A shift from lithostratigraphic to allostratigraphic classification of Quaternary glacial deposits: COMMENT

Johnson, Mark D.; Jennings, Carrie E.; Hobbs, H.C.

doi:10.1130/gsatg52c

Cited by 3 publications

(1 citation statement)

References 1 publication

(5 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The dashed, green line separates thick, extensive, clay‐rich Des Moines lobe Quaternary sediment to the west, from sandier, generally thinner, and patchier Quaternary sediment to the east. (After Runkel et al 2006; green line is after Johnson et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Documentation and Prediction of Increasing Groundwater Chloride in the Twin Cities, Minnesota

et al. 2022

View full text Add to dashboard Cite

We provide a comprehensive overview of historic chloride concentrations in the groundwater of the Twin Cities metropolitan area (TCMA) in Minnesota, in order to define the extent of chloride contamination, due primarily to the seasonal application of deicing salt to roadways. Data collected from 1278 wells between 1965 and 2020 are representative of the major aquifers underlying the TCMA and establish a regional natural background chloride concentration of less than 10 mg/L. However, 55% of all measurements (1616 of 2943) are above 10 mg/L, with the highest concentrations found within the uppermost Quaternary aquifers. Chloride concentrations in underlying bedrock aquifers are negatively correlated with the thickness and clay composition of overlying materials. Most chloride measurements (92%) remain below chronic exposure limits set by state and federal authorities. Historical trends indicate that, if the current imbalance between chloride inputs and outflows persists, chloride concentrations in TCMA aquifers will surpass regulatory thresholds by midcentury as surface waters and Quaternary aquifer waters migrate into underlying bedrock aquifers. Most wells in this study are monitored annually, making it impossible to detect important sub-annual fluctuations of chloride concentration that can exceed 40%.

show abstract

Section: Introductionmentioning

confidence: 99%

Documentation and Prediction of Increasing Groundwater Chloride in the Twin Cities, Minnesota

et al. 2022

View full text Add to dashboard Cite

show abstract

Surficial geological tools in fluvial geomorphology

Jacobson

O'Connor

Oguchi

2016

Tools in Fluvial Geomorphology

View full text Add to dashboard Cite

Geomorphology and Quaternary stratigraphy: The roles of morpho-, litho-, and allostratigraphy

Hughes

2010

Geomorphology

View full text Add to dashboard Cite

a b s t r a c tThe subdivision and ordering of Quaternary sediments and landforms is very often based on geomorphology. Quaternary landforms such as moraines, river terraces, palaeoshorelines, and indeed any other landform, can be arranged and ordered in time based on their relative position in the landscape. Morphostratigraphy is the subdivision of sedimentary units primarily on the basis of surface form. Whilst surface form is often used as a criterion for separating sedimentary units, morphostratigraphy also usually incorporates lithological criteria to aid stratigraphical subdivision, and morpho-and lithostratigraphy are often interlinked in Quaternary science. However, another approach-allostratigraphy-has increasingly been applied to subdivide and order Quaternary sediment landforms. Allostratigraphy uses discontinuities to subdivide sedimentary successions. Allostratigraphy enables lateral variations in lithology to be included within the same stratigraphical unit. Furthermore, it enables lithologically similar sediments stacked on top of each other to be divided into separate units based on discontinuities. This paper examines the applications of morpho-, litho-and allostratigraphy to subdivide sediment-landform assemblages and critically reviews their role in Quaternary stratigraphy.

show abstract

A shift from lithostratigraphic to allostratigraphic classification of Quaternary glacial deposits: COMMENT

Cited by 3 publications

References 1 publication

Documentation and Prediction of Increasing Groundwater Chloride in the Twin Cities, Minnesota

Documentation and Prediction of Increasing Groundwater Chloride in the Twin Cities, Minnesota

Surficial geological tools in fluvial geomorphology

Geomorphology and Quaternary stratigraphy: The roles of morpho-, litho-, and allostratigraphy

Contact Info

Product

Resources

About