Sedimentary geology and geochemical approach to determine depositional environment of the Triassic turbidites bearing Semanggol Formation, NW Peninsular Malaysia

Abstract

The current study will provide sedimentary and geochemical characteristics of turbidites bearing part of the Triassic Semanggol Formation (SgF) from NW Peninsular Malaysia. Six localities have been studied for detailed lithofacies analysis around Taiping, north Perak, Bukit Merah, north Perak and Kampung Badak, north Kedah, whereas 12 representative samples have been selected for geochemical analysis. A total of nine lithofacies (Fsg1-Fsg9) have been identified which categorized into four facies groups: I-Conglomerate dominate facies (Fsg1-Fsg2), II-Sand dominate facies (Fsg3-Fsg6), III-Chaotic unit of shale/mudstone-siltstone dominate facies (Fsg7), and IV-Mud dominate facies (Fsg8-Fsg9). Sedimentary facies analysis has resulted in recognition of four major genetic units: (1) Channel-fill complex, (2) Levee or over-bank deposits, (3) Distal lobes, and (4) Mass transport complexes (MTCs). These four genetic units were deposited within three proposed laterally contiguous depositional environments which are: (1) inner-fan channel-fill complex, (2) mid-fan levees or over bank complex, and (3) outer-fan distal lobes. The Semanggol Formation turbidites system is considered as a multiple-sourced, shelf-fed, Type III, low efficiency, mixed sand-mud rich depositional system. Multiple geochemical indicators (V/(V+Ni),V/(V+Cr),V/Cr, Sr/Cu, Ce∗, Eu∗ etc) have been utilized which show geochemical anomalies trend increases stratigraphically from bottom to top and corresponds to an upward deepening of depositional environment.