ON THE TYPES OF TRAPS FORMED IN THE KUR AND SOUTH CASPIAN DEPRESSIONS AND THE ROLE OF TECTONIC FAULTS IN THEM

Abstract

The relevance of the study is caused by the fact that in Azerbaijan, as well as around of the world, oil and gas deposits associated with anticlinal types of traps are rapidly exhausted. Just this situation makes the issue relevant and requires studying the diverse, mainly non-anticlinal and combined traps and their prospects (where tectonic disturbances are of considerable importance). The carried out research can provide reliable information on the study of traps in both the Kura and South Caspian basins, which were developed in absolutely different geological and tectonic conditions. The aim of the research is to determine the nature of tectonic evolution of the Kura and South Caspian basins areas and analyze the structure of heterogeneous traps formed in them. Methods. Using a computer software the author has built a territory model and reconstructed paleotectonic conditions that clearly illustrate evolution and location of both depressions. As a result of modeling and research of the paleotectonic evolution of the region, it was revealed that if traps are characterized by the anticlinal type in the sandy horizons of the productive series within South Caspian depression, in the Kura depression they belong to non-anticlinal ones and are mainly associated with Paleogene-Miocene, Eocene and Upper Cretaceous age's layers. Results. Anticlinal type traps are formed mainly as a result of horizontal tectonic stresses, but non-anticlinal traps are fully formed in conditions, reflecting various stages of the evolution of the earth's crust. Only tectonic movements play a significant role in occurrence of various forms of geological entities and geometric units in which various types of traps are formed, which morphologically differ from each other, depending on the influence of the main factor and the formation conditions. The studies have revealed that tectonically shielded deposits are mainly associated with the South Caspian depression, while the Kura depression is more appropriate for the formation of predominantly massive deposits associated with erosion protrusions of the basement and effusive «cores». Studying these issues allows predicting the prospect of finding complex traps in view of geometric detail and shape. The study of the conditions for formation of heterogeneous traps makes it possible to determine both their lithological composition and distribution ranges. In particular, it was determined that the spatial position of Kura depression structures to a certain extent differs from the structures of the South Caspian depression in terms of spatial location. In other words, it is not particularly possible to find a specific arrangement of structures in the Kura depression, while the folds within South Caspian depression clearly reflect the results of compressive stresses and their predominant role in the orientation of uplifts. Within the considered territory, the anticlinal, non-anticlinal, and combined type traps are mainly observed in deep lying deposits and they are of especial interest from the point of view of prospecting for oil and gas reserves. It should be taken inro account that, as a result of tectonic and other repeated effects, the formed traps have a more complex shape.

Keywords

• anticlinal
• nonanticlinal
• reservoir
• hydrocarbons
• movements
• screen
• process
• wedging
• trap
• oil
• gas
• deposit