Radish concretions grown in mud during compaction

Radish concretions exhibit a typical columnar to pear-shaped, stipe downward geometry. In Middle Jurassic mudrock in south-west Germany, radish started form around an iron-sulphide lined tube by pervasive cementation constituting ellipsoidal parent domain uncompacted sediment at burial depths of ≤5 8 m as recorded 75 80% minus-cement porosity. Thereafter, the grew vertically compacting evidenced laminae within being increasingly inclined towards tips, and concomitantly decreasing During early diagenesis, prior septarian crack formation, bicarbonate generating microbial cement originated sulphate reduction zone chiefly from anaerobic oxidation methane lesser degree organoclastic material. Later, 50 70 depth, cracks formed evaluated sedimentation–compaction analysis based on porosity data compressibility similarly composed sediments. The outward-narrowing indicate that they when were still plastic state but already cemented sufficiently be resistant against compaction. this stage, up one-quarter pore volume was open suggested shrinkage experiments. This volume, cracks, filled with termed late diagenetic. study area, decompacted net-sedimentation rate low, about 2 3 cm kyr−1, for ca 2.5 Myr, allowing reside long time grow. transition thick, rapidly deposited long-term, slowly accumulating sediment.