Publications

Discerning the role of tectonics and eustasy in stratigraphic records is not trivial, especially in Indonesia, where most of the sedimentary basins underwent active tectonic stages in their geologic history. Constructing a conclusive geological synthesis is sometimes quite challenging, considering the perplexity in discriminating eustatic signals from tectonic signals in sedimentary successions. One way to differentiate the role of tectonics and eustasy is by correlation to a relatively stable tectonic region, or an independent reconstruction of global sea level fluctuation. This approach however requires a high resolution chronostratigraphic framework, which sometimes cannot be constructed using biostratigraphy data alone. This paper aims to review and demonstrate the use of strontium isotope stratigraphy to address the aforementioned problem. The use of strontium isotope as a stratigraphy tool relies on the fact that strontium isotopic ratio of 87Sr/86Sr in the ocean is homogeneous. This characteristic arises from the duration of the residence time of strontium in the ocean, which is longer than the cycle of sea water. Stratigraphers utilize this characteristic to correlate stratigraphic strata across distant region and to determine the age of stratigraphy intervals, by calibration of strontium isotopic ratio measurements to a known strontium curve for certain time interval. A case study from the Appalachian Basin is presented in this poster. The case study shows how strontium isotope stratigraphy is used as a framework to correlate a major unconformity in the Appalachian basin to a sea level curve reconstruction.