GARRAPATA, Formation

See ARRAYANES, Group

ARRAYANES, Group

UPPER CRETACEOUS

State Aragua, Venezuela

Author of name: E. Mencher, 1942.

Original reference: E. Mencher et al., 1951, p. 13.

Original description: ibid.

E. Mencher et al. (1951, p. 13), suggested the use of the term Arrayanes formation in reference to a sedimentary-volcanic series of conglomerates, coarse to fine-grained graywacke sandstones and quartzites, and silty shales, all of a general dark-gray to black color, interbedded with flows of basaltic to andesitic composition, tuffs and agglomerates, in the correlation chart accompanying the report, the Arrayanes formation is listed as occurring in the piedemont zone of northcentral Venezuela. No other mention is made of the locality of outcrop. It is also mentioned that the total thickness of the formation is not known and that it is so broken by folding and faulting that more study is required before the details of deposition can be worked out.

Additional reference is made to the formation by Smith (1953, p. 61) who mentioned that G. Pardo, in 1942, while mapping in the vicinity of San Sebastián, State of Aragua, for the University of Caracas, discovered a Cretaceous ammonite in unmetamorphosed Arrayanes rocks. Careful study by Pardo and E. Mencher showed that it had not been reworked. This ammonite has been identified as Peroniceras cf. moureti De Grossouvre by A. A. Olsson, and given an early Senonian age. Other identifications confine its age to the Coniacian. H. H. Hess, in a heavy-mineral study of the matrix surrounding the fossil, noted the presence of an abundance of the same peculiar pyroxene, characteristic of the Tiara volcanic sequence, that has a pronounced, almost micaceous, parting. In addition, chromite was present, undoubtedly originating in the serpentine rocks intrusive into the Paracotos formation (Smith, 1953, p. 61).

E. Mencher et al., 1953, p.. 775 (Correlation chart) rise the Arrayanes to group, giving it an age from the Coniacian to the Danian included. H. H. Renz, 1955, p. 52, includes his Escorzonera formation in the upper part of the group. Renz proposes the name Garrapata formation for the lower part of the Arrayanes group.

H. Alberding