Fluid seepages at the eastern Greater Caucasus and Talysh mountains (Azerbaijan): Fluid geochemistry, structural and geodynamic controls

Project leaders

Marco Bonini, Akper Feyzullayev

Agreement

AZERBAIJAN - ANAS - Azerbaijan National Academy of Sciences

Call

CNR/ANAS 2014-2015

Department

Earth system science and environmental technologies

Thematic area

Earth system science and environmental technologies

Status of the project

Extended

Report for renewal

relaz-accordo-cnr-anas00350420130917123554.pdf

Research proposal

The present project proposal follows the 2012-2013 bilateral project between ANAS (Azerbaijan) and CNR (Italy). The 2012-2013 project has addressed all the planned objectives (see the attached Joint Report 2012-2013), yet the researches have disclosed a number of issues that motivate the renewal request for 2014-2015. In particular, we intend to focus on, and to extend our investigations to other sectors of Azerbaijan, which represents a natural laboratory showing obvious connections between the chemical and isotopic features of different types of fluid discharges and the ongoing tectonic movements. In order to achieve solid constrains of mud volcano and tectonic deformation rates, we have put the basis for undertaking a DInSAR analysis of satellite images, which integrates fully with the fluid geochemistry and geological-structural studies that represent the core disciplines of the 2012-2013 project. This task has been achieved through the opening of a 3-year PhD position (started in November 2012), and the application to the European Space Agency per for the provision of the necessary satellite images (the project has been approved in spring 2013).
In the new 2014-2015 proposal, we aim to achieve a more comprehensive framework of the relationships between the release of deep-sourced fluids and active deformation in eastern Caucasus-South Caspian region. The Greater Caucasus extents for more than 1000 km in a ENE direction forming the northernmost margin of the deformation zone produced by the collision of Arabia with Eurasia. Southward, the Kura Basin separates the Greater Caucasus from the Lesser Caucasus and Talysh ranges. Recent GPS surveys reveal shortening rates of 10 to 13 mm/yr across the easternmost Caucasus, particularly the velocities deduced from GPS stations within the Kura Basin and Lesser Caucasus-Talysh increase eastward and move toward N20°E relative to Eurasia (Reilinger et al., 2006). The observation that the Lesser Caucasus-Talysh move northward ~7 mm/a faster than the Greater Caucasus suggests that active shortening is accommodated at the Kura fold-and-thrust belt, which flanks the southwestern margin of the Greater Caucasus (Forte et al., 2010). Our research proposal is thus centered on the easternmost part of Greater Caucasus and Talysh mountains, a region which GPS, seismic and geological data indicate to have focused much of the shortening. There is however limited seismicity within the Kura fold-thrust belt, most likely because deformation is essentially aseismic being this belt detached along the overpressured Maykop shales (Jackson et al., 2002).
The Kura fold-and-thrust belt comprises trains of south-to-southwest vergent fold anticlines that affect the Pliocene-Pleistocene sediments. Several lines of structural and geomorphic evidence suggest that these fold anticlines are actively growing (Forte et al., 2010). The easternmost part of the Kura fold-and-thrust widens toward the South Caspian Sea, where mud volcanoes are widespread and typically puncture the crest of the anticlines (Jakubov et al., 1971). The easternmost part of the Kura fold-thrust belt has been however overlooked in the previous geomorphologic-structural studies, and thus the present proposal aims to fill this gap by extending these analyses to this sector. The preliminary results are promising. In particular, morphological analysis combined with the interpretation of available seismic lines suggest that some anticlines have exerted a control on the hydrographic pattern of the Kura River. Current available data are however insufficient to confidently determine the deformation rates and how these operate over short term periods (years). In this regard, the DInSAR analysis of satellite images will be crucial to assess the amount of the ongoing vertical movements. To achieve a quantitative estimation of the long term vertical movements, we have performed a sampling for apatite fission-track (AFT) thermochronology of the Pliocene strata folded at the frontal part of the Kura fold-and-thrust belt. The first samples have been treated and soon will be sent out for irradiation.
