provenance analysis. provenance: the lithological (and chemical, isotopic, age) characteristics of...

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Provenance Analysis

Provenance Analysis

1Provenance: the lithological (and chemical, isotopic, age) characteristics of the source region for a sedimentary rockComposition of sediments (mostly sandstones) can tell you about the location, tectonic setting, climate, etc. of the source area and the transport mechanism and pathway

2Mechanical weatheringNo changes to mineralogical composition of sediment produced from rock

Chemical weatheringMineralogical composition of sediment differs from parent rock3Chemical weathering dominates in warm, wet climates

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Mineral stability during weathering follows Bowens reaction series5

Compositional Maturity: degree to which sediment contains only resistant grains (quartz and stable heavy minerals like magnetite, apatite, rutile, zircon)6Textural Maturity: based on presence of clay, sorting, and roundingMore transport leads to greater textural maturity

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Rock particles can indicate the tectonic setting of the source QFL diagram plots relative percentages of quartz, feldspar, and lithicsIf chert or quartzite are abundant, treat them as lithics and plot monocrystalline quartz (Qm)8Qp = polycrystalline quartz (chert, quartzite)Lvm = volcanic and metavolcanic lithicsLsm = sedimentary and metased lithics

Lm = metamorphic lithicsLv = volcanic lithicsLs = sedimentary lithicsOther ternary plots (QpLvmLsm and LmLvLs) subdivide and plot just the lithic components for discrimination of tectonic settings9Sm/Nd isotopesNegative Nd values found in continental crust (Nd system has been separated from Sm enriched mantle for long time)Positive Nd values are commonly found in mantle derived melts

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Strontium isotopes (87Sr/86Sr)Rubidium (87Rb) strongly partitions into continental magmas and decays to 87Sr Continental crust is enriched in 87Sr/86SrPrimitive mantle and magma have low 87Sr/86SrRatio tracks continental influence on source rocks11

Detrital zircon U-PbSingle-crystal age dates give age of rocks in source region12