Geological and structural studies conducted in Caramoan Peninsula reveal the presence of
flysch and olistostrome units in the eastern part of the peninsula. Paleontological analyses of the flysch sequence and the matrix of the olistostrome yielded a latest Middle Eocene to earliest Late Eocene (Nannofossil zone NP17- NP18) age for the units. The olistostrome is characterized by exotic blocks of varying lithologies and ages in which the youngest olistoliths recognized are the late Bartonian-early Lutetian Iimestones and nummulitic conglomerates. Detailed investigations show that the flysch and the olistostrome form a continuous sequence in which the olistostrome represents its upper part.

Structural analysis revealed that the Tabgon Flysch and Ragas Point Olistostrome were limited by left lateral strike slip faults. Syndepositional normal faults could also be observed to be affecting the flysch and olistostrome. This indicates that the strikeslip faulting could have resulted in the formation of transtensive basins which received the deposition of the flysch and olistostrome. This tectonic phase postdates the formation of the Middle Eocene Guijalo Limestone in Caramoan Peninsula because the limestone occur as olistoliths within the olistostromes.

These observations reveal an important tectonic episode during the latest Middle Eocene to earliest Late Eocene contemporaneous with the deposition of the flysch and olistostromes. This phase most probably corresponds to the change in motion of the Pacific Plate during the Middle Eocene which has resulted in the left lateral strike-slip faulting in the eastern Philippine Mobile Belt. The northwest-southeast trending fault zone most probably represents the trace of a paleo-Philippine Fault affecting the Philippine Mobile Belt during this time.