CUMAREBO LIMESTONE, Member

TERTIARY (upper middle Miocene)

State of Falcón, Venezuela

Author of name: R. A. Liddle, 1928.

Original reference: R A. Liddle, 1928, p. 343.

See CAUJARAO, Formation.

CAUJARAO, Formation

TERTIARY (upper middle Miocene)

State of Falcón, Venezuela

Author of name: C. Wiedenmayer, 1937.

Original reference: C. Wiedenmayer, 1937, p. 69.

Original description: ibid.

R. Arnold (1921, private report) provisionally named this formation the "Damsite" limestone (Arnold´s quotes).

Hodson (1926, p. 173) wrote the following original published description of the Damsite: "Damsite series: Chiefly limestones, clays and soft sandstones. Type locality Damsite at Caujarao, south of Coro, on Río Coro, District of Miranda, State of Falcón".

Liddle (1928, p. 293 - 303) changed the name to Damsite Formation and amplified the description by stating that the clays and clay shales are predominant in amount over the massive limestones which are more prominent topographically, that the greatest thickness of the formation does not exseed 3,000 feet, and that there is a complete and gradational transition from the Socorro Formation upward through the Damsite Formation and into the La Vela beds. He assigned the Damsite to the middle and upper middle Miocene and listed many fossils. He included the Sabaneta limestone (Garner, 1926, p. 683) in the Damsite formation.

Senn (1936, p. 80-84) listed many fossils from the Damsite formation, agreed on their middle Miocene age and gave the thickness of the formation as 1,000 to 1,500 meters. He included in the Damsite Formation of the Cumarebo region the Dividive limestone and the "Capadare limestone" (Cumarebo limestone of later authors), and he extended the Damsite Formation into eastern Falcón to include the upper Bachacal beds, the Miogypsina limestone, the Intermediate beds and the Capadare limestone (also called Clypeaster limestone).

Wiedenmayer (1937, p. 69) employed the name Caujarao formation for the first time. He assigned it to the middle Miocene and described it as 1,625 meters of marine (neritic and estuarine) deposits, among which are fossiliferous limestones, laminate clays, marls, soft sandstones and calcareous fossiliferous sandstones. The type locality was given as Quebrada Cujima and Caujarao.

González de Juana (1937, p. 190, 192-195) was the first to indicate that the Damsite formation and the Caujarao formation are synonymous terms. He called the name Damsite meaningless and apparently preferred the name Caujarao. He placed the Corocorote limestones in the lower part of the La Vela formation, the Cumarebo limestone at the top of the Caujarao formation, and the Dividive limestone at the base of Caujarao (p. 195) or at the top of the Socorro formation (pl. 6 opp. p. 202). He made the only published reference to the Mataruca and Rim Rock limestones, local members of the Caujarao to the south and southwest of the La Vela structure.

Liddle (1946, p. 466-477, correlation chart) accepted the name Caujarao formation and included in it the Sabaneta limestone, the Urumaco formation, the Capadare formation, the Pueblo Cumarebo formation, the Agüide limestone, the Miogypsina limestone, the Dividive limestone, the "Ala" clays and the Intermediate beds.

Payne (1951, p. 1854, 1859-1860) assigned to the middle Miocene the entire Caujarao formation of the Cumarebo area and included in it the Portachuelo member, the Cumarebo limestone member, the Corocorote limestone member and the Turupía clay member. The Dividive limestone and its lateral equivalent, the San Francisco sand, were considered to be the top members of the Mosquito formation. The Turupía clay member (Santa Rita clay of company reports) contained the Alc foraminiferal fauna of Senn and the Portachuelo member contained his Ala foraminiferal fauna. Sands 1-14 of the Cumarebo well sections were placed in the Portachuelo member and sand 15 was equated with the San Francisco sand.

