PAUJI, Formation

TERTIARY (upper middle Eocene-upper Eocene)

State of Zulia, Venezuela

Author of name: R. Arnold, 1912-1916 (private reports) (?).

Original reference: R. A. Liddle, 1928, p. 242.

Original description: ibid.

Liddle (1928, p. 242) who first published the name Paují shale stated that probably the name was first applied by Arnold in private reports.

The type section is on the Río Paují in the district of Baralt, State of Zulia, where the stream emerges from the Serranía Trujillo. According to Tash (1938, p. 164-167), the term Paují shale was used by Dagenais as early as 1914, possibly before Arnold. The Paují formation consists essentially of a thick shale series. The strata vary from practically pure black, massive shales, with very little sand content, to thin-bedded sandy shales, platy sandstones and thin limestone layers. The laminated sandy shales, platy sandstones and limestone lenses are chiefly confined to the upper portion of the formation. The shaly part of the original formation is the Paují shale of present definition, the sandy and limy beds the Mene Grande series (see Mene Grande formation). According to Tash (1938, p. 166), the Paují shale consists of an essentially massive, dark-gray to black, slightly sandy and pyritic shale with frequent nodules of limy, siliceous, or pyritic material. In general, there are no sandstones in the true Paují formation until the basal transition zone is reached, just above the Misoa-Trujillo formation. Drilling however, has shown the presence of a hard, rather quarzitic sandstone, 62 feet thick, in the upper portion of the middle part of the Paují formation. This sandstone appears to have only a very limited lateral extent.

Sutton (1946, p. 1670) states that the Paují formation originally included all upper Eocene sediments lying above the Misoa formation in the general area of the Mene Grande oil field. Later, observers noted that a three-fold division could be established to comprise a basal transition zone composed almost entirely of shale, and an upper zone of interbedded sandstones, reef limestones, and shale. Still later, according to Sutton the upper zone was removed from the Paují formation and named Mene Grande formation. Sutton called the lower zone, lower Paují; the middle zone, Upper Paují, and the upper zone, Mene Grande formation.

The Paují formation is conformable with the Misoa formation below, and apparently conformable but probably disconformable with the Mene Grande formation above.

According to the Staff of the Caribbean Petroleum Co. (1948, p. 567) the Paují formation (without the Mene Grande formation) in the Mene Grande field, has a thickness of about 2,000 feet; the total thickness is difficult to determine because of the Miocene unconformity and structural complications. Sutton (1946, p. 1670) gives a thickness for the Upper Paují of 5,395 feet being the interval between the top of the Potreritos and the surface in the well Pica-Pica-1 in the Bolívar district. At least 400 feet of Lower Paují has been penetrated in the Mene Grande field without reaching the base of the formation and the Upper Paují in this field has a thickness of 2500 feet according to Tash (1938, p. 167). On the Río Caús in southwestern Trujillo, the Lower Paují measures 246 feet and near El Marfil on the Los Baños anticline the Upper Paují is at least 3641 feet thick.

The Paují formation crops out along the western flank of the Serranía de Trujillo and Cerro Misoa, and is found in wells in the southern Bachaquero field and in the Mene Grande field. In Trujillo, the Paují formation is prominent on the Escuque and Los Baños anticlines and extends along the front of the Mérida Andes southwest past the Río Caús into the northern corner of the State of Mérida.

The age, according to Sutton (1946, p. 1671), is upper Eocene. A prolific marine fauna of smaller foraminifera is described by Nuttall (1935, p. 121-131). The reef limestones of the Paují on the Río San Pedro and Río Caús contain larger foraminifera. According to Van Raadshooven (1951, p. 482) these faunas show distinct differences from the typical upper Eocene faunas and contain species, which point strongly to an upper middle Eocene age.

The Río Raya shale of Garner (1926, p. 681) and the Los Baños shale of Garner (1926, p. 681) are obsolete names for the Paují, considered to be Oligocene by Garner. According to Sutton (1946 p. 1672) the Río Caús formation of Liddle (1928, p. 238-239) is the equivalent of the somewhat thicker orbitoidal limestone in the upper part of the Lower Paují in the section along the Río Caús in southwest Trujillo. Both the San Pedro "formation" and the Río Caús "formation" should rank as local reef limestone members of the Paují formation. For other correlatives, see Sutton (1946, p. 1672). The "Upper Micaceous Sandstone" of the Bolívar coastfields corresponds approximately to the Paují formation of the Mene Grande area, according to the Staff of Caribbean Petroleum Co. (1948, p. 537).

W. A. Mohler

MENE GRANDE, Formation

TERTIARY (upper Eocene)

State of Zulia, Venezuela

Author of name: R. Arnold, 1915 (private report).

Original reference: G. E. Tash, 1937, p. 165.

Original description: ibid.

The name Mene Grande series has first been used by Arnold, geologist of Caribbean Petroleum Co. in private reports. Tash (1937, p. 165) gives the first full description quoting directly from Arnold's report of 1915. The name is taken from the Mene Grande oilfield, in the district of Baralt, southeastern Zulia, where the best section is found in a small quebrada which originates near the north end of the Mene Grande oil seep and runs west toward the lake. According to Tash (1937, p. 165-166) the term Mene Grande series was used for the upper member of the Paují formation which is described as follows (Dagenais, quoted by Tash): the upper part of the Paují shale is made up of a succession of thinly bedded, dark gray sandstone and black shale. Occasional reefs and lenses of orbitoidal limestone are in places intercalated with the sandstone. The approximate thickness of this sandy phase of the Paují is about 328 feet. According to Tash, the Mene Grande varies in thickness from 75 to 475 meters. The Mene Grande formation rests on the Paují formation with apparent conformity, it is covered discordantly by the nonmarine Miocene Isnotú formation, according to Sutton (1946, p. 1685).

Sutton (1946, p. 1685) uses the name Mene Grande formation, as well as the Staff of Caribbean Petroleum Co. (1948, p. 569) and Liddle (1946, p. 376).

The Mene Grande formation, like the Paují formation, is upper Eocene in age, and both formations have many foraminiferal species in common. The Mene Grande can be readily distinguished by the presence of certain species of larger foraminifera and species of Bathysiphon, Bulimina, Cassidulina, Cibicides, Clavulina, Dorothia, Globigerina, Spiroplectammina, Textularia, Trochammina, Uvigerina, Verneuilina and Valvulina, according to Tash (1937, p. 170). For fossil lists of larger foraminifera determined by various paleontologists, see Sutton (1946, p. 1686).

The Mene Grande formation crops out near the Mene Grande oilfield and extends from the Rio San Pedro northward as far as the Santa Bárbara-Los Barrosos road. According to the Staff of Caribbean Petroleum Co. (1948, p. 569), the thickness of the Mene Grande formation observed in the Mene Grande field ranges from almost nothing to 120 feet, but east of the field, in the Raya syncline, the total thickness is estimated to be about 2150 feet.

The Mene Grande formation of Garner (1926, p. 682) consists of alternating massive, brown and, red, coarse, soft sandstones and white to brown ferruginous clays, outcropping in the hills immediately north of Mene Grande.

The age indicated by Garner is Miocene and it is possible that these sediments are post-Eocene indeed.

W. A. Mohler