Extensive calcite fault cement has resulted from leakage of Santa Barbara basin fluids and hydrocarbons into the Refugio-Carneros fault, a north-bounding structure to the basin. Calcite cements are only found at the end segments of the 24-km (15-mi)-long fault zone, which has less than 150 m (490 ft) of maximum normal offset. The calcite is contemporaneous with fault movement, as evidenced by p...

In terms of its sub-regional differentiation, the hippocampal CA1 region receives cortical information directly via the perforant (temporoammonic) path (pp-CA1 synapse) and indirectly via the tri-synaptic pathway where the last relay station is the Schaffer collateral-CA1 synapse (Sc-CA1 synapse). Research to date on pp-CA1 synapses has been conducted predominantly in vitro and never in awake a...

The study of the carbonate cements in the Permian-Triassic Dalan-Kangan formations resulted in the identification of five stages of calcite and dolomite cementation, which completely or partially occluded pores. Cement types appear to be early isopachous calcite (i; C1-non-luminescence), equant (ii; C2-dull CL), fairly coarse secondary dolomite rhombs (iii; C3-zoning red CL), coarse sparry calc...

A characterization study was performed on the spent oil shale (oil shale ash) obtained from the combustion of Jordanian oil shale. This characterization utilized different analytical techniques. These include scanning electron microscope with energy dispersive spectrum analysis, X-ray fluorescence, X-ray diffraction and Qemscan. During the combustion process, minimal fragmentation was encounter...

Using three different microscopy techniques (epifluorescence, electronic and atomic force microscopy), we showed that high-Mg calcite grains in calcifying microbial mats from the hypersaline lake "La Salada de Chiprana", Spain, contain viruses with a diameter of 50-80 nm. Energy-dispersive X-ray spectrometer analysis revealed that they contain nitrogen and phosphorus in a molar ratio of ~9, whi...

The mechanisms of formation of biogenic magnesium-rich calcite remain an enigma. Here we present ultrastructural and compositional details of ossicles from the seastar Pisaster giganteus (Echinodermata, Asteroidea). Powder X-ray diffraction, infrared spectroscopy and elemental analyses confirm that the ossicles are composed of magnesium-rich calcite, whilst also containing about 0.01 % (w/w) of...

Many organisms form minerals from precursor phases that crystallize under strict biological control. The dynamic intracellular processes of formation, transport, and deposition of these precursor phases are challenging to identify. An unusual situation is recently revealed for the calcifying alga Emiliania huxleyi, as the cells contain a compartment filled with a concentrated Ca and P phase but...

The diagenetic changes of the Lower-Middle Eocene limestones in the area to the west of AssiutMinia Stretch include the following processes: compaction, cementation, neomorphism, silicification, glauconitization and ferrugination. The compaction is represented by mechanical and chemical types. Cementation is either shallow submarine (represented by micrite, fibrous calcite and isopachous calcit...

Powdery calcium carbonates, predominantly calcite and aragonite, with planar defects and cation-anion mixed surfaces as deposited on low-carbon steel by magnetic water treatment (MWT) were characterized by X-ray diffraction, electron microscopy, and vibration spectroscopy. Calcite were found to form faceted nanoparticles having 3x (01̄14) commensurate superstructure and with well-developed {112̄0...

Petrographic study of the Frewens sandstone, Upper Cretaceous Frontier Formation, documents reservoir-scale diagenetic heterogeneity. Iron-bearing calcite cement occurs as large concretions that generally follow bedding and are most common near the top of the sandstone. Median thickness of the concretions is 0.6 m, length 4.5 m, and width 5.7 m; median volume is 5.2 m. Concretions comprise 12% ...