MORFOSTRATIGRAFI  TUF IGNIMBRIT MANINJAU   DI NGARAI  SIANOK,  DUSUN BELAKANG BALOK-BUKITTINGGI, SUMATERA  BARAT

Soemantri Poedjoprajitno

doi:10.33332/jgsm.geologi.v18i3.264

Authors

Soemantri Poedjoprajitno Pusat Survei Geologi Author

DOI:

https://doi.org/10.33332/jgsm.geologi.v18i3.264

Abstract

The ignimbtrite plato of Sianok Valley at Belakang balok Village was produced by two periods of Maninjau volcanic eruptions. The two eruption periods are separated by fluvio volcanic deposits, consisting of very qoarse sand and conglomerate. The two periods pyroclatic deposits at containing pumice and locally several coal.Â These pyroclatic deposits were faulted and formed terrace morphology. The Sianok Valley is considered as an effect of the reactivation of basement fault throughting the ignimbrite deposits.

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Keywords:morphostratigraphy , Maninjau pumice tuf, terrace, fault, plato

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