The paleontological investigations of the Jurassic of Western Thailand,
districts of Mae Sot (Tak-Mae Sot highway, Padaeng Tak and Ban Mae Kut
Luang Zinc mines) and Umphang (Klo Tho), provide age constraints for the
Late Indosinian orogeny, the Paleotethys closure and the timing of the
marine Jurassic inundation of Sundaland. The basal conglomerate of the
Jurassic is derived from the pelagic Triassic Mae Sariang substratum.
Stratigraphy, microfacies and paleontology of the Jurassic marine strata
focus especially on ammonites, bivalves, large benthic foraminifera and
algae. Among ammonites, the Tethyan Catulloceras perisphinctoides
Gemmellaro marks the Upper Toarcian (Aalensis Zone) along the Tak-Mae
Sot highway and Riccardiceras longalvum (Vacek). Malladaites pertinax
(Vacek), Abbasites sp. and Vacekia sp. indicate Middle Aalenian to
lowermost Bajocian in the Padaeng Mine (SE of Mae Sot) and Klo-Tho
(Umphang). Vacekia sp., Spinammatoceras schindewolfi Linares and
Sandoval and Malladaites vaceki Linares and Sandoval indicate Middle
Aalenian to lowermost Upper Aalenian at Ban Mae Kut Luang (NE of Mae
Sot). Among foraminifers, the large benthic foraminifer Timidonella
sarda Bassoullet, Chabrier and Fourcade in the Western Tethys is
indicative for Aalenian-Bajocian times, as characterized in the section
at the Tak-Padaeng Zinc mine and the Klo-Tho Formation near Umphang. The
endemic foraminifer Gutnicella kaempferi characterizes the Pu Khloe Khi
Formation near Umphang. Among bivalves, shallow marine, dominantly
endemic fauna includes Parvamussium donaiense (Mansuy) and Bositra
ornate (Quenstedt), from the Toarcian to the Early Bajocian. A
consideration of the faunal affinity shows that the fauna is partly
endemic with Northern Tethyan (Eurasian) affinity. Crown Copyright (C)
2010 Published by Elsevier B.V. on behalf of International Association
for Gondwana Research. All rights reserved.