SVP logoKutztown logoStrandline deposits of the Salton Sea, California: An integrated analogue for Triassic fish-part conglomerates of the Newark Basin

Malenda, H. Fitzgerald, Simpson, Edward L., Szajna, Michael, Fillmore, David L., and Hartline, B.W., 2010, Depositional setting of fishpart sandstones and conglomerates: A taphonomic interpretation of a rare lacustrine strand line: Society of Vertebrate Paleontology 70th Annual Meeting (October 12, 2010).

Helen Malenda at Denver GSAFish parts preserved in sandstones and conglomerates were recovered from the Triassic Lockatong Formation of the Newark Supergroup. Data recovered from this unique lacustrine strandline setting were examined using sedimentologic and taphonomic methods to accurately interpret conditions that caused (permitted) accumulation.

Within the Lockatong Formation, reoccurring Van Houten cycles are subdivided into three divisions (D): lake transgression (D1), high-stand (D2), and regression or lowstand facies (D3). The Triassic fish-part sandstones and conglomerates are composed of disarticulated skeletal remains of multiple fish species.

The fish-part sandstones and conglomerates occur at the transition from D1 to D2 and are found above a fluvial intraformational conglomerate composed of diverse mudstone clast types derived from the underlying D3. Fish-part sandstones and conglomerates occur as continuous or lenticular graded beds. Normal graded beds are prevalent and consist of both sedimentary clasts and disarticulated fish parts. Within a bed, the clasts and fish parts do not grade synchronously due to density differences. Either wave ripples or current ripples cap the graded beds, indicating shallow water deposition. In addition, large fish pieces associated with rooted mudstones can be present in lieu of ripple facies, indicating subareal exposure. By using the fish kills in the Salton Sea as a modern taphonomic analogue we propose that a mass kill of Triassic fish species took place in the lacustrine Lockatong Formation. After death, decomposition and bloating of the fish led to floatation. Fish carcasses were driven shoreward by waves, probably storm-generated. The remains were disarticulated and reworked as lag concentrations that are recorded in the normal grading of the sediments and fish part clasts. The intermixing of interformational clasts and fish parts reflects the impact of the storm washover into the associated fluvial systems

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Kurt Friehauf - December 2010