Geological Society of America

T103 Zircon and Beyond: Quantitative Methods for Characterizing Provenance in Modern and Ancient Sediment Routing Systems (Posters)

Monday, 23 September 2019
9:00 AM - 6:30 PM
Hall AB, North Building

PROVENANCE ANALYSIS OF SEDIMENTS RELATED TO THE CAMBRIAN ROSS OROGEN, ANTARCTICA: LASER-INDUCED BREAKDOWN SPECTROSCOPY ANALYSIS OF DETRITAL TOURMALINE

Paper number: T103-4
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Jenelle A. Hansen Presenting Author
New Mexico State University, Las Cruces, NM
Nancy McMillan
New Mexico State University, Las Cruces, NM
Barbara Dutrow
Louisiana State UnivDept Geology & Geophysics, Baton Rouge, LA
Cole Mount
New Mexico State University, Las Cruces, NM
Darrell J. Henry
Louisiana State University, Baton Rouge, LA
John Goodge
University of Minnesota, Duluth, MN

Abstract

Tourmaline (tur) is a complex borosilicate mineral with the ability to incorporate a large number of chemical elements that reflect its host, which makes it ideal for provenance studies. It is sufficiently durable to persist through erosional, depositional and metamorphic episodes, while retaining the chemical signature of its lithological source. The most common source lithologies for tourmaline comprise six major groups and are modeled in this work based on elemental fingerprints within ca. 250 samples with known host-rocks by applying the multivariate techniques of principal component analysis (PCA) and partial least squares regression (PLSR) to Laser-Induced Breakdown Spectroscopy (LIBS) spectra. These categories include: lithium-cesium-tantalum-rich pegmatites (LCT), niobium-yttrium-fluorine-rich pegmatites (NYF), metacarbonate rocks, pelitic metamorphic rocks, silicic igneous rocks, and hydrothermal deposits. LIBS spectra of detrital tur grains from Neoproterozoic passive-margin sandstones and Cambrian-Ordovician syn- and late-tectonic Ross Orogen sandstones from East Antarctica were sorted into the six major source-lithology categories using PLSR and cluster analysis was used to define compositional groups within each category. Passive-margin sediments contain tur from NYF, hydrothermal, and silicic igneous sources. Some of these populations persist from the passive margin stage through the syn- and late-tectonic stages of the Ross Orogen; new populations of NYF, hydrothermal and silicic igneous tur as well as tur from LCT, metapelitic, and metacarbonate sources also occur in the syn- and late-tectonic sediments. Consistent with detrital zircon geochronology, it is possible that the populations of syn- and late-tectonic detrital tur shared by the passive-margin sediments were either recycled from deformed passive-margin sedimentary rocks or derived from similar sources during tectonic exhumation. New tur sources were produced by igneous, metamorphic, and hydrothermal processes during the Ross Orogen. This study demonstrates that provenance studies based on the chemical analysis of detrital tur with LIBS and multivariate analysis is viable and can discriminate changing source patterns.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-339295

© Copyright 2019 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.