Systematic of Upper Cretaceous Flysch deposits ichnofossils in south of Golbaf, Kerman province

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Article Type:
Research/Original Article (دارای رتبه معتبر)
Abstract:
Introduction

The Cretaceous deposits of Golbaf region are part of the Rhine-Guk-Khana Khatun zone in the stratigraphic-structural belt of Rafsanjan (Dimitrijevic and Djokovic, 1973). In this belt, Cretaceous deposits are divided into shallow to deep facies, and the most complete Cretaceous deposits can be found in the Rhine-Guk-Khan Khatun area (Dimitrijevic, 1973). The studied sedimentary sequence is exposed in the south of Golbaf and southeast of Kerman and its thickness is 147 meters. The age of these sediments is Upper Cretaceous (Coniacian-Santonian). These sediments contain clastic deposits that are gradually and with the same slope on the Lower Cretaceous and Neogene, and the upper boundary of this section is in the form of marl limestone related to MaisTrichtian facies. This section has a lithological sequence of columnar silt, silty sandstone, and shale, which contain fossils and species that have been identified in the debris layers of this section. These fossils are mostly creeping-nutritional or nutritional traces. These fossils are found in shallow to turbidity marine environments, which are well preserved and varied, and their most abundance can be seen in the middle part of this section. In this article, an attempt was made to systematically identify the existing fossils and discuss and examine their behavioral patterns.

Materials and methods

This study includes two stages of field and laboratory operations. In the field operation, after identifying the intended cut and determining the boundaries as well as the beginning and end of the desired cut, the thickness of each layer was measured and examined.  The required information was noted down, and if sampling was done, fossils were taken from the sediments. In the laboratory, after photographing each sample, the characteristics of each fossil, such as shape, size, dimensions and type of preservation in relation to the level of layering, decorations and various components, were identified (Miller, 2007; Seilacher, 2007). Then the trace fossils were classified based on the behavioral status first presented by (Seilacher, 1964) and discussed by (Bromley, 1996) and finally the fossil systematics was written completely.

Results and discussion

Trace fossils are biological constructions in sedimentary environments that are formed by organisms in soft to hard sediments. Trace fossils are biological constructions in sedimentary environments that are formed by organisms in soft to hard sediments. Trace fossils are biological constructions in sedimentary environments that are formed by organisms in soft to hard sediments. Turbidites are generally found as flysch deposits and are considered as deep basin rock facies. These sediments, in expanded patterns, Boma include a series of diverse clastic-mudstone facies (Pickering et al, 1989). On the other hand, trace fossils have complex geometrical shapes that are usually observed with marine and deep pelagic sediments. Since the trace fossils in Golbaf region are widespread and abundant, therefore, in order to achieve turbidite sedimentary environments, based on the data of Archeology It is necessary to combine the archeology data with sedimentological data and structural elements. The rock facies of the studied sequence include The facies are siltstone, silty sandstone, and Chile. In these beds, the amount of sedimentation is low to high. According to the archeological data, diversity and abundance of fossils in the studied sedimentary sequence, on the surface of silty sandstone and siltstone layers, it can be concluded that most of the fossils are in the form of molds on their lower surface, in other words, the activity of animals has an effect on They are concentrated on the upper surface and have been molded by silty sandstone and siltstone sediments after deposition. Therefore, most of the fossils were formed in the middle parts after the occurrence of turbulent currents and in a relatively calm environment.

Conclusion

Upper Cretaceous flysch deposits in Golbaf area have a good thickness and ichnofossils in this section have a very high diversity and abundance.Ethnological and sedimentology studies on the sediments of the studied area indicate calm conditions in the bed of the basin. It seems that the availability of environmental conditions such as bed oxygen, amount of organic matter in sediments, time fluctuations, textural composition of sediments, sedimentation rate, abundance of biological communities and their distribution have caused the abundance of effectors.According to the type, frequency and spread of fossils in the studied sequence, it can be concluded that a thickness of the Set bar sequence in the south of Golbaf is in suitable conditions for creating fossils.

Language:
Persian
Published:
Journal of Earth Science Researches, Volume:14 Issue: 54, 2023
Pages:
85 to 101
https://magiran.com/p2619043  
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