Drainage reorganization during breakup of Pangea revealed by in-situ Pb isotopic analysis of detrital K-feldspar

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Title: Drainage reorganization during breakup of Pangea revealed by in-situ Pb isotopic analysis of detrital K-feldspar
Authors: Tyrrell, Shane
Haughton, Peter D. W.
Daly, J. Stephen
Permanent link: http://hdl.handle.net/10197/3058
Date: Nov-2007
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.
Funding Details: Not applicable
Type of material: Journal Article
Publisher: The Geological Society of America
Copyright (published version): 2007 The Geological Society of America
Keywords: Pb isotopesPalaeodrainageProvenancePangeaCorrib gasfieldAtlantic marginK-feldsparTriassic
Subject LCSH: Lead--Isotopes
Pangaea (Supercontinent)
Feldspar
Geology, Stratigraphic--Mesozoic
DOI: 10.1130/G4123A.1.
Language: en
Status of Item: Peer reviewed
Appears in Collections:Earth Sciences Research Collection

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