Composition, crystalline structure and microstructural anisotropy of limestone is investigated by means of instrumental neutron activation analysis (INAA), X-ray diffraction (XRD), neutron diffraction (ND) and measurement of anisotropy of magnetic susceptibility (AMS) and anisotropy of resonant ultrasound spectroscopy (ARUS).
The samples were collected near Choteč, Bohemia (Na Škrábku quarry, SE corner; 49°59'19.57" N, 14°16'44.16" E), from a single overturned/recumbent fold. Elementary composition of the investigated limestone (INAA) is dominated by Ca (34.72 mass %), Mg (4733 ppm), Fe (2253 ppm), K (1967 ppm) and Al (1185 ppm). In addition, traces of another 33 elements are present having concentration higher then 1 ppm. Total organic carbon (TOC) concentration is only ~0.15 mass %. Calcite (~ 98.5+-1 mass %) and quartz (~ 1.5+-1 mass %) were identified by phase analysis of XRD powder patterns as the prevailing mineral phases. Based on ND powder data, crystalline structure of calcite was refined within the space group R-3c giving the lattice parameters a = 0.4915(4) nm and c = 1.6800(14) nm.
Crystallographic preferential orientation (CPO) of the crystalline calcite cement filling the initial sediment pores is weak (XRD and ND data). Obtained ARUS patterns exhibit sharp resonances approving the complete pore filling. The calculated sharpness (f) of the orientation distribution functions (ODF) calculated for individual samples was f < 3. The observed mean polar angle (Beta) between the c-poles and the original sedimentation direction (SD) varies with the point of sample collection within the broad range: Beta = 0^o - 60^o. Orientation of (110) poles around the <0001> direction is practically isotropic.
Small positive values of the mean magnetic susceptibility (χ) were obtained by KLY-2 bridge measurement): χ = 3 - 8 x 10^-9 m³ kg^-1. It is apparent that the intrinsic diamagnetic contribution of calcite is balanced by an extrinsic para-/ferro-magnetic contribution. Noisy AMS results caused only the direction of the pole to the magnetic foliation (MF) could be identified. The observed mean MF deflection from SD varies in accord with the textural Beta-value.

This research has been supported by grants MSM6840770040, AV0Z30130516 and GACR205/08/0767.

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