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Electron microprobe analysis was performed on three of the samples collected. The analysis verified the existence of four main mineral phases and the composition of detrital grains included within the travertines. The main mineral phases consisted of primary aragonite, Mg-calcite, low-temperature primary dolomite, and sepiolite clay. All travertine samples were also found to contain abundant detrital grains of greywacke and serpentinite. X-ray diffraction confirmed the identity of the three carbonate minerals. SEM analysis confirmed the presence of sepiolite. The pictures included below are back-scattered electron images taken with the electron microprobe showing arrangement of the mineral phases and their textures as well as two SEM photographs of fibrous sepiolite.

Sample 7-1

Figure (photo left) shows bladed aragonite crystals growing into pore space. Nodules consisting of Mg-calcite cores and dolomite rims (5-10mm) occur between aragonite crystals (Inset).

The aragonite crystal faces are unaltered and dolomite occurs as a rim around Mg-calcite, not as rhombs within, suggesting that the dolomite is of primary origin and not a product of secondary diagenetic alteration of aragonite or Mg-calcite.

Sample 7-1

Image (photo right) showing alternating bands of aragonite, Mg-calcite, dolomite, and sepiolite, representing seasonal variations in the water flow.

Aragonite is the first to precipitate when water levels are high. As evaporation proceeds, Mg becomes more concentrated resulting in the precipitation of Mg-calcite, dolomite and finally sepiolite.

Sample 1-2

Image (photo left) showing aragonite matrix, a primary dolomite layer, and sepiolite clay in the pore space.

The dolomite layer ranges in thickness from 20mm to 100mm and occurs on unaltered crystals of bladed aragonite that do not contain dissolution surfaces and are not cut by replacive rhombs of dolomite, indicating that the dolomite is primary and not a secondary product of digenesis. Within the dolomite, layering is visible that wraps around aragonite crystals.

Sepiolite forms a layer 2mm thick and represents an evaporative stage, indicating a period of arid climate or no water flow.

Ca-Mg-Sr of Travertine Carbonates

Plot shows calcium-magnesium-strontium (x10) ratios for travertine carbonate minerals aragonite, calcite, and dolomite

X-Ray Diffraction pattern confirming the existence of aragonite, Mg-calcite, and Dolomite.

SEM Images showing fibrous sepiolite. Individual fibers are 15mm wide and up to 500mm long.

ARM, NRM, magnetic susceptiblility, and SIRM were measured for travertine samples 2-1A, 1-2, 2-1B, 2-2, and 7-1 in order to potentially characterize the magnetic mineralogy and describe the stability and/or orientation of magnetic remanence carried by the samples. Results confirm that the samples contain magnetic material and the primary mineralogy indicated is magnetite. Measurable remanence and stable magnetic directions are also indicated. Lack of orientation of study samples prevents identification of actual magnetic direction(s) but presents opportunities for additional research.

Figure right: SIRM curves for well-behaved samples 1-2 and 2-1B characteristic of magnetite. Samples 2-2, 2-1A, and 7-1 encountered instrumental inconsistencies and did not result in meaningful curves.

Figures below: ARM and NRM demagnetization curves and vector component diagram for sample 2-1A. Consistency of curves and median destructive fields characteristic of fine-grained magnetite. Vector component diagram demonstrates the removal of a singular, stable magnetic direction (not oriented).

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