Sistem sesar dalam Basalt Segamat: Kajian kes di Kuari Yam Fong

Segamat Basalt erupted in the Early Tertiary during which the Malay Peninsula was considered as tectonically stable. Field studies at Yam Fong Quarry, Kampung Jabi, Segamat indicate that apart from jointing and formation of veins, the basalt here has also undergone lateral and reverse faulting. Based on the relationship of the structures (faults) found here, it is interpreted that the Segamat Basalt has suffered at least two phases of compression, the earlier from eastnortheast followed by east-southeast. Calcite veins are also well developed within certain zones aligned in northnortheast and east-northeast directions. The earlier set of conjugate lateral faults that formed as a result of compression from east-northeast were cut and displaced by the later conjugate lateral fault system, which resulted due to compression from east-southeast. The earlier stress system was responsible for the formation calcite veins. The later stress system was responsible for the formation of another set of conjugate lateral faults and reverse faults. The results of this study indicate that compressional stress was still present in the Malay Peninsula in the post Early-Tertiary when the area was considered as tectonically stable.