Provenance Analysis Provenance the lithological and chemical isotopic
- Slides: 12
Provenance Analysis
Provenance: the lithological (and chemical, isotopic, age) characteristics of the source region for a sedimentary rock Composition of sediments (mostly sandstones) can tell you about the location, tectonic setting, climate, etc. of the source area and the transport mechanism and pathway
Mechanical weathering No changes to mineralogical composition of sediment produced from rock Chemical weathering Mineralogical composition of sediment differs from parent rock
Chemical weathering dominates in warm, wet climates
Mineral stability during weathering follows Bowen’s reaction series
Compositional Maturity: degree to which sediment contains only resistant grains (quartz and stable heavy minerals like magnetite, apatite, rutile, zircon)
Textural Maturity: based on presence of clay, sorting, and rounding More transport leads to greater textural maturity
Rock particles can indicate the tectonic setting of the source QFL diagram plots relative percentages of quartz, feldspar, and lithics If chert or quartzite are abundant, treat them as lithics and plot monocrystalline quartz (Qm)
Other ternary plots (Qp. Lvm. Lsm and Lm. Lv. Ls) subdivide and plot just the lithic components for discrimination of tectonic settings Qp = polycrystalline quartz (chert, quartzite) Lm = metamorphic lithics Lvm = volcanic and metavolcanic lithics Lv = volcanic lithics Lsm = sedimentary and metased lithics Ls = sedimentary lithics
Sm/Nd isotopes Negative εNd values found in continental crust (Nd system has been separated from Sm “enriched” mantle for long time) Positive εNd values are commonly found in mantle derived melts
Strontium isotopes (87 Sr/86 Sr) Rubidium (87 Rb) strongly partitions into continental magmas and decays to 87 Sr Continental crust is enriched in 87 Sr/86 Sr Primitive mantle and magma have low 87 Sr/86 Sr Ratio tracks continental influence on source rocks
Detrital zircon U-Pb Single-crystal age dates give age of rocks in source region
- Clvalence electrons
- Isotopic notation
- Isotopic notation example
- What does the number represent in the isotope platinum-194
- Isotope name
- Facts about electrons
- Isotopic antenna
- Antenna gain formula examples
- Atomic mass of boron-10
- Magnesium atomic number
- Isotope notation definition
- What is provenance
- Provenance semirings