Facies and Architecture of the
Chimney
Rock
Member,
Rock
Springs
An outcrop study, a core well drilled through the outcrop,
and well logs along the northern margin of the
Rock
Springs Uplift of
southwestern
Rock
Member
(basal clastic wedge) of the
Rock
Springs Formation.
The Chimney
Rock
Member is comprised of three facies
associations. The lowermost sections of the Chimney
Rock
Member are
representative of deposition within a wave-dominated shoreface,
with the overlying medial parts of the section consisting of incised-valley
deposits (wave-dominated estuarine and tidal deposits). These two sections of
the Chimney
Rock
Member are separated by a significant erosion surface, a
sequence boundary that marks a relative fall in sea-level. The upper reaches of
the Chimney
Rock
Member consist of a mixed strandplain
and coastal plain succession. A throughgoing flooding
surface and transgressive lag (likely TSE) separates
the incised valley fill from the overlying mixed strandplain
and coastal plain deposits.