can clastic rocks be used to reconstruct past provenance?
DESCRIPTION
This is a slide presentation for a literature review on studying provenance and clastic sedimentary rocksTRANSCRIPT
Can clastic rocks be used to reconstruct past
provenance?
Meg Stewart, AMNHNovember 7, 2014
Outline
• What is a provenance and what methods are used to look for provenance?
• Case studies in New York– Taconic orogeny sediments– Glacial history
Chile
Source Area
provenance or parent lithology
Chile
Source Area
weathering erosion abrasion sorting
Sedimentary Basin Chile
Source AreaSedimentary Basin
Sedimentary Basin
topography climate
Chile
• Stratigraphic sequences• Bulk chemistry• Cathodoluminescence• Isotope ages• Detrital zircons
Case study: Taconic Orogeny Sediments, New York
Modified from Ron Blakey at Northern Arizona University
Silurian Paleogeography~420 Ma
NEW YORKNEW JERSEY
PA CO
NN
EC
TIC
UT
Location of Shawangunk Conglomerate in New York
1 cm
Bernet, Kapoutsos & Bassett, 2007
Bernet, Kapoutsos & Bassett, 2007
McLennan, et al., 2001
Interpretation:The Silurian Shawangunk Conglomerate was deposited in an inland shallow sea. The topographic high was to the east of the sea. Clasts in the Shawangunk are not Taconic age but Grenvillian age. Provenance for the sediments was likely recycled, older sedimentary rocks exhumed in the orogeny.
Case study: Glacial history of New York
Long Island
Long Island
Pacholik, Gilbert, Hanson and Hemming 2001
Interpretation:Evidence of Wisconsinan glaciation on Long Island include two distinct moraine deposits and many glacial erratics (boulders). Provenance for the moraine is difficult to interpret because of obliteration of source rock and reworked sediments during the many glacial episodes. Provenance of the erratics show a range from the Long Inland Sound basement rock to Taconian age.
Conclusions
• Clastic rocks and sediments can help reconstruct provenance– Knowing the source rock tells the
direction the sediments came from• plate configurations• orogenesis• geomorphic changes