Micropaleontological Analysis of the Stratigraphic Relationship between the Bentang Formation and the Halang Formation in Margajaya Village, Sukadana Sub-district, Ciamis Regency, West Java Province

Abstrak

The Halang and Bentang Formations exposed in the Margajaya area, Sukadana District, Ciamis Regency, West Java, represent contrasting depositional systems within the Bogor Back-Arc Basin. This study aims to analyze the stratigraphic relationship between the two formations using planktonic and benthic foraminiferal micropaleontological analyses. The research methods included field observations, rock sampling, micropaleontological preparation, and foraminiferal identification. Relative age determination was based on the First Appearance Datum (FAD) and Last Appearance Datum (LAD) of planktonic foraminifera following the zonation scheme of Blow (1969), whereas depositional environments were interpreted using benthic foraminiferal bathymetry according to Barker (1960). The results indicate that the Halang Formation was deposited during the Middle–Late Miocene (N14–N16) within an upper bathyal deep-marine environment and is characterized by turbiditic sandstone and siltstone deposits. In contrast, the Bentang Formation, which is dominated by claystone lithology, was deposited during the Late Miocene (N16) within outer to middle neritic shallow-marine settings. The overlap in relative age between the two formations, combined with contrasting depositional environments, suggests a lateral facies transition within the basin system. This condition indicates a possible interfingering relationship between the Halang and Bentang Formations during the Late Miocene.