051419b

Mixed-particle grainstone cemented by well-developed pore-rimming calcite cement (probably altered from original marine aragonite cement). Deposited in a high-energy shallow marine environment. Jurassic Smackover Formation, Alabama. Stained with alizarin red S. Thin section photomicrograph. Field of view 2.5 mm wide.

041819

Grainstone composed almost exclusively of Parafavreina, a fecal pellet made by burrowing shrimp. This deposit is almost identical to modern accumulations of fecal pellets made by related burrowing-shrimp.This thin section was stained with Alizarin red S, staining calcite pink. White particles are quartz silt grains.. Light pink areas are calcite cement crystals filling original open spaces among the pellets. Jurassic Smackover Formation, Alabama, image 2.5 mm wide.

The photos of Parafavreina that I have been posting were taken in the process of preparing this scientific article:

Rindsberg, A. K., and Kopaska-Merkel, D. C., 2013 , Parafavreina ziczac isp. nov., a crustacean microcoprolite from the Upper Jurassic (Oxfordian) Smackover Formation of Alabama, U.S.A., Alabama Museum of Natural History Bulletin 31, v. 2. p. 74-93.

I have PDF copies of the article if anyone is interested.

041719d

Dolomite (gray) partially replacing calcite (pink) in a mixed-particle grainstone cemented with marine cement crystals (light pink). Particle in the center is a shrimp fecal pellet. 13,000 feet below the surface, Jurassic Smackover Formation, thin section photomicrograph, field of view 2.5 mm wide

032419

Cross-laminated oolitic dolomitized grainstone, Jurassic, Smackover Formation, porous oil reservoir, North Choctaw Ridge Field, Alabama, five-centavo piece for scale.

031919

Partially dolomitized ooid grainstone. Some ooid laminae, and some cement generations, are still calcite. Bright white objects are quartz sand particles. Jurassic Smackover Formation, Alabama, thin-section photomicrograph, stained with Alizarin Red S.

031819

Intraclast, thinly coated and consisting of three orids, therefore technically a compound ooid, in mixed-particle grainstone, Jurassic Smackover Formation, subsurface of south Alabama, thin-section photomicrograph.

031319

Skeletal grainstone, Bangor Limestone, Mississippian, Alabama. Thin-section photomicrograph.