Stratigraphy and Palaeontology
Zeinab Manouchehri; Tayebeh Mohtat; Seyed Ali Aghanabati; Morteza Khalatbari Jafari; Fatemeh Vakil Baghmisheh
Abstract
The sediments are generally limestone and marl. The lower boundary with the loer red Formation is disconfomity and the upper boundary with the equivalent formatin of Bakhtiari Firmation is paraconformity. The total number of fossils found in this section is 69 species, 72 genera and 46 families. These ...
Read More
The sediments are generally limestone and marl. The lower boundary with the loer red Formation is disconfomity and the upper boundary with the equivalent formatin of Bakhtiari Firmation is paraconformity. The total number of fossils found in this section is 69 species, 72 genera and 46 families. These sediments are formed in an open shelf and under the open sea and lagon environment. The variety and abundance of bentic foraminifer’s forms and the low presence of plagic forms testify to the shallow basin in this section, which is also confirmed by the study of other fossils. One of the Markable features of this section is the presence of Ammonia species, especially Ammonia parkinsonia. This section has a complete sequence of members of Qom Formation. This species are profe of shallow water and continental shelf for this carbonates. This section consist all of members of Qom Formation and based on identified foraminifera comparable to assemblage zone 1 & 2 introduced by Adams & Bourgeois (1967). These zones that inclod: 1-Borealis Melo Group- Meandropsin; 2- Miogypsinoides- Archaias- Valvulinid. Based on index foraminifer's species and their stratigraphic distribution the age of this section is Chatian- Burdigalian (Upper Oligocene-Lower Miocene)
Petrology
Morteza Khalatbari Jafari; Narmin Banehee; Mohamad Faridi; Mehdi Moradi
Abstract
The Neogene volcanic rocks are exposed in south Arab abad, Lut block. The studied volcanic rocks covered Eocene and Oligocene volcanic lavas and Neogene evaporitic deposits. The base of the Neogene volcanic sequence made of breccia and tuff gradually covered by andesite, trachyandesite and dacitic lavas. ...
Read More
The Neogene volcanic rocks are exposed in south Arab abad, Lut block. The studied volcanic rocks covered Eocene and Oligocene volcanic lavas and Neogene evaporitic deposits. The base of the Neogene volcanic sequence made of breccia and tuff gradually covered by andesite, trachyandesite and dacitic lavas. These lavas have aphyric-phyric textures and microlitic to hyalomicrolitice in matrix. These lavas show calck alkaline magmatic trend. REE patterns and spider diagrams display enrichement in LREE and LILE relative to HREE and depletion in HFSE which like as subduction zone magmatism. In the tectonomagmatic diagrams they plot of subduction and post-collisions fields. Interpretation of the geochemical data indicates that the studied lavas probably produced from partial melting of lithospheric mantle which had previously enriched by subduction components (fluids and melt). Partial melting of crust, probably involved in generation of acidic lavas. It seems that in the Neogene period, lithosphere thinning induced partial melting of heterogeneous Sub Continental Lithospheric Mantle (SCLM). These processes consequently occurred by lithospheric delamination and asthenospheric upwelling.
