Plaza Gray

Submitted by Raven Mueller on Thu, 2014-07-10 09:25
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Physical Data
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Specimen: 2014-040
This is a minimally fossiliferous limestone. The limestone is not grain supported and has a predominantly micrite and/or neomorphic cement matrix. Allochems constitute about 20 percent of slide area. These characteristics classify the limestone as a wackestone. Allochem composition is about 80 percent peloid and 20 percent bioclast. These estimates classify this limestone as a sparse pelmicrite. Identifiable peloids are commensurate with faecal pellet origin. These likely constitute the majority of slide area, but compaction, dissolution, and neomorphism makes discernment not feasible in most of the limestone fabric. Peloids have a maximum size near .5 mm and a modal range around .15 mm. Bioclasts are a heterogeneous mix without a clear dominant form. Maximum dimensions of identified fossils are as follows: bryozoans 1 mm, bivalves 2.25 mm, foraminifera .5 mm, calcispheres .1 mm. Areas of consertal sparite may have formed as replacements of relic fossil. The form of the surrounding micritic envelope is often not sufficiently diagnostic for fossil identification, indicating the bioclast assemblage may be more diverse than presently indicated. Larger echinoderm fossils are visible in the hand sample but not captured on this slide. Other inclusions include collophane with a maximum dimension of .65 and authigenic quartz with a modal range around .1 mm; both are rare at far less than 1 percent of slide area. Extant voids are essentially absent. Iron hydroxide stained peloids are present and account for about 1 percent of slide area. This is not visible in the hand sample’s color, which is dominated by the gray color of the micrite. Compaction is difficult to assess but was potentially significant given the loss of peloid form.
MP 7/21/2015


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Specimen ID
2014-040 Image of specimen in dry conditions. Finish: download image Close-up image of specimen in dry conditions. Finish: download image Image of specimen in wet conditions. Finish: download image Close-up image of specimen in wet conditions. Finish: download image

Thin Sections

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Specimen ID Non-polarized Cross-polarized
2014-040 Specimen shown in non-polarized image Specimen shown in cross-polarized image


NOTE: Quarry locations are approximate.

Gray Quarry
[Lyon County] , Kansas
United States
Kansas US

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