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Holocene paleoenvironments in southeastern Minnesota – chasing the prairie-forest ecotone
This paper uses a multi-proxy approach involving pollen, plant macrofossils, speleothem isotopes, and alluvial history of streams to reconstruct the history of prairie expansion and contraction alongExpand
Late Ordovician (Turinian–Chatfieldian) carbon isotope excursions and their stratigraphic and paleoceanographic significance
Five positive carbon isotope excursions are reported from Platteville–Decorah strata in the Upper Mississippi Valley. All occur in subtidal carbonate strata, and are recognized in the Mifflin, GrandExpand
Middle Cretaceous greenhouse hydrologic cycle of North America
We present a paleolatitudinal precipitation reconstruction for the greenhouse setting of mid-latitude North America based on the oxygen isotopic composition of sphaerosiderites found in middleExpand
Meteoric sphaerosiderite lines and their use for paleohydrology and paleoclimatology
Sphaerosiderite, a morphologically distinct millimeter-scale spherulitic siderite (FeCO 3 ), forms predominantly in wetland soils and sediments, and is common in the geologic record. AncientExpand
Speleothem Evidence for Changes in Indian Summer Monsoon Precipitation over the Last ∼2300 Years
Abstract Speleothems from a well-ventilated dolomitic cave in the Pokhara Valley, central Nepal, preserve a mineralogic record of Indian summer monsoon variability over the past 2300 yr. AnnuallyExpand
Surface chemistry allows for abiotic precipitation of dolomite at low temperature
Results indicate that natural surfaces, including organic matter and microbial biomass, possessing a high density of carboxyl groups may be a mechanism by which ordered dolomite nuclei form, and suggest that sharp biogeochemical interfaces that promote microbial death, as well as those with high salinity may, in part, control car boxyl-group density on organic carbon surfaces. Expand
Microbial precipitation of dolomite in methanogenic groundwater
We report low-temperature microbial precipitation of dolomite in dilute natural waters from both field and laboratory experiments. In a freshwater aquifer, microorganisms colonize basalt and nucleateExpand
Detrital zircon provenance of Cambrian–Ordovician and Carboniferous strata of the Oaxaca terrane, southern Mexico
Abstract U–Pb geochronologic analyses have been conducted on 135 detrital zircon grains from Paleozoic strata of the Oaxaca terrane of southern Mexico. The grains are mainly mid-Proterozoic in ageExpand
The mid-Cretaceous water bearer: isotope mass balance quantification of the Albian hydrologic cycle
A latitudinal gradient in meteoric N 18 O compositions compiled from paleosol sphaerosiderites throughout the Cretaceous Western Interior Basin (KWIB) (34^75‡N paleolatitude) exhibits a steeper, moreExpand
Precipitation of low-temperature dolomite from an anaerobic microbial consortium: the role of methanogenic Archaea.
Here we report precipitation of dolomite at low temperature (30 degrees C) mediated by a mixed anaerobic microbial consortium composed of dissimilatory iron-reducing bacteria (DIRB), fermenters, andExpand