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NARROW
GeoRef Subject
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all geography including DSDP/ODP Sites and Legs
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United States
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Georgia
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Dade County Georgia (1)
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Illinois
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Calhoun County Illinois (1)
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Will County Illinois (1)
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Tennessee
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Hamilton County Tennessee (4)
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Sequatchie County Tennessee (1)
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elements, isotopes
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carbon
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C-13/C-12 (2)
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isotope ratios (2)
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isotopes
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stable isotopes
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C-13/C-12 (2)
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O-18/O-16 (2)
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oxygen
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O-18/O-16 (2)
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fossils
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Invertebrata
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Brachiopoda
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Articulata
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Pentamerida (1)
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geochronology methods
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Th/U (1)
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geologic age
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Cenozoic
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Quaternary
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Holocene (1)
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Paleozoic
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Silurian
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Lower Silurian
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Llandovery
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Rhuddanian (1)
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minerals
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carbonates
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siderite (1)
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Primary terms
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absolute age (1)
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carbon
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C-13/C-12 (2)
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Cenozoic
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Quaternary
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Holocene (1)
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geochemistry (1)
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hydrology (1)
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Invertebrata
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Brachiopoda
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Articulata
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Pentamerida (1)
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isotopes
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stable isotopes
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C-13/C-12 (2)
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O-18/O-16 (2)
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oxygen
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O-18/O-16 (2)
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paleoclimatology (1)
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Paleozoic
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Silurian
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Lower Silurian
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Llandovery
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Rhuddanian (1)
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pollution (2)
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sedimentary rocks
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carbonate rocks (1)
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soils
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Alluvial soils (1)
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Clay soils (1)
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United States
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Georgia
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Dade County Georgia (1)
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Illinois
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Calhoun County Illinois (1)
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Will County Illinois (1)
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Tennessee
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Hamilton County Tennessee (4)
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Sequatchie County Tennessee (1)
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rock formations
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Red Mountain Formation (1)
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sedimentary rocks
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sedimentary rocks
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carbonate rocks (1)
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soils
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paleosols (1)
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soils
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Alluvial soils (1)
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Clay soils (1)
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Hamilton County Tennessee
Platymerella —a cool-water virgianid brachiopod fauna in southern Laurentia during the earliest Silurian
Speleothems are valuable archives of climate change because of their extraordinary time resolution, which is unattainable in other terrestrial climate proxies. Analyses of 4796 ultraviolet fluorescent (UVf) layers observed in polished thin sections of a 15-cm-long speleothem collected from Raccoon Mountain Cave near Chattanooga, Tennessee, USA, as well as 200 δ 13 C and δ 18 O measurements and 11 high-precision U/Th dates permit refined interpretations of middle and late Holocene paleoclimate records in the southeastern United States. Speleothem UVf layers average 0.015 mm, identical to the average growth rate determined for the middle and late Holocene portions of the speleothem (ca. 7600–400 yr B.P.) based on the U/Th ages and interval thicknesses. UVf layer counts between paired U/Th ages are also consistent with determined ages and further support their interpretation as annual layers. The middle Holocene is typified by 100–400 yr intervals of higher rainfall characterized by thin UVf layers (0.003–0.010 mm) and more-negative δ 13 C values (−3‰ to −6‰ Peedee belemnite [PDB]), punctuated by shorter periods (5–20 yr, rarely 50–100 yr) of lower rainfall with thicker UVf layers (0.030–0.080 mm) and less-negative δ 13 C values (−1‰ to −3‰ PDB); “extreme drought” events are characterized by both the thickest UVf layers (0.150–0.170 mm) and the least-negative δ 13 C values (+0.05‰ to −1‰ PDB). The late Holocene, in comparison, is characterized by overall wetter conditions and more regular (sinusoidal curve) behavior, suggesting 50–100 yr cycles of higher and lower rainfall, with UVf layers ranging from 0.005 to 0.030 mm/yr. Statistical analyses of UVf layer thicknesses using order-two momentum threshold vector autoregressive models (MTVAR2) quantify the relationship between δ 13 C and δ 18 O, dependent upon the momentum in the climate. This study demonstrates that thickness of annual layers in speleothems can be used to resolve detailed paleorainfall records, provided there is preservation of organic matter sufficient to excite UVf response; however, relationships among changes in rainfall amounts, stable isotope values of speleothem calcite, and thicknesses of UVf annual layers (≈growth rates) are not straightforward.
Coal mining impacts and remediation in the Chattanooga region: Field trip to North Chickamauga Creek upper watershed
Abstract Upper North Chickamauga Creek in Hamilton and Sequatchie Counties, Tennessee, is severely impacted by acid mine drainage (AMD) emanating from more than 15 abandoned coal mines in headwater tributaries. AMD is formed when pyrite and other sulfide minerals are exposed to air and water during coal mining. It is characterized by low pH (<2.8) and elevated concentrations of acidity, iron, aluminum, sulfate, and other pollutants. These attributes tend to be toxic to most aquatic life and result in reduced aesthetics and potential uses of the water. The North Chickamauga Creek Watershed Restoration Project is a multi-organizational effort to restore the upper 18 miles of the North Chickamauga Creek watershed to a level that will support a warm-water fishery. Several passive treatment systems (PTS) have been installed at abandoned mining sites in the North Chickamauga Creek watershed where AMD is generated and is flowing into surface waters. PTS is the engineered use of natural and enhanced geological, biological, chemical, and physical processes to prevent pollutant generation or to remove pollutants from aqueous discharges. PTS include technologies such as constructed wetlands, anoxic limestone drains, mine seals and flooding, successive alkalinity-producing systems, limestone trenches, and other components. During this field trip to the upper reaches of the North Chickamauga Creek watershed, we will visit several of the operational systems and observe untreated AMD. Participants will gain an understanding of how AMD is generated, its impacts and characteristics, and how it can be prevented or treated. This field trip requires extensive hiking over moderate slopes and sometimes vegetated terrain.