Morphological abnormalities observed in the species Ammobaculites texanus cushman and paleoenvironmental implications

• Published in: Revue de micropaléontologie Vol. 68; p. 100444
• Main Author: Orabi, Orabi H.
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 01-10-2020
• Subjects: Agglutinated foraminifera; Cretaceous; Kharga Oasis; Morphological abnormalities; Kharga Oasis; Cretaceous; Agglutinated foraminifera; Morphological abnormalities
• ISSN: 0035-1598; 0035-1598
• DOI: 10.1016/j.revmic.2020.100444

The morphological abnormalities caused on the agglutinated foraminifera Ammobaculites texanus CUSHMAN extracted from the Lower Kharga Member of the Dakhla Formation (Upper Maastrichtian) deposits may be caused due to environmental factors such as high organic flux, high terrigenous input and low salinity as indicated by the presence of Ammoastuta together with A. texanus agglutinated foraminifera, which suggested hyposaline environments.
The deformations described in this work are several types of morphological abnormalities, including irregular chamber shape (lobate peripheral outline), abnormal size or shape of the last chambers, high spire giving a spiroconvex test and irregular coiling, and additional chambers (elongated axes of rotation). Some studied species of A. texanus show compaction and the collapse of the inner microgranular layer, the compaction indicates the binding of quartz grains with a deformable substance before cementation.