Print this pageSedimentology of Miocene Mixed Siliciclastic-Carbonate
Systems, East Java, Indonesia: Implications for the Tectonic Evolution of
Southeast Asia
Jennifer Tang, University of
Wisconsin-Madison, Department of Geology & Geophysics, Madison, WI, [email protected]
The East Java Basin (EJB), Java, Indonesia, lies on the southeastern
Sunda Shelf directly north of the present Java Arc. It has a uniquely complex tectono-stratigraphic
history that challenges conventional basin models: Early-Middle Miocene
compression from the rotation of Borneo to the north and the subducting plate to the south precludes extensional backarc basin and loaded retroarc
foreland basin models. This period of
compression introduced siliciclastics to the shallow
carbonate system and generated the mixed siliciclastic-carbonate
Tuban Formation and the quartz-rich Ngrayong Formation.
Subsequent Plio-Pleistocene uplift exposed
large sections of this Miocene sequence, which presents a unique opportunity to
correlate subsurface 2D seismic and well-log interpretations of the succession
with sedimentologic, petrographic,
and isotopic analyses of outcrop samples. Preliminary seismic interpretations
image Miocene clinoforms that prograde
from the north and the south, which suggests a mixed provenance and changing
drainage patterns. These clinoforms occur at a seismic scale of 300 ms, and their
interpretation in the literature ranges from tidal deposits to contourites, indicating the sustained confusion. This
project’s integrated approach will examine and map in detail the provenance, paleocurrent directions, seismic architecture, age
distribution, lithofacies, and environmental facies of the Tuban and Ngrayong clinoforms. The tectonic, stratigraphic,
and paleoclimatic implications derived from these
results will clarify the impact of Miocene compressional
tectonics on the geologic evolution of Southeast Asia and the supply of
sediment to the EJB as well as modify tectonic reconstructions and basin models
beneficial to the 
scientific
and economic exploration
of Java.