--> Abstract: Hummocky Strata in Deep-Water "Intraformational Conglomerates"/Brecciolas Overlying Regularly Bedded Hemipelagic Hatch Hill (U. Cambrian) Limestones: Products of Tsunami Waves?, by G. M. Friedman and J. E. Sanders; #90954 (1995).

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Abstract: Hummocky Strata in Deep-Water "Intraformational Conglomerates"/Brecciolas Overlying Regularly Bedded Hemipelagic Hatch Hill (U. Cambrian) Limestones: Products of Tsunami Waves?

G. M. Friedman, John E. Sanders

The thin-bedded hemipelagic limestones of the Hatch Hill Formation (U. Cambrian) of the Taconic Sequence in eastern NY are overlain by distinctive lenticular intraformational ("flat-pebble" or "edgewise") conglomerates or "brecciolas." Many of the "pebbles" in these conglomerates/brecciolas evidently were derived from the digging up and local transport of nodular bodies of carbonate that may have become segregated as isolated "nodules" during early diagenesis of these deep-water carbonates. The conglomerates form convex-up lenses up to 2 m thick and at least 10 m across. Their bases are flat surfaces or fillings of local channels cut a decimenter or so into the underlying nodular zone. Siltstone strata lacking carbonates drape over the convex-up lenses.

We interpret these lenses as being analogous to hummocky strata, which have been ascribed to the combined effects on shelf sediments of waves and currents. The waves involved in the origin of these deep-water, off-shelf brecciolas probably were tsunami.

AAPG Search and Discovery Article #90954©1995 AAPG Eastern Section, Schenectady, New York