Conversation Geology

Group Leader : Dr. Ros Fatihah Muhammad    rosmuhammad@um.edu.my    03-7967 7126   Room No : GB 212 (New Building)

Members     

• Dr. Iskandar Taib                                                                                                                                                                                                   

Collaborator   

• Dr. Nicholas Pearce (University of Aberystwyth, UK)

Research Background                                                                                                                                                                                                    Occurrences of volcanic ash deposits have been recorded in Perak, Terengganu, Negeri Sembilan, Selangor, Kedah and Perak. The closest and likeliest candidate of the origin of the ash is the Toba area in Sumatra. The available “absolute” dates of the multiple Toba eruptions can be summarized as below.

• Youngest uppermost acid tuff layer 9 km South of Parapat (30 000 years)
• Acid tuff at Siguragura (100 000 years)
• Upper acid tuff at Parapat Pass (100 000 years)
• Lower acid tuff at Parapat Pass (1.2 million years)
• Ignimbrite (welded acid tuff) at Tuktuk Siadong (1.9 million years)
• Acid tuff at Bukittinggi, Padang Highlands, West Sumatera (70 000 years)

The Lenggong ash is of utmost importance because it has been identified with the findings of the Tampanian Paleolithic stone tool sites and the 11,000 year-old “Perak Man”. It was previously dated at 31,000 years are corroborated with the age of the uppermost tuff layer near Parapat. More recently, 74,000 years acid ash has been determined from the Indian Ocean and the South China Sea, and has been correlated with “the Toba” eruption. Comparison on the composition of glass shards betweeen tephra found in Serdang with the ones in Peninsular India, Indian Ocean, Toba Caldera strongly support that all of the tephra belong to the 75,000 years Toba eruption. The ash from Serdand was dated at 68,000 year-old. As there were certainly more than one cataclysmic eruption from the Toba area, and at least two other Late Pleistocene volcanic catastrophes had occurred in Maninjau and the Ranau region, the above correlation of age and origin of the acid ash of Peninsular Malaysia, especially that associated with the Tampanian stone tools, are conjectural. Until the results of the K-Ar dating of all samples in Peninsular Malaysia are known, no evidence of the precise date can be given.

The possibility that the Lenggong valley acid ash originated from other Sumatra volcanoes have never been considered. Toba-like cauldrons associated with surficial acid ash deposits are also known from the Bukittinggi area and Ranau. The ~70,000 years Bukittinggi ash could well correlate with the reported 74,000 – 75,000 ages of ash mentioned in the recent articles. More recent ash studies emphasized the significance of the ~74,000 Toba eruption, with ash termed as Youngest Toba Tuff (YTT). The discovery of the wider distribution of YTT indicates a greater ash volume than was previously suspected. Detailed studies on ash found in Malaysia will hopefully contribute to this greater understanding of the paleoclimate of the region. Also, the evidence found in the culture was connected to the migration of human ancestors from Africa by beachcombing the coast of Indian Ocean.

Research Areas

• Identification of source(s) of young volcanic ash found throughout Peninsular Malaysia.
• Dating of the volcanic ash.
• Stratigraphic position and relationship of the various Late Pleistocene Sumateran ash and those from the peninsula.