Ichnofossil assemblage of Bhuban Formation (Surma Group) from Zuangtui area, Aizawl, Mizoram

Abstract

Bhuban succession of Surma Group (early to middle Miocene) is well exposed in Zuangtui section of Aizawl district of Mizoram and comprises ~40 m thick sequence of alternating sandstone, silt-stone and shale and their admixtures in various proportion. Highly bioturbated rocks of this sec-tion show behaviorally diverse groups of trace fossils. A total of 17 ichnospecies have been identi-fied from this section. These are Cochlichnus anguineus, Diplopodichnus biformis, Funalichnus bhubani, Gordia marina, Palaeophycus striatus, P. tubularis, Planolites beverleyensis, Planolites isp., Psilonichnus upsilon, Psilonichnus isp., Rhizocorallium isp. Type A, Rhizocorallium isp. Type B, Skolithos isp., Teredolites clavatus, T. longissimus, Thalassinoides horizontalis and T. suevicus. These trace fossils represent the record of Skolithos, Cruziana and Teredolites ichnofacies and at places the mixed Skolithos-Cruziana ichnofacies. Teredolites infested log-grounds and the other ichnological evidences indicates that the rocks of Bhuban Formation exposed in Zuangtui area, Aizawl district of Mizoram were deposited under near shore high energy conditions.