Clay mineralogy and pressure analysis from seismic information in Krishna‐Godavari basin, India

Geophysics ◽  
1990 ◽  
Vol 55 (11) ◽  
pp. 1447-1454 ◽  
Author(s):  
Saibal Basu
Keyword(s):  
Clay Mineral ◽  
Transit Time ◽  
East Coast ◽  
Clay Mineralogy ◽  
Seismic Velocities ◽  
Time Data ◽  
Mineral Associations ◽  
Sonic Logs ◽  
Godavari Basin ◽  
Pressure Analysis

Interval transit time data derived from seismic velocities have been analyzed to predict clay mineralogy and overpressures from compaction trends in the offshore areas of Krishna‐Godavari basin located on the east coast of India. Compaction trends from rms velocity fairly well match the trends obtained from sonic logs. This study has been extended to the undrilled part of the basin with the help of seismic information. Areal distribution of clay mineral types has been determined from the compaction trends. Prospective areas are identified on the basis of clay mineral distribution and overpressure zones related to the areas of different clay mineral associations.

Geological factors controlling clay mineral patterns across the Cretaceous-Tertiary boundary in Mediterranean and Atlantic sections

Clay Minerals ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 483-500 ◽  
Author(s):  
M. Ortega ◽  
I. Palomo ◽  
F. Martinez ◽  
I. Gonzalez
Keyword(s):  
Rare Earth ◽  
Clay Mineral ◽  
Clay Mineralogy ◽  
Mineral Association ◽  
Mineral Associations ◽  
Uppermost Layer ◽  
Regional Tectonic ◽  
Geological Factors ◽  
The Mediterranean ◽  
Layered Clay

AbstractThe clay mineral associations in the Cretaceous-Tertiary Boundary (KTB) and in the Danian and Maastrichtian levels of sections from the Mediterranean and the Atlantic Domains have been studied. The Mediterranean sections have a single mineral association consisting of smectiteiltite and kaolinite, whereas the Atlantic sections have several associations: illite-chlorite, illite-R1 I-S-kaolinite and illite-R 1 I-S-chlorite. Data are presented relating to the influence of K-feldspars and Fe oxide sphemles on the clay mineral associations. Study of rare-earth elements shows that regional geological factors affect the clay mineralogy of the KTB, examples showing significant anthigenesis in the Mediterranean sections, and important detrital supply in all the Atlantic sections. We propose that the KTB studied in these marine sections is equivalent to the uppermost layer of the two-layered clay unit originating in a cloud of a vapourized bolide. Regional tectonic conditions have been responsible for differences in clay sedimentation in these geological domains and among the stratigraphic sections of the Atlantic Domain.

Clay mineral associations in melanic soils of South Africa

Soil Research ◽  
2002 ◽  
Vol 40 (1) ◽  
pp. 115 ◽  
Author(s):  
Gertruida M. E. van der Merwe ◽  
Michiel C. Laker ◽  
Christl Bühmann
Keyword(s):  
South African ◽  
Clay Mineral ◽  
Wide Spectrum ◽  
Clay Fraction ◽  
Clay Mineralogy ◽  
Soil Classification ◽  
Large Degree ◽  
Mineral Associations ◽  
Investigative Technique ◽  
African Soil

The melanic horizon is 1 of 5 diagnostic topsoil horizons distinguished in the South African soil classification system. Melanic soils span a wide spectrum, ranging from those that intergrade with a vertic to those that intergrade with a humic horizon. Melanic soils are therefore expected to vary considerably with respect to a variety of physical, chemical, and clay mineralogical properties. The objective of the present study was to determine the clay mineral compositions of melanic horizons from 58 modal profiles and to establish to what extent melanic soil properties are related to clay mineralogy. Special emphasis was placed on the characterisation of the clay fraction in terms of group and species identification. X-ray diffractometry was employed almost exclusively as the investigative technique in mineral identification and quantification. Melanic A horizons showed a large degree of variation with regard to their clay mineral associations. More than half of the soils were dominated by smectite, 30% by kaolinite, and the rest by an association of about equal proportions of mica, kaolinite, and smectite. Talc and hydroxy-interlayered vermiculite occurred in a number of soils while one horizon was dominated by an illite/smectite interstratification. The smectite component was identified as belonging to either beidellite or vermiculite species, depending on the method employed. About a quarter of the smectitic soils contained montmorillonite as well but not as the dominant swelling phase. mollisols, clay mineralogy, layer charge.

Late Cretaceous—Palaeocene mid-latitude climates: inferences from clay mineralogy of continental-coastal sequences (Tremp-Graus area, southern Pyrenees, N Spain)

Clay Minerals ◽  
2011 ◽  
Vol 46 (1) ◽  
pp. 105-126 ◽  
Author(s):  
J. Arostegi ◽  
J. I. Baceta ◽  
V. Pujalte ◽  
M. Carracedo
Keyword(s):  
Clay Mineral ◽  
Chemical Weathering ◽  
Clay Mineralogy ◽  
Source Area ◽  
Climatic Conditions ◽  
Sem Images ◽  
Climatic Trend ◽  
Mineral Associations ◽  
Continental Basin ◽  
Mixed Layers

