GSA 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, Strandline deposits of the Salton Sea, California: An integrated analogue for Triassic fish-part conglomerates of the Newark Basin [abs]: Geological Society of America - Denver Annual Meeting (31 October –3 November 2010).

Helen Malenda at Denver GSAShell beds are commonly preserved in modern and ancient lacustrine rift settings and their taphonomy is well understood, but the accumulation of disarticulated fish parts in strandline settings is poorly understood. Hence, the Salton Sea shorelines are important modern analogs for the buildup of disarticulated fish parts. The Salton Sea accumulations are compared, contrasted and integrated into an interpretation of fish-part beds of the Triassic Newark basin in Pennsylvania.
Salton Sea shorelines consist of beach ridge surface morphology and normal grading from the beach to the backshore. The most common clast components in core samples are barnacles and disarticulated fish parts. The cored deposits are characterized by normal graded beds, but are doubly graded with two clast types within a single depositional bed: First, the barnacles form a normally graded base of each bed, followed near the top of the bed by smaller comingled barnacles and the hydrodynamicly equivalent largest fish parts. Second, the bed top consists of normally graded fish parts, with isolated partially articulated fish fragments present across the beach surface at the Salton Sea.

The composition and structure of the deposits of the modern Salton Sea are comparable to fish kill beds from rare shoreline deposits of the Triassic lacustrine Lockatong Formation. After death, decomposition and bloating of the fish led to flotation. Fish carcasses were driven shoreward by waves, probably storm-generated. The remains were disarticulated and reworked as lag concentrations that are recorded in the double normal grading of the intraformational clasts (barnacle equivalent) and fish-parts. The graded beds record the impact of the storm on the strandline and coeval washover into the associated fluvial systems. Late partially articulated fish fragments found at the top of the Triassic beds and Salton Sea had not degassed and thus settled last.

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Kurt Friehauf - December 2010