Arkell.1956.Jurassic..

THE ANDES OF SOUTH AMERICA 583
Virgatosphinctes mendozanus Burck.; also V. australis Burck., V. mexicanus
Burck., V. choicensis Burck., V. lotenoensis Weaver and abundant Inoceramus
curacoensis Weaver. (Weaver, 1931, pp. 46-7; Gerth, 1935,
table VIII). Perhaps 'Anavirgatites baylei' Spath came from this horizon
in Chile (Bayle & Coquand, 1851, pi. ii, fig. 2). A monograph by Indans
(1954) of the Perisphinctids from the Virgatosphinctes bed at the base of
the Tithonian in south Mendoza shows that in addition to this genus
the assemblage comprises typical Aulacosphinctoides (pi. xviii, figs. 1-7) and
species indistinguishable from Torquatisphinctes (pi. xx, figs. 2, 3) as in
Mexico, also Pseudinvoluticeras (pi. xv, 1) and the Dorsoplanites-like forms
mentioned above (pi. xx, figs. 1, 4, 5).
The preceding synopsis of the Tithonian and Berriasian of Argentina
follows the important revisions by Leanza (1945, 1947) with some stratigraphical
information from Weaver (1931). For numerous figures of the
ammonites from Argentina, Peru and Chile see Behrendsen (1891-2),
Burckhardt (1903), R. Douville (1910), Favre (1908), Feruglio (1937),
Gerth (1925a, 1926a), Haupt (1907), Krantz (1926, 1928), Leanza (1945),
Lisson (1908, 1937), Rivera (1951), Steuer (1897), Welter (1913), Indans
(!954)-
UNDATED
In Neuquen province, Argentina, the Tithonian shales rest transgressively
upon a considerable thickness of varicoloured sandstones and
red clays or clay shales of continental facies, which at Chacay-Melehue rest
in turn upon the marine basal Kimeridgian beds mentioned below (Leanza,
1947a). These unfossiliferous beds are presumably the same as the
upper part of the Loteno formation of Weaver, perhaps the highest 103 m.
down to the conglomerate (bed E) containing pebbles of acid lava in the
Picun Leufu anticline (Weaver, 1931, p. 42); for the mysterious 'Lusitanian
Virgatosphinctes' of bed N (ibid., p. 43, pis. 45, 46) have proved to be,
what they always looked in the drawings, Callovian Reineckiae (Herrero-
Ducloux & Leanza, 1943). In Chubut 500-1000 m. of continental deposits
intervene between the pre- or early-Tithonian volcanics and marine
Toarcian (Feruglio, 1949, p. 89).
LOWER KIMERIDGIAN
Immediately underlying the continental sandstones and shales at
Chacay-Melehue is a slightly dolomitic limestone containing Nebrodites,
Idoceras, Aspidoceras, Streblites (Pseudoppelia) and aptychi, assignable
to the lowest subzones of the Tenuilobatus Zone. The beds overlie and
also pass laterally into the main Gypsum formation (Leanza, 1946,
1947a).
Marine beds of about the same age occur also at Caracoles, near the
frontiers of Chile, Argentina and Bolivia, whence have been figured
the Crussol species Perisphinctes roubyanus and Nebrodites doublieri
(Steinmann, 1881, p. 298, and figs.).
http://jurassic.ru/