AbstractThe origin and distribution of late Maastrichtian–early Palaeocene clay mineral associations were investigated in the Tremp-Graus basin (South Pyrenees, Spain) to assess palaeoclimate changes during that period. The studied succession is made up of expanded continental and transitional terrigeneous and carbonate deposits accumulated in a coastal plain setting. X-ray diffraction, SEM-EDX and TEM-AEM analysis reveal that the main clay components are illite and smectite, but kaolinite, chlorite and illite-smectite mixed layers are present, although irregularly distributed, all of them showing a platy morphology typical of a detrital origin. Persistence of the chemical features of the Al-dioctahedral smectites throughout the whole succession demonstrates the persistence of the same source area during the interval studied. Palygorskite occurs in the late Danian and Selandian, within carbonate tidal flats as sabkha-like facies. In SEM images, the palygorskite displays straight fibre morphologies, both coating and branched curling out, a clear proof of authigenic origin.Physical or chemical weathering (PhW/ChW) determined as illite + chlorite/smectite + kaolinite ratio, smectite/kaolinite ratio and palygorskite distribution have been used as clay proxies for palaeoclimate reconstructions. Such data suggest a shift from temperate subhumid (perennial) conditions in late Maastrichtian times to a warm seasonal climate during early Palaeocene times. This trend, however, was dramatically altered during the late Danian–Selandian interval, when prevailing warm and semi-arid to arid climatic conditions caused intense evaporation and the development of an alkaline environment in which the palygorskite authigenesis took place.The proposed climatic trend partly concurs with that established for earliest Danian time by Domingoet al.(2007), also in the Tremp-Graus basin, from isotopic and geochemical proxies, as well as with the reconstruction of Cojan & Moreau (2006), in which a semiarid Danian phase for the near continental basin of Aix-en-Provence is postulated. However, it is at odds with the notion of a humid Danian state in the Pyrenees, as inferred by Gawendaet al.(1999) from clay mineral proxies of deep marine successions.

Clay mineral-grain size-calcite cement relationships in the Upper Cretaceous Chalk, UK: a preliminary investigation

Clay Minerals ◽  
2014 ◽  
Vol 49 (2) ◽  
pp. 299-325 ◽  
Author(s):  
C. V. Jeans ◽  
N. J . Tosca ◽  
X. F. Hu ◽  
S. Boreham
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Trace Element ◽  
Size Distribution ◽  
Clay Mineral ◽  
Preliminary Investigation ◽  
Clay Mineralogy ◽  
Minor Amount ◽  
Dioctahedral Smectite ◽  
Calcite Cement

AbstractThe idea is tested that the evolution of the Chalk’s clay mineral assemblage during diagenesis can be deduced by examining the relationships between its clay mineralogy, particle size distribution pattern, and the timing and trace element chemistry of the calcite cement. The preliminary results from five different examples of cementation developed at different stages of diagenesis in chalks with smectite-dominated clay assemblages suggest that this is a promising line of investigation. Soft chalks with minor amount of anoxic series calcite cement poor in Mg, Fe and Mn are associated with neoformed trioctahedral smectite and/or dioctahedral nontronite and talc. Hard ground chalk with extensive anoxic series calcite cement enriched in Mg and relatively high Fe, Mn and Sr are associated with neoformed glauconite sensu lato, berthierine and dioctahedral smectite, possibly enriched in Fe. The chalk associated with large ammonites shows extensive suboxic series calcite cement enriched in Mg, Mn and Fe that show no obvious correlation with its clay mineralogy. Nodular chalks with patchy suboxic series calcite cement enriched in Fe are associated with neoformed dioctahedral smectite, possibly enriched in Al, and berthierine. Regionally hardened chalk with extensive suboxic calcite cement and relatively high trace element contents contain pressure dissolution seams enriched in kaolin and berthierine. Laser-based particle-size distribution patterns suggest that each type of lithification has a typical complex clay mineral population, indicating that subtleties in mineralogy are not being identified and that there could be some control on the size and shape of the clay crystals by the different types of cementation.

Clay mineral distribution in the shelf sediments off the northern part of the east coast of India

1988 ◽  
Vol 8 (2) ◽  
pp. 145-151 ◽  
Author(s):  
V. Purnachandra Rao ◽  
N. Purnachander Reddy ◽  
Ch. Madhusudana Rao
Keyword(s):  
Clay Mineral ◽  
East Coast ◽  
Mineral Distribution ◽  
East Coast Of India ◽  
Shelf Sediments

Lung water measurements with the mean transit time approach

1985 ◽  
Vol 59 (3) ◽  
pp. 673-683 ◽  
Author(s):  
R. M. Effros
Keyword(s):  
Transit Time ◽  
Mean Transit Time ◽  
Tissue Perfusion ◽  
Time Data ◽  
Lung Water ◽  
Thermal Signal ◽  
The Mean ◽  
Points Of View ◽  
Vascular Obstruction ◽  
Pulmonary Vascular Obstruction

The potential usefulness and limitations of the double-indicator mean transit time approach for measuring lung water are evaluated from both theoretical and empirical points of view. It is concluded that poor tissue perfusion is the most serious factor that can compromise the reliability of this approach. Replacement of the conventional water isotopes with a thermal signal enhances indicator delivery to ischemic areas but the diffusion of heat is not sufficiently rapid to permit measurements of water in macroscopic collections of fluid which remain unperfused. The frequency of pulmonary vascular obstruction in patients with pulmonary edema related to lung injury suggests that interpretation of transit time data will be complicated by uncertainties concerning perfusion. Thermal-dye measurements of lung water may prove more helpful in situations where pulmonary blood flow remains relatively uniform.

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