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Book Cliffs Field Course Photo 2

Sequence stratigraphy of the Book Cliffs Panther Tongue Mbr at Gentile Wash, UT

LGC field course Day 2 (

The Panther was deposited as a fluvially-dominated delta during the lowstand phase of the Starpoint/Blackhawk stratigraphic sequence. The lower contact, though conformable with the Mancos Shale, forms the sequence boundary; whereas, the upper contact is the transgressive surface of the sequence and is overlain by another thin deposit of Mancos Shale. Three subdivisions are evident: 1) A basal interval of thinly interbedded sandstones dominated by Bouma sequences and lesser hummocky stratification, 2) A middle section of thin sandstones characterized by parallel laminations and hummocky stratification, and 3) A capping interval of lens-shaped sandstones that can be structureless, parallel laminated, trough cross bedded, or a mixture of the three. Sandstones in the capping portion may be amalgamated or can be separated by thin mudstones. The succession represents an upward transition from delta-front turbidites and storm beds at the base through shoreface deposits into channel-mouth bar and bay deposits. A highly burrowed transgressive lag, showing minimal erosion but containing scattered wood fragments and bivalve shells, caps the outcrop.

Panther Tongue - Gentile Wash.jpg