Middle Devonian lycopsids from high southern palaeolatitudes of Gondwana (Argentina).

CINGOLANI, C.A.; BERRY, C.; MOREL, E.; TOMEZZOLI R.N.

GEOLOGICAL MAGAZINE

CAMBRIDGE UNIV PRESS

Lugar: Cambridge; Año: 2002 vol. 139 p. 641 - 649

0016-7568

Abstract – Fossil plants are described from the upper part of the Devonian Lolén Formation, Sierra dela Ventana, Buenos Aires Province, Argentina, in the area of Estancia Las Acacias. The sequence iscomposed mainly of dark grey shales, and fossils were found in a single horizon where thin interlayeredbeds of fine reddish-brown micaceous sandstones appear where the environment of marinedeposition became more shallow. The age of the Lolén Formation is presently established on the basisof brachiopods, these being characteristic elements of the Malvinokaffric realm from the GondwanaLower Devonian (Emsian). The fossil plants are remarkably preserved given that they are in rocks thathave undergone intense deformation. The plants are identified as Haplostigma sp. and Haskinsia cf.H. colophylla, and suggest a Middle Devonian age (Givetian) for the fossil-bearing levels. Haskinsia,identified on the basis of leaf morphology, is the first well-delimited Middle Devonian lycopsid genusdescribed from Argentina, and the record from the most southerly palaeolatitude. During the MiddleDevonian, Haskinsia was distributed in tropical, warm temperate and high southern latitude, ?cooltemperate zones.