Geology Reference
In-Depth Information
are the Jurassic-Valanginian, Hauterivian-Danian, Paleogene-Miocene and
Pliocene. Each of them has its own range of the excess formation pressure
(MPa) and abnormality factor (
К
AHFP
). Average values of these parameters
for individual waterhead complexes are: the Jurassic-Valanginian, 43.0 and
1.99; the Hauterivian-Danian, 23.1 and 1.44; the Paleogene - Miocene,
2.12; and the Pliocene-Anthropogene, 14.5 and 1.43. For approximate
global evaluations and comparisons with other basins, 26.9 MPa and 1.745
may be accepted as average values of the geo-fluid-dynamic status param-
eters for the South Caspian Basin sediment cover as a whole.
3.1.1.2
The Padan, Viennese, Irrawaddy-Andaman, Los
Angeles And Maracaibo Depressions
The identical qualitative situation is observed in the Padan, Viennese,
Irrawaddy-Andaman, Los Angeles and Maracaibo Depressions. In these
basins, stressed status of geo-hydrodynamic systems within local struc-
tures is observed, which is functionally associated with concentration
zones and areas of neotectonic processes (for instance in the Irrawaddy-
Andaman Depression: Anikeyev, 1964, 1977). Also recorded there is in
most cases continuous increase in the formation pressure abnormality fac-
tor with depth. Its average values are: Padan Basin, 1.53; Viennese Basin,
1.27; Irrawaddy-Andaman Basin, 1.57; Los Angeles Basin, 1.15; Maracaibo
Basin, 1.27 (Table 3.4, Figures 3.3-3.7).
As in the South Caspian, a typical feature of all these regions is the spa-
tial association of intense AHFP manifestations mostly with hydraulically
closed structures and within those, with the areas of most restricted water-
exchange (restricted development of faults, diapirism and mud volcanism).
In some regions, there is a relatively abrupt in some intervals of indi-
vidual areas (anticlinal zones) increase in maximum (and, therefore, the
average) values of the abnormality factor. This, at first sight, distorts the
general trend of increase down the sedimentary section. In the Padan
Depression, this phenomenon is noted, for instance, in the Pliocene com-
plex of the Fontanellato area, in the South Caspian, in the Pliocene of
the Baku Archipelago, in the Los Angeles, in the Torrance-Wilmington
Miocene zones (Kalinko, 1964; Mayuga, 1973; Rachinsky and Muradian,
1977; Fertl, 1980). The abnormality factors there reach maximum values
for the sediment cover of each region and are respectively 1.97; 1.90 and
1.40 (see Tables 3.1, 3.3, Figures 3.1, 3.3, 3.6). These phenomena should
apparently be considered a blockage result by thick regional seals of mov-
ing up vertical cross-flows of high-pressure fluids resulting in AHFP, also
a result of the development in these areas and intervals, beside epigenetic,
also syngenetic AHFP. The latter are causatively determined by the elevated
