Dr. Alfred C. Lenz
Office: BGS 1000E
My ongoing research basically revolves around a
study of Wenlock to Lower Devonian graptolites of Arctic Canada. The
Silurian of the Arctic Islands is now internationally renowned for its
preservation of beautiful, three-dimensionally graptolites that may be
released from limestones through acid dissolution. The beautiful
preservation, and the fact that virtually the entire Silurian
intermediate-depth sequences yield such graptolites, results in this
being, arguably, the finest graptolite sequence in the world. In recent
years, I have focussed on the late Wenlock and Ludlow part of the
sequence and, in particular, on 1. the complex meshwork graptolites,
the retiolitids, and 2. the profound graptolite extinction event near
the end of the Wenlock in which 95% of all graptolites became extinct.
It now is clear that not only was the extinction a traumatic event in
the history of graptolites, but that in both the monograptid and
retiolitid groups, post-extinction graptolite morphologies were
distinctly different from those of the pre-extinction groups. Related
to similar-aged graptolite sequences elsewhere in the world and to
better understand the global nature of the extinction event, I have
been collaborating with foreign workers; for example, A.
Kozlowska-Dawidziuk and P. Štorch on a Barrandian sequence, Czech
Republic; J-C. Gutiérrez-Marco and J-M. Piçarra in Spain and Portugal;
and X. Chen, Y-N. Ni and Y-D. Zhang in China. Most recently, I have
broadened the Arctic studies to involve specialists in other sub
disciplines in an integrated study using several fossil groups, and
combining this with geochemical analyses of the same strata. A.
Kozlowska-Dawidziuk (Poland) joins me in studying the graptolites, P.
Noble (University of Nevada/Reno) is studying radiolarians, A. Soufiane
(Geological Survey of Canada, Quebec City) is studying palynomorphs,
C. Barnes (University of Victoria) is studying conodonts, and C,
Holmden (University of Saskatchewan) is carrying out geochemical
analyses, particularly of δ13C and δ18/16O. Results thus far are very promising, showing a strong δ13C
excursion at about the extinction boundary, comparable to those
elsewhere in the world. Our goal is now to extend the expanded and
integrated study from the late Wenlock to the top of the Silurian
basinal sequence. Ideally, the study should be able to compare faunal
and floral dynamics with environmental changes shown by geochemical and
sedimentological signatures and, from that, to better understand
Silurian history of the Arctic.
Lenz, A.C. and
Kozlowska-Dawidziuk, A. 2002. Late Wenlock and Early Ludlow graptolite
extinction, evolution and diversification: a reassessment. Studies in
Palaeozoic palaeontology and biostratigraphy in honour of C.H. Holland.
Special Papers in Palaeontology 67, p. 171-183.
J., Blodgett R. B., and Lenz, A.C. 2002. New early Devonian gastropods
from the families Crassimarginatidae (new family) and Scoliostomatidae
(new family), Royal Creek area, Yukon Territory, Canada. Journal of
Paleontology, 76: 246–255.
A.C. and Kozlowska-Dawidziuk, A. 2002. Upper Homerian (Upper Wenlock,
Silurian) graptolites from Arctic Canada. Journal of Paleontology,
A.C., Edwards, L.E. and Pratt, B.R. 2001. Note 64—Application for
revision of articles 48-54, biostratigraphic units, of the North
American Stratigraphic Code. American Association of Petroleum
Geologists Bulletin, 85:372-375.
R.B., Fryda, J., and Lenz, A.C. 2001. Semitubina yukonensis n. sp.,
first occurrence of this biogeographically distinctive old world realm
gastropod genus in the Lower Devonian of the western hemisphere.
Journal of Paleontology, 75:466-470.