UCHIRITO, Formation

TERTIARY (predominantly upper Oligocene)

State of Anzoátegui, Venezuela

Author of name: A. Krumholz, 1941 (private report).

Original reference: H. D. Hedberg and A. Pyre, 1944, p. 22.

Original description: ibid.

The Uchirito member of the Santa Inés formation or group was named by Krumholz (1941, private report) and first published by Hedberg and Pyre (1944, p. 22) to designate what Hedberg (1937, p. 2009) had previously described as the basal part of the Santa Inés formation. It consists of mottled, gritty, calcareously-cemented sandstones and chert pebble conglomerates, in part forming the prominent Uchirito ridge, with intervals of gray, fissile, silty, foraminiferal shales in its lower part. The unit thickens westward at the expense of the Carapita shale, merging with the Capaya formation to form the Capiricual formation in the Barcelona area. It is assigned a lower Miocene age (Hedberg and Pyre, 1944, fig. 4). The Uchirito member conformably overlies the Carapita shale and is conformably overlain by the Revoltijo member.

Hedberg (1950, p. 1201-1202) raised the unit to formation rank as part ot the Santa Inés group. In its uppermost part it is probably the shallowwater equivalent of the basal Quiamare formation farther west. To the east, it apparently grades into the shallow-water marine "Orégano formation", and may eventually grade into a part of the Carapita shale formation encountered in wells of north-central Monagas.

The Uchirito formation outcrops for a distance of some 45 kilometers in northeastern Anzoátegui. Recent paleontological evidence indicates that it is predominantly of upper Oligocene age.

Cecily Petzall