麻豆传媒

听

B. Sc. Honours Thesis

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Two sections of the Halifax Formation, Meguma Group (Lower Paleozoic) at Ovens Park, Nova Scotia, were examined for sedimentary structures, grain size and facies associations.

Interpretation of the depositional processes and the sedimentary environment was attempted in view of models of sediment gravity flow and deep-sea fan deposition.

The depositional environment is in the mid-fan area of a deep-sea fan and the beds were viewed as products of turbidity flows. The recognition of Bouma (1962) Ta, Tb, and Tc equivalents (Facies A, B, and C respectively) and the presence of fine grain sediment (very fine sandstone to mudstone) suggests that the processes responsible for producing sequences with Bouma (1962) division characteristics are not restricted to sand-size sediments. The presence of beds with undulose, wavy bedding planes and beds with plane bedding suggests that there may be a distribution of "power' within turbidity flows. The wavy, undulose bedding results from the rate of deposition decreasing less rapidly with time than the rate of bed load transport. The term "low power flow" is used to distinguish strata deposited under waning flow conditions, low velocities and low sediment concentrations; the term "high power flow", is used to distinguish strata deposited under higher velocities and higher sediment concentration than strata deposited under low power flow conditions.

Facies descriptions were related to descriptions of recent deposits of deep sea fans. Facies associations, as defined by sequence analysis, and variations in facies associations are believed to reflect changes in the power of the turbidity flow; the change in the power of the turbidity flow, the grain size and sedimentary structures recognized in each facies reflect the depositional environment of the turbidite unit.

Pages: 105
Supervisor:听 D. J. W. Piper