111620d

 

 

Eroded edge of a microbial reef buried by wackestone (lime mud containing floating larger fragments). Thin section photomicrograph, Mississippian, North Alabama, field of view one millimeter wide. B=boundstone/reef, W=wackestone, two central arrows point to eroded edge of boundstone, left arrow points to piece of boundstone floating in wackestone.

060420b

behind the dresser

termites carve their tunnels

metropolis

042220c

A new mound-building fossil (micro-alga?) from Alabama, Journal of Paleontology:

DOI: https://doi.org/10.1017/jpa.2019.103

These critters had relatives across the southeastern U.S. and western Europe, which were pretty close together 300+ million years ago, when they were living.

112519

Ostracode filled with pelletal cement followed by calcite cement, later partly silicified. Calcite red, silica white, dolomite dark gray. Lower part of a small mound, Bangor Limestone, Mississippian, Haletown Tennessee. Silica is bright white, calcite is red, dolomite is dull dark gray. Thin section photomicrograph, stained with alizarin red S, image 2.5 mm wide.

A Mississippian carbonate mound thin section

What is it? Suggestions include a tubular calcimicrobe or encrusting foraminifer.

My latest geological publication

Kopaska-Merkel, David C., and Haywick, Douglas W., 2014, Small carbonate buildups in the Bangor Limestone (Chesterian) in and near Alabama, in, Puckett, T. Markham, and Rindsberg, Andrew K., eds., Stratigraphy and depositional systems in the Mississippian strata of the Appalachian Plateau, northwest Alabama, A guidebook for the 51st annual field trip, Alabama Geological Society, Tuscaloosa, p. 111-138.

Abstract

Carbonate mounds in the Mississippian of Alabama are small, unobtrusive, and sparsely distributed. Of eight known mounds, six are in the Bangor Limestone (Chesterian), one is in the Pennington Formation (late Chesterian), and one is in the Tuscumbia Limestone (Meramecian), in the subsurface. Nine other small mounds are known from the Bangor in southeastern Tennessee. A small Bangor mound in Blount County, first described as a rugose coral colony by Andronaco (1986), is here reinterpreted as a composite of coral colonies and muddy domains held up by a consortium of microbes, sponges, and fenestrate bryozoans. This is the first such mound reported from the Bangor.

You like these rock pictures don't you?

Void in carbonate mound. Bottom part is filled with micropelletal cement and a few chunks that fell off the roof of the void. Upper part filled with typical void filling calcite cement. All of the calcite is stained pink with alizarin red S.

Bioherm/mound - like a reef

Note chambered microfossils radiating from point of origin.

Some pictures of rocks