ANALISIS SIKLUS SEDIMENTASI ENDAPAN KUARTER DAERAH KABUH, JOMBANG, JAWA TIMUR BERDASARKAN TAFONOMI MOLUSKA

• Main Author: DEWI , FITRIA
• Format: Theses
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/20110
• Institution: Institut Teknologi Bandung

Geomorphology of the study area can be divided into Anticline plain and Anticline morphology unit areas. Fold is main structural geology in the area which has fold axis east – west direction. Stratigraphy of the study area consist of three informal unit stratigraphy from older to younger that are: interbedded sandstone and claystone unit, sandstone unit and interbedded sandstone and tuff. Based on lithology description and taphonomy of mollusca show that sedimentation cycle is affected by sea level fluctuation which is Transgressive System Tract (TST) to Highstand System Tract (HST) then formed Sequence Boundary (SB) when sedimentation break occurred. TST is observed from deposition of interbedded claystone and sandstone with sparse juvenile and mature mollusca, mostly mollusca shell is fragmented, with random orientation and irregular, and not appear of non?fragmented mollusca, also has burrowing structure. Early HST appear in the sandstone with mollusca, juvenile and mature molusca is separately, characterized by high percentage of individual mature specimen separated from a group of younger molusca shell, formed by sedimentation process with high sediment supply. Then HST phase occurs which is deposited sandstone with compact mollusca, juvenile and mature molusca, separately, characterized by mollusca fossil with various random orientation, also contain Globorotalia sp, Cibicides sp, Quinqueloculina sp. In the end of HST is dominantly consist of multiple?event concentrations of compact deposit of fossil and fossil very sparse in upper?part of the sandstone, but Globorotalia sp, Cibicides sp, Quinqueloculina sp are remain appeared. End of HST is deposited sandstone with conglomeratic lens, without foraminifera and mollusca fossil. Changing of this taphonomy mollusca is interpreted as Sequence Boundary (SB). This Sequence Boundary is also supported by lithology changing from Pucangan Formation to Kabuh Formation.