of the metamorphic mineral assemblage, suggesting two sources of metamorphic minerals. Finally, outcrop samples were projected onto the factor plane and reveal ancient drainage systems important for the accumulation of the Bourbonnais sands. Statistical methods used in interpreting heavy minerals in sediments range from simple and classical methods, such as calculation of means and standard deviations, to the calculation of correspondences and variances. Use of multivariate methods is increasingly frequent (Maurer, 1983; Stattegger, 1986; 1987; Delaune et al., 1989; Mezzadri and Saccani, 1989) since the first studies of Imbrie and vanAndel (1964). Ordination techniques such as principal component analysis (Harman, 1961) synthesize large amounts of data and extract the most important relationships. We have chosen a non-parametric form of principal component analysis called correspondence analysis. This technique has been used in sedimentology by Chenet and Teil (1979) to investigate deep-sea samples, by Cojan and Teil (1982) and Mercier et al. (1987) to define paleoenvironments, and by Cojan and Beaudoin (1986) to show paleoecological control of deposition in French sedimentary basins. Correspondence analysis has been used successfully to interpret heavy mineral data (Tourenq et al, 1978a, 1978b; Bolin et al, 1982; Tourenq, 1986, 1989; Faulp et al, 1988; Ambroise et al, 1987). We provide examples of different situations where the method can be applied. We will not present the mathematical and statistical procedures involved in correspondence analysis, but refer readers to Benzécri et al.

Detrital zircon geochronology and heavy mineral analysis as complementary provenance tools in the presence of extensive weathering, reworking and recycling: the Neogene of the southern North Sea Basin

2021 ◽  
pp. 1-13
Author(s):  
Jasper Verhaegen ◽  
Hilmar von Eynatten ◽  
István Dunkl ◽  
Gert Jan Weltje
Keyword(s):  
North Sea ◽  
Chemical Weathering ◽  
Heavy Mineral ◽  
Mineral Analysis ◽  
Provenance Analysis ◽  
Detrital Zircon Geochronology ◽  
Southern North Sea ◽  
Variable Heavy ◽  
Mineral Data ◽  
Heavy Mineral Analysis

Abstract Heavy mineral analysis is a long-standing and valuable tool for sedimentary provenance analysis. Many studies have indicated that heavy mineral data can also be significantly affected by hydraulic sorting, weathering and reworking or recycling, leading to incomplete or erroneous provenance interpretations if they are used in isolation. By combining zircon U–Pb geochronology with heavy mineral data for the southern North Sea Basin, this study shows that the classic model of sediment mixing between a northern and a southern source throughout the Neogene is more complex. In contrast to the strongly variable heavy mineral composition, the zircon U–Pb age spectra are mostly constant for the studied samples. This provides a strong indication that most zircons had an initial similar northern source, yet the sediment has undergone intense chemical weathering on top of the Brabant Massif and Ardennes in the south. This weathered sediment was later recycled into the southern North Sea Basin through local rivers and the Meuse, leading to a weathered southern heavy mineral signature and a fresh northern heavy mineral signature, yet exhibiting a constant zircon U–Pb age signature. Thus, this study highlights the necessity of combining multiple provenance proxies to correctly account for weathering, reworking and recycling.

Heavy minerals in stream sediments from Churchill Falls, Labrador—an aid in bedrock mapping

1980 ◽  
Vol 17 (2) ◽  
pp. 244-253
Author(s):  
John Edward Callahan
Keyword(s):  
Frequency Distribution ◽  
Mineral Content ◽  
Regional Metamorphism ◽  
Stream Sediments ◽  
Heavy Mineral ◽  
Heavy Minerals ◽  
Sediment Samples ◽  
Fluvial Deposits ◽  
Geologic Map ◽  
High Concentrations

Stream sediments from a 13 000 km2 previously glaciated area in central Labrador near Churchill Falls were examined for their heavy mineral content. The minus 0.25 mm (60 mesh) nonmagnetic heavy mineral fraction from 846 stream sediment samples consists mainly of magnetite, ilmenite. garnet, hornblende, epidote and minor clinopyroxene, orthopyroxene. kyanite. sillimanite, biotite. apatite, and zircon. Changes in the frequency distribution of epidote, hornblende, garnet, and sillimanite in the stream sediments correspond well with those reported in previously mapped underlying bedrock lithologies. The occurrence of kyanite and sillimanite, high concentrations of garnet and opaques (mainly ilmenite), and lower concentrations of hornblende and epidote were used to determine grades of regional metamorphism, resulting in revision of the geologic map of this area. Heavy minerals in glacial drift or fluvial deposits may be useful as an aid in mapping in glaciated areas.

Seed Germination Ecology of Itchgrass (Rottboellia cochinchinensis)

Weed Science ◽  
2011 ◽  
Vol 59 (2) ◽  
pp. 182-187 ◽  
Author(s):  
Grace E-K. Bolfrey-Arku ◽  
Bhagirath S. Chauhan ◽  
David E. Johnson
Keyword(s):  
High Temperature ◽  
Seed Germination ◽  
Seedling Emergence ◽  
Soil Surface ◽  
The Philippines ◽  
Integrated Weed Management ◽  
Burial Depth ◽  
Soil Burial ◽  
Dark Regime ◽  
Temperature Pretreatment

Itchgrass is a weed of many crops throughout the tropics and one of the most important grass weeds of rainfed rice. Experiments were conducted in the laboratory and screenhouse to determine the effects of light, alternating day/night temperatures, high temperature pretreatment, water stress, seed burial depth, and rice residue on seed germination and seedling emergence of itchgrass in the Philippines. Two populations were evaluated and the results were consistent for both populations. Germination in the light/dark regime was greater at alternating day/night temperatures of 25/15 C than at 35/25, 30/20, or 20/10 C. Light was not a requirement for germination, but a light/dark regime increased germination by 96%, across temperature and population. A 5-min high temperature pretreatment for 50% inhibition of maximum itchgrass germination ranged from 145 to 151 C with no germination when seeds were exposed to ≥ 180 C. The osmotic potential required for 50% inhibition of maximum germination was −0.6 MPa for itchgrass, although some seeds germinated at −0.8 MPa. Seedling emergence was greatest for seeds placed on the soil surface, and emergence declined with increasing soil burial depth; no seedlings emerged from seeds buried at 10 cm. The addition of rice residue to soil surface in pots at rates equivalent to 4 to 6 Mg ha−1reduced itchgrass seedling emergence. Since seedling emergence was greatest at shallow depths and germination was stimulated by light, itchgrass may become a problem in systems where soil is cultivated at shallow depths. Knowledge gained in this study could contribute to developing components of integrated weed management strategies for itchgrass.

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