Research PDB-03 serves as a type log
through the Delaware Basin section.
discussion is for the purpose of setting the context for understanding
the relationship of the Midland Basin salts to the Delaware
Basin adjacent to the study area. More detailed descriptions
are presented elsewhere (for example, Adams, 1944; Anderson
and others, 1972; Snider, 1966; Lowenstein, 1988; and Hovorka,
1990). The upper Guadalupian section is composed of the Bell
Canyon Formation, capped by the Lamar limestone, a finely
laminated, organic-rich, silty limestone deposited prior to
evaporite precipitation. The Bell Canyon Formation is the
deep-water basinal equivalent of the Seven Rivers, Yates,
and Tansill Formations on the Platform (Garber and others,
1989). Because of its high gamma-ray-log response and sharp
contact with overlying Castile Anhydrite I, this contact serves
as an excellent stratigraphic marker.
two regionally traceable anhydrite-dolomite beds of the Rustler
Formation are tentatively correlated with the two anhydrite-dolomite
beds of the Alibates Formation, and the siliciclastics of
the Dewey Lake with upper Rustler siliciclastics. In the Delaware
Basin, insoluble residue is commonly included within the lower
clastic unit of the Rustler Formation (Holt and Powers, 1987).
Additional stratigraphic complexity observed elsewhere in
the Rustler Formation (Holt and Powers, 1987) may be important
for resolving the evolution of this part of the section but
is outside the scope of this study.
Salado Formation in the Delaware Basin was examined in the
Gulf Research PDB-03 core has a log response similar to the
Salado Formation of
the Midland Basin. Cycles defined by anhydrite with
or without polyhalite replacement define the base of cycles.
Thick relatively pure halite (minor mud, polyhalite, and anhydrite)
make up the upper part of cycles.
study, I used a unit tentatively correlated with the lower
Salado MB 134 of Snider (1966) as a genetic break between
the Salado and the Castile Formations. This unit was selected
because, during my study of the PDB-03 core from Pinial Dome
in Loving County,