On the first day of the fieldtrip, the AAPG UPN SC team started its activities around the Islamic Center of Balikpapan Mosque. The member has done observations of outcrops while lecturer provide an introduction to the Kutai Basin and its constituent Formations, as described above. To complete the participants knowledge, each gets a pocket book that includes a review of the fieldtrip within the next few days. At this stopsite we observed lithologies of sandstone, claystone, organic shale and coal which contained various sedimentary structures including bedding, parallel lamination, wavy, lenticular, and flaser, nodule of iron oxide, and burrows. Types of delta, fluvial processes and its products are also discussed. Activities on this stopsite end with a photo together.
On the second day, fieldtrip is more about coal, starting from coal formation, quality and classification, as well as its sedimentation environment and petroleum system related to delta facies and with its mechanism. Not only that, further the tremendous CBM potential which is owned by the ancient Mahakam Delta has been discussed here. At least two stopsite successfully visited along the journey from Balikpapan to Samarinda, involve the outcrop of coal seam, the unconformity, and includes the aspects in the petroleum system, such as geological structure and stratigraphy as traps, coal and other organic shale as source rocks, sandstone as the reservoir, shale as the caps rock, and the fault and fracture as the migration route, as well as its association with each age of its deposition. Although there is one stopsite, the seepage gas that failed to visit due to very bad weather. But the discussion not only stops in the field, but along the way in the bus, participants and counselors are very active in discussing various matters.
On the third day, Batu Putih locality shows a 150-200 meters tilted succession of shallow marine to shelf break deposit. In the top of the hill, the limestone outcrop provides an opportunity to study the carbonate bank facies especially in the close proximity to the proto-Mahakam Delta. The carbonate unit shows a limestone package interbedded with fossiliferous shale and marl (rich in encrusting bioclasts). This succession is interpreted as patchy reef, appear in life position before buried rapidly (Wilson et al., 2005; Marshall et al., 2015) (Fig. 2.6b). This carbonate facies is interpreted to be growth in the shelfal area, which probably within a far distance from the siliciclastic feeder system (e.g. in the shelf edge area). After the Batu Putih stopsite, the journey continues towards the main stadium Palaran Samarinda. There are several large-dimensional outcrops, which can be observed succession of ancient Mahakam delta deposits, as well as gradations of depositional environmental changes. The Stadion Utama is located in the Southern side of the modern Mahakam River (Samarinda seberang area). The 250 meters dip parallel outcrop is exposed on both sides of the main access toward the Stadion Utama Palaran. The outcrop display several repetition of deltaic parasequences and present a clear view of the deltaic facies changes from the fluvial dominated upper delta plain, to the strongly tidal influenced lower delta plain and delta front. This outcrop provides excellent opportunity to learn about the ideal deltaic succession without any significant erosional disturbance and also to observe various external controls on the depositional architecture, included morphology, biogenic and oceanographic aspect in the lower distributary and delta front area. The deltaic succession in the lower part shows a sharp based contact typical to the erosional boundary (rip up clast, lag deposit), followed by channel filled deposit comprises of coarse to medium grained sand with through cross-bedding that gradually change into high angle to low angle planar cross-bedding Finally, the event officially closed at the hotel in Balikpapan, therein concluding the knowledge gained from the fieldtrip, integrating one stopsite with another, and the handover of momento as a symbol of gratitude to the lecturers. Finally, the whole series of field trips went great, all participants in good health, and the knowledge gained was very useful and irreplaceable. The next day, the fieldtrip participants returned home to Yogyakarta safely.