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Full-Text Articles in Geology
Mercury Increases In Lake Tanganyika Since ~1850, Troy A. Bole
Mercury Increases In Lake Tanganyika Since ~1850, Troy A. Bole
Williams Honors College, Honors Research Projects
A series of three sediment cores were collected in Lake Tanganyika, Africa, and were analyzed for mercury concentrations. For all three cores, a decrease in mercury (Hg) levels was observed from the 1600’s (appx. 20 ng/g) until concentrations reached a minimum during the mid-1800’s (appx. 10 ng/g). The mid-1800’s marked a change from decreasing mercury levels to an increase over the following century. The core tops (circa 2006) have concentrations greater than 70 ng/g. The onset of the rise in mercury concentrations coincides with the beginning of the Industrial Revolution in the mid to late 18th century. Relationships between …
Preservation Of Sea Anemone Burrows In Silurian (~432 Million Years Old) Carbonate Rocks Of Southeastern Indiana, Usa, Marissa Tomin
Preservation Of Sea Anemone Burrows In Silurian (~432 Million Years Old) Carbonate Rocks Of Southeastern Indiana, Usa, Marissa Tomin
Williams Honors College, Honors Research Projects
Preservation of trace fossils (ichnofossils) in siliciclastic environments is often quite different from preservation in carbonate environments, representing an important source of variation that must be well understood in order to enhance interpretations of paleoenvironments and paleoecology. This study focuses on Conostichus, a relatively common burrow constructed by solitary sea anemones. These trace fossils are generally well-preserved (i.e., they display detailed external features) in siliciclastic rocks but are typically little more than conical masses in carbonate rocks. However, certain specimens recovered from the middle Silurian Massie Formation at the Napoleon quarry of southeastern Indiana are composed entirely out of …
Pressure Dependence Of Polycrystalline Magnesite And Dolomite, Cole Blasko
Pressure Dependence Of Polycrystalline Magnesite And Dolomite, Cole Blasko
Williams Honors College, Honors Research Projects
Intermediate depth (170-400 km) deep focus earthquakes are observed in subducting slabs, but unlike shallow (50-170 km) and deep (400-660 km) deep focus earthquakes, the mechanism(s) responsible for them are not clear. Two common alteration products observed in peridotites, magnesite and dolomite, are stable along the pressure-temperature path of a subducting slab. Low pressure experiments indicate that these minerals are weaker than olivine, but there are no data about the pressure dependence of the strength of magnesite or dolomite. Magnesite and dolomite cylinders (1mm by 1mm) were deformed in stacked series to 25-30% strain using the deformation-DIA (DDIA) at Argonne …