@phdthesis{oai:air.repo.nii.ac.jp:00005803,
 author = {RENDY},
 month = {Sep},
 note = {The East Java Basin is one of Indonesian Cenozoic petroleum basin with fair
production for over a century. The East Java Basin is extensively filled with carbonate
and siliciclastic sedimentary rock since Eocene. Several studies exhibit comprehensive
explanation of the depositional system of the East Java Basin during Cenozoic, most of
the age of the sedimentary rock has not been well-dated and only a few researchers had
conduct precise age dating. Biostratigraphy of several exploration wells in the East Java
Basin also had been studied for both planktic foraminifera and calcareous nannofossil
by. However, the areas studied are limited and some of the results have not indicated
the high resolution. Based on that problem, the calcareous nannofossil biostratigraphy
of LSM-1, JTR-1, BEL-1, TPN-1, KTB-1, and NGB-1 wells located in the onshore East
Java Basin, Indonesia was studied in detail to clarify the age distribution of sedimentary
rocks and the history of basin evolution of the onshore East Java Basin.
Total of 678 cutting samples was selected every 20m interval and processed using
the smear slide preparation method. All smear slides were examined under an Olympus
binocular polarizing microscope and quantitative analysis was employed. Graphic
correlation also applied to derive precise biostratigraphic correlation.
A total of 71 species from 26 genera of calcareous nannofossil were determined
in the seven wells, most of the specimens are found at moderate to good preservation.
Reworked specimens from early Miocene series are sometimes observed in the Pliocene
series. The age assignment based on 27 calcareous nannofossil datum were obtained as
follow: DDR-1 corresponds to NN3-NN15 of the early Miocene to the early Pliocene.
NGB-1 are appointed to NP23 to NN7 of the early Oligocene to the late Miocene. KTB-
1 is assigned to NP25-NN16 of the late Oligocene to the late Pliocene. TPN-1 covers
NN7-NN16 of the middle Miocene to the early Pliocene. BEL-1 is estimated as NN3 to
NN5 of the early to middle Miocene. of JTR-1 is assigned to NP23-NN4 of the early
Oligocene to early Miocene. And the last, LSM-1 is estimated corresponding to NP25-
NN16 of the late Oligocene to early Pliocene.
The result from the biostratigraphic correlation analysis indicates that a total of
four significant unconformities are traceable in the sequence between the Oligocene and
the Pliocene in this area. The Oligo-Miocene Unconformity (OMU) is situated in the
Oligocene/early Miocene boundary. The OMU, which is traceable to all wells, is
characterized by the missing of the interval from NN1 to NN3 zone of the early Miocene.
The Mid-Miocene Unconformity (MMU) is correlated to the early-middle Miocene
which is found only in KTB-1 and NGB-1, since the calcareous nannofossil zone of
NN6 is not present in these wells. The late Miocene Unconformity (LM1), which is
characterized by the missing of the interval NN8 of the early late Miocene is traceable
to KTB-1, DDR-1, and TPN-1. The Mio-Pliocene Unconformity (MPU), which is the
biggest unconformity found in the study area, is situated in the lower Pliocene base. In
this area, the lower Pliocene NN14 sediment is distributed above the MPU. The time
gap of the MPU is the biggest in LSM-1 and BEL-1 located in the north western area.
The interval, NN6 to NN13 of the middle Miocene to the lowest Pliocene is missing in
LSM-1, and NN8-NN13 is also missing in NGB-1.
Based on the bio-lithostratigraphic correlation analysis, the results indicate that
the sediment above the OMU is situated relatively in the centre of the studied area (BEL-
1 and TPN-1). In contrast with sediment of the Miocene above the MMU and LM1
which are concentrated in the central to south-southeast area, the location of Pliocene
sediment above the MPU moves to the north and north-western area. The depositional
pattern also demonstrates that the majority of sandstone and limestone deposition is
linked to the distribution of unconformities, which are located just above them. During
the middle to late Miocene, there is no evidence of sedimentation in the north and
northwest. The thickest sandstones, which are reservoir rocks of this oil field, is
correlated to the early Pliocene Low System Tract and Transgressive System Tract
above the MPU.
The stratigraphic series and unconformities detected in the study area show a good
correlation to the global climatic events and tectonic evolution. The Oligocene Series is
correlated to the late Oligocene warm event. The Miocene Series unconformably overlie
the Oligocene Series and fit to the Mi 1 cooling event. The early Miocene series above
the Oligo-Miocene Unconformity is correlated to the Mid-Miocene climatic optimum
event. The Mid-Miocene Unconformity may be correlated to the cooling events Mi3 or
Mi4 just after the Mid-Miocene Climatic Optimum. The middle-late Miocene sequence
between the Mid-Miocene Unconformities and the Late Miocene Unconformity 1 is
considered a single transgressive-regressive cycle. The Late Miocene Unconformity 1
is correlated to the cooling event of Mi5. The Mio-Pliocene Unconformity is correlated
to the Messinian Salinity Crisis event and RMKS Uplift. The upper-lower Pliocene
series above the unconformity is correlated to the mid-Pliocene Warm Period. These
results indicate that the stratigraphic evolution and formation of the unconformities
detected in the East Java Basin during upper Cenozoic are strongly influenced by
eustacy sea-level changes, and then by tectonics, especially in the late Miocene to the
Quaternary.},
 school = {秋田大学},
 title = {Upper Cenozoic Calcareous Nannofossil Biostratigraphy and Basin Evolution of the East Java Basin Indonesia},
 year = {2022}
}