Study of Microfaunistic of foraminifera in Holocene surface sediments of the Asalouyeh area – persian Gulf

Subject Areas :

معصومه Molaei ¹ , معصومه Sohrabi-Molahoseini ² , سارا Kahrobaei-Monfared ³

1 - کارشناس ارشد چینه و فسیل شناسی، گروه زمین شناسی، دانشگاه آزاد اسلامی، واحد اسلامشهر
2 - استادیار گروه زمین شناسی، دانشکده علوم پایه، دانشگاه آزاد اسلامی، واحد اسلامشهر
3 - دانشجوی کارشناسی ارشد تکتونیک، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات تهران

Received: 2016-09-07 Accepted : 2016-09-07 Published : 2012-12-21

Keywords: microfounistic, bentic foraminifera, Holocene, surface sediments, Asalouyeh,

Abstract :

Considering the economic importance of this region, for the first time some studies on superficial sediments(deposits) foraminifera were carried out in this region. Purpose of these studies was to investigate effect ofenvironmental changes on foraminifera and to use them as bio-indices in diagnosis of contaminations. In thestudies regarding foraminifera, 12 genus and14 species were identified and foraminifera with hyaline lime shellhad the greatest frequency. The main identified collection is: Ammonia beccarii Linne.And the speciesaccompanying this collection are: Amphistegina lessonii, Elphidiom crispum, Elphidiom craticulatum,Triloculina tricarinata, Quniqueloculina seminulum, Ammonia parkinsoniana, Eponides repandus, Dendritinaambigua After foraminifera with hyaline lime shell, foraminifera with selenosis progeny shell were ranked nextin terms of frequency. However, foraminifera with agglutinated shell were not observed in this region. Ingeneral, the obtained results from mineralogy studies on deposits of the ebb and flow area is the evidence thatmajor part of the sediments are related to continental environment of the detrital deposit type. In sectionecological studies, water's physicochemical factors are measured. Based on these studies, increase of water'stemperature and salinity results in decrease of solution oxygen in water and water's acidity degree. However, ingeneral, water's acidity fluctuation is slight and insignificant. The most important physicochemical factoraffecting development of foraminifera is amount of solution oxygen in water which controls their frequency anddiversity. Precipitation of oil carbohydrates and other contaminators produced by petrochemical activities in theregion ruins the bio-environment, reduces solution oxygen, and gives rise to release of heavy and toxic metals(mercury and lead) from solid state to liquid which leaves numerous negative effects on marine andenvironmental ecosystem