Resumen

PEREZ-CRUZ, Ligia et al. Rock Magnetic and Geochemical Characterization of the Paleogene Carbonate Sequence in the Tekax Borehole, Yucatan, Mexico. Bol. Soc. Geol. Mex [online]. 2024, vol.76, n.3.  Epub 31-Dic-2024. ISSN 1405-3322.  https://doi.org/10.18268/bsgm2024v76n3a010324.

Formation of carbonates involve an interplay of processes, including climate, ocean circulation, marine organisms, sediment sources, transport, deposition and diagenesis. The Yucatan peninsula is characterized by a thick carbonate sequence, which has been studied by geological-geophysical surveys and drilling. Characterizing carbonate systems remains an important yet complex undertaking. Here, results of a magnetic susceptibility and X-ray fluorescence geo-chemical study are used to characterize the Paleogene carbonate sequence in the Tekax borehole of the Chicxulub Drilling Program. The carbonate sequence is ~222 m thick, formed by limestones, dolomites, carbonate breccias and evaporites. Changes in Si, Ca, Fe, Mg, Al, Ti and magnetic susceptibility correlate with lithology downcore. The Ca contents vary through the sequence with a trend around 24% and low discrete values. The upper unit shows higher Ca contents. The Si contents vary downhole, between about 0.03 to 38 %. The carbonates show weak magnetic susceptibilities associated with diamagnetic and paramagnetic minerals, characteristic of carbonate sediments and reduced terrigenous input. Magnetic hysteresis shows fine grained low coercivity magnetite and titanomagnetites, with PSD and MD domain states. Six units are identified through the lithological column. The carbonate sequence shows effects of varying dissolution, fracturing and dolomitization. The lower carbonate unit above the breccia contact shows evaporites, with gypsum and anhydrites.

Palabras llave : Chicxulub crater; Tekax borehole; Yucatan peninsula; Paleogene carbonate sequence; Magnetic susceptibility; X-ray fluorescence.

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