Start |Author Index | View Uploaded Presentations | Meeting Information

North-Central Section (44th Annual) and South-Central Section (44th Annual) Joint Meeting (11–13 April 2010)

Paper No. 30
Presentation Time: 8:30 AM-12:00 PM

A POSSIBLE LATE PALEOZOIC NOVACULITE DEPOSIT IN THE PARANA BASIN, WITMARSUM PARANA STATE, BRAZIL


CARNICLE, Melissa M.1, GILBERTSON, Lea Ann1, ROCHA-CAMPOS, A.C.2 and COTTER, James F.P.3, (1)Geology, University of Minnesota Morris, 600 East 4th Street, Morris, MN 56267, (2)Instituto des Geosciências, Universidade de São Paulo, Sao Paulo, 05450-001, Brazil, (3)Geology Discipline, University of Minnesota, Morris, Morris, MN 56267, carn0083@morris.umn.edu

Novaculite is a specific type of cryptocrystalline quartz found in the Ouachita Mountains of Arkansas and Oklahoma and in the Marathon Uplift of Texas. Novaculite probably formed as a siliceous ooze in the Devonian Period and was metamorphosed into chert during the Ouachita Orogeny. Novaculite is a dense rock that is resistant to weathering. Native Americans mined Novaculite for sharpening stones, arrowheads and spear points and it is used commercially today as a whetstone.

A cryptocrystalline siliceous unit that resembles Novaculite was first found by Trosdtorf (2002) during mapping of Late Paleozoic glacial units in the southeastern Parana Basin near Witmarsum, Parana State, Brazil. The goal of this study is to compliment the efforts of researchers of the Instituto de Geociências, USP (e.g. Harabari; 2009 and Garcia; 2009) to determine if the Brazilian deposit is Novaculite sensu stricto. Fieldwork for this study consisted of detailed mapping Paleozoic units, description of possible Novaculite outcrops and sample collection. Lab work consisted of making thin sections and thin section analysis, XRD analysis and sample preparation for XRF analysis.

Field evidence suggests that the Brazil deposit is not Novaculite sensu stricto. At the time of deposition, the southern Parana basin was characterized by a high influx of terrestrial glacial and glacio-fluvial sediments. A siliceous ooze in contrast, only forms in sediment starved environments. Additionally, bedding and contact features indicate a rapid, contemporaneous accumulation of the siliceous unit and glacial units. Both U.S.P. research and this study indicate that an alternative model for the origin of the Parana Basin siliceous unit may be volcanic tephra. However, a specific volcanic source is difficult to identify even though tephra are known throughout the Parana Basin. Geochemical analysis should provide additional insight on the origin of this unique deposit.

Research for this study was funded by a grant from the N.S.F.- S.T.E.P. Program (NSF-DUE-0653063)

Session No. 18--Booth# 30

T33. Undergraduate Research (Posters)
Monday, 12 April 2010: 8:30 AM-12:00 PM
Taneycomo A (Branson Convention Center)
Geological Society of America Abstracts with Programs. Vol. 42, No. 2, p.63
© Copyright 2010 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.
Back to: T33. Undergraduate Research (Posters)
<< Previous Abstract | Next Abstract >>