Integration of Palynology and Sequence Stratigraphy
in the Analysis of Miocene Siliciclastic Aquifers,
McLaughlin, Peter P.1 (1)
Ground water is an important natural
resource in the coastal plain of Delaware, where it comprises nearly the entire
water supply. Miocene confined aquifers are an important part of this resource
in central and southern
The lower to middle Miocene section of
the study area is characterized by alternating sands and muds.
These represent a stack of transgressive and highstand systems tracts deposited in shallow- to marginal-marine
environments. Aquifers are typically developed in the nearshore
sand facies at the top of the sequences. Four
aquifers are targets: the Cheswold, Federalsburg,
Frederica, and
Palynology is a tool that can help
resolve correlation issues in this succession. The flora is dominated by Quercus, with common Carya
and Pinus, and several subtropical to tropical “exotic” taxa that do not presently live in or near the study area. The
assemblages reflect subtropically influenced
warm-temperate environments with a decrease in subtropical influences through
time. Subtle stratigraphic changes are noted in the
assemblages. Lower Miocene assemblages are mostly composed of temperate and
warm-temperate arboreal forms, commonly with greater abundances of taxodiaceous pollen than in higher intervals. Lower Miocene
exotics include common Engelhardia-type pollen
and scattered Podocarpus. Middle Miocene
assemblages are similar but have fewer exotics; Pinus
is commonly more abundant than in lower intervals. Engelhardia-type
pollen is the most common exotic in the middle Miocene but generally decreases
upward, and Pterocarya, Podocarpus,
and Symplocos are present.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California