SEBASTOPOL, Basal Complex

See SEBASTOPOL, "Granite"

SEBASTOPOL, "Granite"

MESOZOIC (?) or older

Distrito Federal, Venezuela

Authors of name: S. E. Aguerrevere and G. Zuloaga, 1937.

Original reference: S. E. Aguerrevere and G. Zuloaga, 1937, front p. 12.

Original description: ibid.

S. E. Aguerrevere and G. Zuloaga (1937, Geologic column, front p. 12) were first to name the Sebastopol granite, describing it as a "granite... containing quartz and specular hematite veins; mineralized joints with adularia, hematite and quartz". In the same column, the granite unconformably underlies the Las Brisas basal conglomerate of the Caracas "series". In the text, the authors (p. 12) refer to that unit as an old igneous complex.

The same authors (1938, p. 284) established the type locality at the Km. 20 of the Caracas-Los Teques road, changed the original name to Sebastopol Basal Complex and enlarged its description in the following way: "gneissic granite with greenish biotite; contains thick quartz veins of specular hematite and adularia in the joints; also chloritic schists and schistous zones". They pointed out that the unit constitutes locally, the nucleous of the Cordillera de la Costa.

Dengo (1951, p. 50-53) refers to the same unit under the name "granitic ortho-gneiss" and reasserts its stratigraphic position as basement of the Cordillera de la Costa metamorphic sequence. Dengo describes it as a rock with well developed "foliation" consisting of light and dark bands; rather uniform mineralogic composition made-up of quartz, orthoclase, microcline, plagioclase, muscovite and biotite. He gives also a specified description about textural and mineralogic variations of the ortho-gneiss.

Smith (1952, p. 347) suggests the possibility of a correlation between the Sebastopol Basal Complex and the granite outcrops at El Baul (see Mogote Granite).

The outcrops of the Sebastopol granitic orthogneiss are scarce. They are found at the San Pedro River (site called Sebastopol) and at the Km. 26, approximately, of the Caracas-Los Teques road; in the El Valle River (Los Lechosos site, north of the dam ot La Mariposa); in the roads from Maracay to Ocumare de la Costa and from Maracay to Choroní.

The Sebastopol Complex constitutes the basement of the Caracas group and therefore of the Caribbean Series in the Cordillera de la Costa, as it is clearly indicated by the granite and quartz fragments found in a basal conglomerate of the Las Brisas formation, at the type-locality of the same unit, as well as at the Kms. 18-20 and 24-25 of the Caracas-Los Teques road.

S. E. Aguerrevere and J. M. Sellier de Civrieux