Need for Redefinition of North American Pleistocene Stages: ABSTRACT

Boellstorff, John

doi:10.1306/c1ea52a1-16c9-11d7-8645000102c1865d

Cited by 6 publications

(14 citation statements)

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“…The "B type" till underlies the "A type" tills, but has been identified at only a few sites. Its composition is characterized by approximately 60 to 80% sedimentary pebbles (Boellstorff, 1978b(Boellstorff, , 1978c.…”

Section: Introductionmentioning

confidence: 99%

Pre-Illinoian Glacial Stratigraphy in North-Central Missouri

Rovey

Kean

1996

Quat. res.

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Five pre-Illinoian tills are recognized and named informally in northern Missouri, near the southernmost margin of the pre-Illinoian Laurentide ice sheet. The three youngest tills (McCredie formation) have high (50–60%) expandable clay mineral contents and normal remanent magnetic polarity. The next oldest till (Moberly formation) has low (30–40%) expandable clay content and reversed polarity. The oldest till (Atlanta formation) has very low or no expandable clay minerals. Its remanent magnetic polarity is unknown.The sequence of four pre-Illinoian tills above the Atlanta formation probably correlates with the similar sequence of four pre-Illinoian “A type” tills in western Iowa and eastern Nebraska. The upper four tills in Missouri are also correlated, in order of increasing age, with the three members of the Wolf Creek Formation and the older Alburnett Formation in eastern Iowa. The oldest till in Missouri possibly correlates with the “C type” till in western Iowa.Pre-Illinoian Laurentide ice reached the same approximate southern margin at least five times. Those advances deposited tills which maintain characteristic compositions over distances of at least 350 km along flow lines.

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Section: Introductionmentioning

confidence: 99%

Pre-Illinoian Glacial Stratigraphy in North-Central Missouri

Rovey

Kean

1996

Quat. res.

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“…However, the values attributed to glacial melt water were more enriched (δ 18 O = −15 to −10 SMOW) than those observed in the western portion of the study area. Glacial advance during the last glacial maximum stopped at the Missouri River, the northern boundary of the study area (Boellstorff 1978), thus the potential for glacial recharge affecting water in the study area was considered. However, most of the 14 C ages from the group of older water indicate recharge occurred in an interglacial period for the area.…”

Section: Discussionmentioning

confidence: 99%

A Black Hills‐Madison Aquifer Origin for Dakota Aquifer Groundwater in Northeastern Nebraska

2010

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Previous studies of the Dakota Aquifer in South Dakota attributed elevated groundwater sulfate concentrations to Madison Aquifer recharge in the Black Hills with subsequent chemical evolution prior to upward migration into the Dakota Aquifer. This study examines the plausibility of a Madison Aquifer origin for groundwater in northeastern Nebraska. Dakota Aquifer water samples were collected for major ion chemistry and isotopic analysis (18O, 2H, 3H, 14C, 13C, 34S, 18O‐SO4, 87Sr, 37Cl). Results show that groundwater beneath the eastern, unconfined portion of the study area is distinctly different from groundwater sampled beneath the western, confined portion. In the east, groundwater is calcium‐bicarbonate type, with δ18O values (−9.6 to −12.4) similar to local, modern precipitation (−7.4 to −10), and tritium values reflecting modern recharge. In the west, groundwater is calcium‐sulfate type, having depleted δ18O values (−16 to −18) relative to local, modern precipitation, and 14C ages 32,000 to more than 47,000 years before present. Sulfate, δ18O, δ2H, δ34S, and δ18O‐SO4 concentrations are similar to those found in Madison Aquifer groundwater in South Dakota. Thus, it is proposed that Madison Aquifer source water is also present within the Dakota Aquifer beneath northeastern Nebraska. A simple Darcy equation estimate of groundwater velocities and travel times using reported physical parameters from the Madison and Dakota Aquifers suggests such a migration is plausible. However, discrepancies between 14C and Darcy age estimates indicate that 14C ages may not accurately reflect aquifer residence time, due to mixtures of varying aged water.

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“…The Pearlette volcanic ash was likewise proven to actually be several ash beds of greatly different ages (Naeser et al 1973;Boelstorff 1976). The terms Nebraskan and Kansan came to be used by some geologists to mean the first and second continental glaciations in a conceptual sense quite different from the classical stratigraphy (Boellstorff 1978b).…”

Section: Revision Of Glacial Stratigraphymentioning

confidence: 99%

The glaciation of northeastern Kansas

Aber

1991

Boreas

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The traditional pre‐Illinoian glacial stratigraphy in the central United States has been abandoned, which leaves a void in the Pleistocene stratigraphy of Kansas. The Independence Formation is proposed as a tithostratigraphic unit in northeastern Kansas. The Independence Formation consists of all diamictons and stratified sediments interbedded with diamictons. The Independence Formation vanes greatly in thickness and texture, but it always contains erratics derived from the Canadian Shield. At least two glacial advances took place in northeastern Kansas, first by the Minnesota lobe coming from the northeast, and later by the Dakota lobe from the northwest. During the first advance, glacial Lake Atchison was dammed in a now‐buried valley. Overflow from this lake cut spillways that form parts of the Blue, Kansas, and Missouri valleys. During the later ice advance, the Kansas valley was blocked, and temporary lakes formed, from which catastrophic flooding took place. The age of the Independence Formation is interpreted as 0.7 to 0.6 million years BP. It is considered equivalent in age and stratigraphic position to type A2 and A3 tills of Nebraska and western Iowa and to the McCredie Formation of northern Missouri. This age range corresponds to oxygen‐isotope stages W16.

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Need for Redefinition of North American Pleistocene Stages: ABSTRACT

Cited by 6 publications

References 0 publications

Pre-Illinoian Glacial Stratigraphy in North-Central Missouri

Pre-Illinoian Glacial Stratigraphy in North-Central Missouri

A Black Hills‐Madison Aquifer Origin for Dakota Aquifer Groundwater in Northeastern Nebraska

The glaciation of northeastern Kansas

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