The names "Damsite" limestone, "Damsite" series and "Damsite" formation are all considered to be invalid because of their nongeographic derivation. The name Caujarao formation is generally accepted as their substitute. The type locality is the section along the Rio Coro at the village of Caujarao, District of Miranda, north-central Falcón. Here the Caujarao formation is composed of nearly vertical, hard, massive, fossiliferous limestones, the thickest of which provides the site of the old Spanish dam, clays, marls, soft sandstones and calcareous fossiliferous sandstones. These deposits are all neritic. The upper middle Miocene Caujarao formation is conformable and transitional with the uppermost Oligocene to lower middle Miocene Socorro formation below and with either the upper Miocene Codore or "la Vela" above. In the Cumarebo area, to the east there is a questionable unconformity between the top of the Caujarao and the base of the upper Miocene El Veral.

Present practice is to consider the Urumaco formation lithologically distinct from, but laterally equivalent to the Caujarao formation. The Sabaneta limestone forms part of the Urumaco formation. Dince the publication of Payne´s paper, it has been learned from surface geological mapping that the contact between the type Caujarao and the subjacent Socorro on the Río Coro is equivalent to the top of Sand 1 in Cumarebo field. Consequently, it became necessary to remove from the Caujarao that portion of the Portachuelo member lying below the top of Sand 1 and to place it in the Socorro formation along with the Dividive limestone and the San Francisco sand. Since the section from the top of sand 1 down to the top of sand 15 constitutes the major portion of the Portachuelo member of Payne, it retains the name, and this restricted Portachuelo member becomes the top member of the Socorro formation. The upper part of Payne´s Portachuelo member, consisting of clay shales between the top of sand 1 and the base of the Cumarebo limestone, was given the new hitherto unpublished name, Cumarebito member, the bottom member of the restricted Caujarao formation. The type locality is the hamlet of Cumarebito near the southwest end of the Cumarebo field. Where the Cumarebo limestone is absent, the top of the Cumarebito member may extend up to the base of the Corocorote limestone or to that of the Turupía clay. The Cumarebo limestone member is a long, relatively narrow, algal reef, dislocated by faulting, overlying the Cumarebito shale member and underlying the Corocorote limestone member. The Pueblo Cumarebo formation and the "Capadare limestone" of the Cumarebo field are synonyms of the Cumarebo limestone member of the Caujarao formation. The Maturaca and Rim Rock limestones are the thin northern fringes of the reef near the La Vela structure. The Cumarebo limestone member is 0-300 feet in thickness. The type locality is south of Pueblo Cumarebo on Cerro de los Indios. The Corocorote limestone member is typically developed only where the Cumarebo reef limestone is present, for it is composed of the recemented algal debris from the reef and limonite, frequently in the form of pellets. Although the contact between the Corocorote and the underlying Cumarebo appears to be unconformable, it is probable that the two members were deposited to some extent simultaneously. The type locality is Corocorote Bajo, a hill near the southwest end of Cumarebo field. To the north the Corocorote limestone member is laterally replaced by the Turupía clay member (the "Santa Rita clay" of early company reports). The type locality of the Turupía clay is north of the small village of Turupía 3 kilometers east of the northeast end of Cumarebo field. The type locality of the "Santa Rita clay" is just north of the northeast end of Cumarebo field. The name "Santa Rita clay" was discarded and replaced by the name Turupía clay because it is a homonym of the Santa Rita conglomerate of Senn (1935, p. 60-62). The Turupía clay is about 1,850 feet thick, rests conformably upon the Cumarebito clay shale member or upon the Corocorote member, and lies with questionable unconformity beneath the El Veral formation of the upper Miocene. The type Capadare limestone, the Clypeaster limestone, the Intermediate beds, the Miogypsina limestone, the upper Bachacal beds, the Agüide clays the Jacura limestone, the Guaidima limestone, the Agüide limestone and the "Ala" clays all are situated in eastern Falcón beyond the outcrop area of the Caujarao formation and for various reasons should not be included in it. The Caujarao formation occurs only in north-central Falcón, or, more specifically, in the eastern part of the District of Miranda, the northern part of the District of Colina and the northwestern part of the District of Zamora.

A. N. Dusenbury, Jr