Biometric Analysis of Miogypsinidae and their Taxonomic Significance from Azkand Formation (Oligocene-Miocene) in Kirkuk area, Iraq

Ahmad Muhammed, Qahtan

	Biometric Analysis of Miogypsinidae and their Taxonomic Significance from Azkand Formation (Oligocene-Miocene) in Kirkuk area, Iraq
Tikrit Journal of Pure Science
Article 1, Volume 13, Issue 1, 2008, Pages 175-190
Author
Qahtan Ahmad Muhammed
Abstract
The investigation is based on a well exposed and subsurface stratigraphic succession of bioclastic limestone in Kirkuk area. These sequences were deposited in a shallow open marine environment during Chattian to Aquitanian. Test of larger foraminifera Miogypsinidae are abundant in the lower and upper parts of this sequence. The internal morphology of the Miogypsinidae test has been thoroughly investigated. Biometric analysis on Miogypsina reveals that the oldest species of Miogypsina are present in the lower part of the Azkand Formation in the Khabaz well-3 and Qarah Chauq Dagh sequence represented by Miogypsinoides complanata and Miogypsinoides formosensis. The early Miocene association of the Miogypsina s.s. is often accompanied by associations of Miogypsinoides. Most of these are close to Miogypsinoides bantamensis. On the basis of the mean of embryon size ; two types of assemblage of Miogypsinoides could be distinguished in the Early Aquitanian sediments. Type I with the smaller embryon (D1 = 110-125 μm) and Type II with the larger embryon (D1 = 210-230 μm). The data set for the main lineage of Miogypsina exhibit a distinct overall change in morphology of the nepiont, which change is in agreement with the principle of nepionic acceleration as defined by[1]. Another abundancy of the Miogypsina s.s. has occurred in the upper part of Azkand Formation with mean values of (X) between (9-11) represented by Miogypsina gunteri-tani, which occurred simultaneously with Miogypsinoides bantamensis with their mean values of (X) between (10-13).

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