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Drainage reorganization during breakup of Pangea revealed by in-situ Pb isotopic analysis of detrital K-feldspar
Date Issued
2007-11
Date Available
2011-08-02T16:16:14Z
Abstract
The Pb isotopic composition of detrital K-feldspar grains can be rapidly measured using laser ablation MC-ICPMS. The feldspar Pb signal can survive weathering, transport and diagenesis, and careful targeting avoids problems with inclusions and alteration. As common Pb isotopic compositions show broad (100s km scale) variation across the continents, the method provides a powerful provenance tracer for feldspathic sandstones. Here we combine a new Pb domain map for the circum-North Atlantic with detrital feldspar Pb isotopic data for Triassic and Jurassic sandstones from basins on the Irish Atlantic margin. The Pb compositions reveal otherwise cryptic feldspar populations that constrain the evolving drainage pattern. Triassic sandstones were sourced from distant Archean and Paleoproterozoic rocks, probably in Greenland, Labrador and Rockall Bank to the NW, implying long (>500 km) transport across a nascent rift system. Later Jurassic sandstones had a composite Paleo- and Mesoproterozoic source in more proximal sources to the north (<150 km away). Little or no feldspar was recycled from Triassic into Jurassic sandstones, and the change in provenance is consistent with distributed, low relief Triassic extension in a wide rift, followed by narrower Jurassic rifting with more localised fault-controlled sediment sources and sinks.
Sponsorship
Not applicable
Other Sponsorship
Petroleum Infrastructure Programme (PIP)
Enterprise Ireland
Type of Material
Journal Article
Publisher
The Geological Society of America
Journal
Geology
Volume
35
Issue
11
Start Page
971
End Page
974
Copyright (Published Version)
2007 The Geological Society of America
Subject – LCSH
Lead--Isotopes
Pangaea (Supercontinent)
Feldspar
Geology, Stratigraphic--Mesozoic
Web versions
Language
English
Status of Item
Peer reviewed
This item is made available under a Creative Commons License
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