Geoscience Reference
In-Depth Information
Culebra Formation
Lithostratigraphy
The Culebra Formation is at least 250 m thick and consists of three members that in-
clude a lower unnamed member, the E.L. and an upper unnamed member (Figure 11).
The Culebra Formation contains a transgressive-regressive facies pattern, where the
lower member, the E.L. and the lower part of the upper member show a transgressive
pattern in which water depth deepened from intertidal at the base of the formation
to upper bathyal (Blacut and Kleinpell, 1969). The upper part of the upper member
shows a regressive pattern in which water depth shallowed from upper bathyal to in-
tertidal depths. These three members are described individually below.
Figure 11.
Scatter plot showing geologic age as a function of the 87Sr/86Sr ratio of fossil marine
shells from the La Boca Formation, Emperador Limestone and upper Culebra Formation. Error bars
represent standard error.
