The provenance potential of detrital monazite was investigated by in situ measurement of 232Th-208Pb dates of grains isolated from six Middle Carboniferous-Permian sandstones from the Appalachian foreland basin. Provenance assessment of these units was previously investigated by measuring U-Pb crystallization ages of detrital zircon (Thomas et al., 2004; Becker et al., 2005, 2006). Approximately 90% of the detrital zircon ages record Mesoproterozoic or older ages, with only 10% recording the three major pulses of tectonism (Taconian, Acadian and Alleghanian) that are the hallmark of the Appalachian Orogen. 232Th-208Pb ages of detrital monazite, however, strongly record the complex phases of Paleozoic orogenesis. Nearly 65% of the ages record Paleozoic events, while 35% record Neoproterozoic or older ages. In several of the analyzed sandstones, detrital monazite ages record Paleozoic orogenic events that are completely missed by detrital zircon ages, demonstrating that monazite ages more accurately reflect the character of the sediment source rocks. The inferred maximum age of sediment deposition, as determined by the youngest monazite grains, is ~550Ma younger for two of the analyzed sandstones compared to depositional constraints based on the youngest detrital zircon. The different physical properties and petrogenesis of zircon and monazite are interpreted to be factors for the dramatic differences in sediment provenance information provided by each mineral. The results from this study have important implications for determining sediment provenance, constraining maximum age of sediment deposition, and developing robust regional tectonic models.
|Number of pages||10|
|Journal||Earth and Planetary Science Letters|
|State||Published - Oct 15 2011|
Bibliographical noteFunding Information:
This research was supported by the National Science Foundation (EAR #0635643 and EAR #0635688 ). All histograms were made using the Microsoft Excel macro AgeDisplay developed by Keith Sircombe ( Sircombe, 2003 ). We thank Axel Schmitt for extremely helpful guidance in collecting data at the UCLA SIMS facility. Grants from the NSF Instrumentation and Facilities Program, Division of Earth Sciences , supported the UCLA ion microprobe facility ( EAR-0732691 ). In addition we thank Peter Cawood and an anonymous reviewer for their timely and insightful comments and suggestions.
- Appalachian foreland basin
- Detrital monazite
- Detrital zircon
ASJC Scopus subject areas
- Geochemistry and Petrology
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science