QUERECUAL, Formation

CRETACEOUS (Turonian)

State of Anzoátegui, Venezuela

Author of name: H. D. Hedberg, 1937.

Original reference: H. D. Hedberg, 1937a, p. 242.

Original description: ibid.

Hedberg (1937a, p. 242) originally named and described the Querecual formation as the lower part of the Guayuta group. The formation consists of a sequence of hard, black, thin-bedded and laminated carbonaceous limestones and calcareous shale with characteristic discoidal limestone concretions, and having common layers of black cherty limestone in the upper part. As type section, he designated the Río Querecual southeast of Bergantín from a point about 250 meters upstream from Paso Hediondo to a point about 600 meters downstream from Paso Hediondo where it is about 2,400 feet thick and in conformable stratigraphic relation with the underlying Bergantín beds (including the Boquerón-Majagual formation of Rod and Maync, 1954, p. 251-252), and the overlying San Antonio formation. Pelagic foraminifera (Globigerina, Globotruncana, Gümbelina) give the limestones a marked character in thin section. Although megafossils are scarce in the type section, the occurrence of amonites and Inoceramus elsewhere, establish an approximate Turonian age for this formation which correlates with the La Luna formation of western Venezuela.

Hedberg (1937b, p. 1990) expanded upon his original description and later, Hedberg and Pyre (1944, p. 10) discussing the stratigraphic relations of the Querecual formation, say: "... The contact with the underlying Chimana..." (Boquerón-Majagual formation of Rod and Maync, 1954) "...formation is sharp (fault contact on Río Querecual), but the two formations are apparently conformable. . . " The contact with the overlying San Antonio formation is placed at the base of the first more or less continuous sandstone. Hedberg (1950, p. 1191) states that megafossils indicate the age of the Querecual formation to be no older than Turonian. Such is corroborated by the Cenomanian age of the underlying Boquerón formation of Rod and Maync (1954, p. 279), which formation comprises the same beds as those previously referred to by Hedberg and Pyre (1944, p. 9) as the transition zone between the Chimana and the Querecual formations. The Querecual formation has a wide geographic extent throughout the Serranía del Interior.

Wm. K MacFarquhar