Abstract
During detailed interpretation of seismic survey JNOC88 and some AGSO lines in the northeastern part of the Offshore Canning Basin (Offshore Fitzroy graben and part of the Rowley sub-basin), different scales of valleys and channels in the Albian to Palaeocene succession were noted. The sediments in the area of valley/channel development are dominantly calcilutite, marl, clay, silt, and fine sand deposited in shelf-to-slope water depths. The most evident valleys are associated with the Upper Cretaceous seismic event C6-2 and the Base Tertiary seismic event C13-1, with dominant north-south and northeast trends that are different from the northwest dip of the paleo-slope and -shelf. Small channels developed between C6-2 and C13-1 with an estimated northwest trend. We classify these channels and valleys into four categories: Type 1 to 3 valleys and Type 1 channels according to their scale, morphology, and related geological processes. Among them, Type 1 and Type 2 valleys are associated with the low point of the third-order global sea level curve, whereas the smaller-scale Type 1 channels seem to be associated with flooding surfaces. We suggest that submarine erosion by bottom current, contour current, or slumping formed the Type 1 valley, and similar processes in shallow water formed the Type 2 valley. The Type 3 valley is regarded as a valley cut into a lowstand fan.
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