A Submarine Fan Model for  the Sigaboy Formation,

Davao Oriental: Implications to the Reservoir Potential

of  Turbidite Deposits in the Agusan-Davao Basin

 

Karlo L. Queano

Mines and Geosciences Bureau (Central Office)

North Avenue, Diliman, Quezon City 1104

 

 

Abstract

 

            The Sigaboy Formation  outcropping in  Pujada Peninsula, Davao Oriental  consists of   submarine channelized and unchannelized deposits laid down by low and high density turbidity currents.  This formation is derived from an ophiolite suite,  associated sediment  carapace   and    metamorphic rocks and is associated with volcanism based on the  tuffaceous character of some of the deposits.   Facies defined in these rocks studied from  Sitio Talisay in the north to   Barangay Lavigan in the south  points to a possible submarine fan model for the formation.

 

The stacking  pattern of the succession in the studied sector of  the Sigaboy Formation formed  vertical and lateral continuity of sandy and gravelly facies whose possible equivalence in the adjacent Agusan-Davao Basin could  attract explorers to consider them as potential reservoirs.  However, porosity studies of the different facies of the  turbidite system  from various stratigraphic intervals clearly show that  porosity is very low. This is due to  the   unstable mineralogy,   diagenesis,  poor sorting  and  the unfavorable geologic setting of the Sigaboy Formation.