New Zealand Journal of Geology and Geophysics abstracts
Carboniferous conodonts from Rakaia Terrane, East Otago, New Zealand
P. Jane Forsyth
GNS Science
Private Bag 1930
Dunedin, New Zealand
Gregory M. Martin
Formerly Department of Geology
University of Otago
PO Box 56
Dunedin, New Zealand
Hamish J. Campbell
John E. Simes
GNS Science
PO Box 30368
Lower Hutt, New Zealand
Robert S. Nicoll
Department of Earth and Marine Sciences
Australian National University
Canberra, ACT, Australia 0200
Abstract Conodonts of Late Carboniferous
(Pennsylvanian) age have been recovered from marble within a 100 m
thick sequence of pure and impure marble, hematitic and chloritic
slate, and metachert in Torlesse Supergroup semischist of the Rakaia
Terrane. This sequence is exposed near Conical Peak in the Kakanui
Mountains, Otago. Bands of marble contain microscopic metavolcanic
clasts, quartz grains, and conodont elements in a groundmass of
recrystallised calcite. The conodonts include at least three genera: Idiognathodus, Streptognathodus, and Gondolella, which together suggest an age of mid-Middle Pennsylvanian to latest Pennsylvanian. The
red and green slate represents metamorphosed volcaniclastic beds, and
grey slate represents background deposition. Bedding indicators, where
present, are subparallel to the plane of cleavage development. No
facing directions are recognised. Sandstone and mudstone have been
metamorphosed to pumpellyite-bearing semischist of textural zone IIA.
The calcareous, siliceous, and metavolcanic sedimentary rocks are
interpreted as deep-sea turbidites, sourced from a topographic high,
probably a seamount. Associated turbiditic sandstone and mudstone are
of continental provenance.
Keywords conodonts; Idiognathodus; Streptognathodus; Gondolella; Late Carboniferous;
Pennsylvanian; Blue Mountain Formation; Rakaia Terrane; Torlesse
Supergroup; semischist; marble; Kakanui Mountains; Blue Mountains; Kakahu Marble; Otago; New Zealand
G05043; Received 25 August 2005; accepted 30 May 2006; Online publication date 26 July 2006
New Zealand Journal of Geology & Geophysics, 2006, Vol. 49: 329–336
0028–8306/06/4903–0000 © The Royal Society of New Zealand 2006
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