Date of Defense

12-20-2006

Department

Geosciences

First Advisor

Dr. G. Michael Grammer

Second Advisor

Dr. William B. Harrison III

Third Advisor

Dr. Robb Gillespie

Abstract

Phylloid algae were common reef builders during the Paleozoic. They are known to form well-developed hydrocarbon reservoirs in many parts of the world. Current dogma concerning the formation of phylloid algal mounds is that they formed in-situ primarily through constructional processes. These processes included sediment baffling and binding by algae and various other organisms, coupled with pervasive early submarine cementation. Most models suggest deposition along a shelf margin or outer parts of a distally steepened ramp resulting in a generally strike-elongated distribution. Recent observations of phylloid algal mounds exposed along the San Juan River in Utah have shown that 10-12m amplitude mounds are distributed in a near sinusoidal pattern suggesting that they may have formed under the influence of wave- or tide-generated ocean currents. Tide-generated currents in modem environments often pile plates of the modem algae Halimeda into dunes or sand waves along the sea floor with a similar near-sinusoidal distribution.

Determining the conditions under which these mounds initiated and grew may have important implications to exploration concepts devised for algal reservoirs. High energy, current-emplaced mounds, may be aerially limited in the subsurface, and may trend preferentially either along strike (e.g. wave currents), or conversely along dip (e.g. tidal currents). Constmctional mounds, in contrast, may have formed in much broader areas across an entire shelf or platform. Relative percentages of primary matrixmud (generally lower in current-influenced mounds) may also affect reservoir quality, and should be considered at both exploration and production scales.

Access Setting

Honors Thesis-Campus Only

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