Geology Reference
In-Depth Information
(Table 2.12). The Table shows that the penetrated Paleocene-Pliocene sedi-
mentary section displays a trend to water salinity growth and alkalinity
decrease with stratigraphic depth.
The ground water component composition and salinity distribution
over the depression reflects a clear connection between the water medium
chemistry and paleogeographic depositional environment and facies of the
enclosing rocks. In the northern part of the region (the Northern, Chindwin
and Minbu troughs) with mostly continental fresh-water and deltaic section
(Bakirov, Varentsov and Bakirov, 1970; Geodekian, 1968; Krishnan, 1964;
Kuchapin, 1953), the lowest salinity and highest alkalinity waters are com-
mon (Taungtonlon, Vun-Tho, Indow, Seib, Chauk-Laniva, Enangyat and
other fields). In the southern part (the Delta, Sittang and North Sumatra
troughs) where the section comprises near-shore marine clastic facies,
ground waters have higher salinity and lower alkalinity (fields Henzada,
Prome, Myanaung, Pyapon, Rantau, Jedongdong and Djulu-Radjeu).
The available data indicate that the formation of low-salinity hydrocar-
bonate-sodium waters occurred first at the sediment-genesis and early dia-
genesis stages. At that time, the desalinated ooze (pore) waters interacted
with alkaline minerals in the enclosing rocks formed from the magmatites
of the surrounding mountain buildups Arakan Yoma, Shan, Pusat Gayo
and others, which were the clastic material provenance areas (Krishnan,
1964; Tainsh, 1950).
2.1.5
The Los Angeles Basin
The clastic section in the region includes alkaline and hard ground
waters (Table 2.13). The hydrocarbonate-sodium waters are typical of the
Pleistocene, Upper and Lower Pliocene waterhead complexes and the hard
waters, in the Jurassic, Upper Cretaceous, Middle- and Upper Miocene
ones. Regional water barriers are clays of the Eocene Santiago and Seste
formations and Upper Miocene Monterey formation. In some fields and
prospects local hard water shows against the general alkaline background
are also recorded in the Pliocene series (Repetto and Pico formations).
Ground waters from the
Jurassic
fractured Catalina Franciscan schists
forming the basement were produced in the Wilmington, Playa del Rey, El
Segundo and Long Beach fields. Their chemical composition is the chlo-
rine-calcium type. Total salinity is 125.1
−
139.5 mg.-equiv. (35.7
−
39.9 g/l)
and the secondary salinity factor, 13.9
17.2%-equiv. The values of these
parameters are maximal for the ground waters in all section intervals in
the region.
he
Upper Cretaceous
complex (Williams Fm.) is also saturated with the
chlorine-calcium waters. The flows were produced from arkose sandstones
−
