- Philip Heckel
- Professor of Geology
- University of Iowa
PRINCIPAL RESEARCH ORIENTATION:
I have been carrying out (and advising projects in) detailed
geographic, stratigraphic, paleontologic and petrographic
investigations of sedimentary rock units in order to determine
the nature and distribution of different rock types and to
delineate both sedimentary features such as reefs, channels,
deltas, shorelines, etc., and diagenetic features resulting
from ancient soil profiles, water tables, etc., which together
control the distribution of rock types, mineralization patterns,
and fluid migration routes, some having economic significance.
The results of these studies have been shedding new light
on basic patterns of rock distribution vertically and laterally
across the Midcontinent sedimentary basin of North America.
This has allowed identification of probable factors responsible
for these patterns, and development of sedimentary models
that integrate and summarize the patterns and factors determined
to be responsible. My New York and Midcontinent projects and
invited papers for various symposia have been oriented toward
these ends. The paleoclimatic world reconstructions I made
for the 1978 Bristol Devonian symposium, helped me ultimately
to develop a sedimentary model involving changes in ancient
oceanic circulation patterns for the Midcontinent Pennsylvanian
sea. This ancient sea extended from Oklahoma through Kansas
and Missouri to Iowa and Nebraska about 300 million years
ago, and its deposits have been the major focus of my research
interest since 1966. More recently, I constructed a sea level
curve for this area through a span of about 10 million years,
which I presented at an invited symposium on cyclic sedimentation
at Princeton University in May 1985. I also showed that the
periodicity of this curve is similar to the frequency of sea-level
changes of similar magnitude resulting from periodic ice cap
formation and melting occurring for the last few million years
of earth history. This strongly suggests linkage of the ancient
Pennsylvanian sea-level changes to the continental glaciation
known to have occurred then in the southern hemisphere. Since
then, with the help of several paleontologists, I have begun
to correlate these ancient glacial sea-level changes recognized
in the Midcontinent with those now being recognized in sequences
of the same age in Texas, Illinois, and the Appalachians,
as the more distant extents of the ancient sea, such that
we will now be able to segregate and analyze the influence
of tectonic (mountain-building) forces on ancient sea-level
changes separately from the glacial control already delineated.
Most recently, with my 1993 selection to membership in the
Project 5 working group of the Subcommission on Carboniferous
Stratigraphy (SCCS) of the International Commission on Stratigraphy
(ICS) of the International Union of Geological Sciences and
my 1996 election to voting membership in the SCCS itself,
I have become involved in evaluating the suitability of several
well-studied rock successions of the same age in different
parts of the world as candidates for boundary stratotypes,
which will be used to define particular "instants" in geologic
time on a global scale.
|
