Event Title

Evidence for sustained hyperpycnal flow in the Upper Devonian Trimmers Rock Formation- Watts Twp., PA

Presenter Information

Zachary Zega

Faculty Advisor

Dr. Jennifer Elick

Start Date

24-4-2018 5:00 PM

End Date

24-4-2018 6:00 PM

Description

The Upper Devonian Trimmers Rock Formation (Watts Township, PA) represents a progradational marginal marine environment within a foreland basin, however, it lacks the stacking pattern of a deltaic environment. In order to identify other possible processes for deposition, 55 m of rock were measured and described. This data represents a number of nearshore marine facies influenced by inertial and gravity driven controls, namely turbiditic systems and deposits that exhibit evidence of intermittent and sustained hyperpycnal flow. Though wave and tidal activity do influence some of the facies. Deposition is dominated by inertial and density driven flows and characterizes the section more appropriately than a standard wave or tide-controlled deltaic facies model. Hyperpycnal deposits are a newer topic of study and are crucial to understanding how sediment may have been transported in ancient foreland ramp systems associated with smaller river systems. Distal ramp turbidites at the base of the section are represented by laminated sands fining-upward into siltstones showing partial Bouma sequences. The poorly mixed facies in the middle of the section are represented by more episodic erosional surfaces influenced by traction and fallout processes associated with quasi-stable and waning plumes of sediment-laden hyperpycnal flow. This environment gradually grades into massive sand deposits with some laminations and organic matter followed by surfaces strongly influenced by frictional processes also associated with hyperpycnal flow. This is a new way of interpreting the Trimmers Rock Formation and may explain the lack of strong deltaic features in PA.

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Apr 24th, 5:00 PM Apr 24th, 6:00 PM

Evidence for sustained hyperpycnal flow in the Upper Devonian Trimmers Rock Formation- Watts Twp., PA

The Upper Devonian Trimmers Rock Formation (Watts Township, PA) represents a progradational marginal marine environment within a foreland basin, however, it lacks the stacking pattern of a deltaic environment. In order to identify other possible processes for deposition, 55 m of rock were measured and described. This data represents a number of nearshore marine facies influenced by inertial and gravity driven controls, namely turbiditic systems and deposits that exhibit evidence of intermittent and sustained hyperpycnal flow. Though wave and tidal activity do influence some of the facies. Deposition is dominated by inertial and density driven flows and characterizes the section more appropriately than a standard wave or tide-controlled deltaic facies model. Hyperpycnal deposits are a newer topic of study and are crucial to understanding how sediment may have been transported in ancient foreland ramp systems associated with smaller river systems. Distal ramp turbidites at the base of the section are represented by laminated sands fining-upward into siltstones showing partial Bouma sequences. The poorly mixed facies in the middle of the section are represented by more episodic erosional surfaces influenced by traction and fallout processes associated with quasi-stable and waning plumes of sediment-laden hyperpycnal flow. This environment gradually grades into massive sand deposits with some laminations and organic matter followed by surfaces strongly influenced by frictional processes also associated with hyperpycnal flow. This is a new way of interpreting the Trimmers Rock Formation and may explain the lack of strong deltaic features in PA.