Mud volcanism is thus apparently linked to the fastest deformation rates determined in eastern Kura, in addition to the prerequisite of subsurface accumulation of hydrocarbon gases (Feyzullayev and Lerche, 2009). Similarly to magmatic volcanoes, gases play an important role in the ascent and extrusion of the subsurface material (essentially mud breccias). The published results carried out in the frame of the 2012-2013 project indicate that the thermogenic gases emitted from the mud volcanoes originate at relatively high pressure and temperature up to 120-150°C (Bonini et al., 2013). New fluid and gas samples have been collected in June 2013 along a transect extending through the Kura and Greater Caucasus belts, with the purpose to assess the relationships between tectonic structures and fluid seepage over a wider portion of Caucasus. These samples are currently the object of numerous isotopic determinations. The initial results are encouraging, even though a further on-site mission would be necessary to finalize the sampling.
As mentioned above, the structural and geochemical researchers will be extended to the Azerbaijan territory of the Talysh mountains. The latter takes up part of the regional Arabia-Eurasia convergence especially along the eastern side of the range, where it accommodates the deformation induced by the motion of the adjacent, rigid, South Caspian basement block (Jackson et al., 2002; Allen et al., 2003). The structural pattern of Talysh consists of arcuate, convex-northwards, E-W to N-S-trending thrust faults merging with ~N/NNE-trending right-lateral faults (i.e., the Sangavar Fault), consistent with the northward movement of the Talysh range with respect to the South Caspian block (Allen et al., 2003). The occurrence in the Talysh mountains of dry and aqueous seeps showing markedly different main components (CO2, N2, and CH4) (Feyzullayev and Abbasova, 2008) is intriguing, and may reflect the above mentioned structural complexity, in terms of different depths of the sources exploited by the tectonic-controlled pathways. Accordingly, the emitted fluids will be sampled and analyzed to establish the geochemistry and isotopic values, particularly helium, argon, light hydrocarbons (C1-C10 compounds), CO2, H2S and N2 to get insights into the potential fluid sources (mantle, crust?) and thereby the depth origin of gases. The DInSAR analysis will investigate the occurrence, rates, and characteristics of ongoing tectonic movements. Both the structural and DInSAR analyses will be coupled with a thermochronologic study that will explore the exhumation history of Talysh over the last million years.
Results from this research are expected to improve our understanding of (i) continental collision, (ii) the geological conditions that allow the emission of deep-sourced fluids, including those leading to the paroxysmal activity of mud volcanoes, and (iii) the seismic hazards in this economically important country. This region has been indeed struck by strong earthquakes, such as the seismic sequence (Mw 6.2) that hit offshore Baku in 2001. Dynamic stresses produced by seismic events have long been shown to have occasionally triggered large eruptions at mud volcanoes. In this regard, the DInSAR analysis will also focus on the potential ground deformations preceding a mud volcano eruption. This effort may have relevance because the mud volcanoes may experience strong flaming or effusive eruptions that have the ability to seriously damage roads, buildings, and may even represent a risk for human safety, especially when the mud volcanoes occur in very populated areas.
REFERENCES
Allen, M.B., Vincent, S.J., Alsop, G.I., Ismail-zadeh, A., Flecker, R., 2003. Late Cenozoic deformation in the South Caspian region: effects of a rigid basement block within a collision zone. Tectonophysics 366, 223-239.
Bonini, M., Tassi, F., Feyzullayev, A.A., Aliyev, C.S., Capecchiacci, F., Minissale, A., 2013. Deep gases discharged from mud volcanoes of Azerbaijan: New geochemical evidence. Mar. Pet. Geol. 43, 450-463.
Jackson, J., Priestley, K., Allen, M., Berberian, M., 2002. Active tectonics of the South Caspian Basin. Geophys. J. Int. 148, 214-245.
Jakubov, A., A. Ali-Zade, Zeinalov M., 1971. Mud Volcanoes of the Azerbaijan, SSR, Publ. House of the Acad. of Sci. of the Azerbaijan SSR, Baku. 256 pp.
Feyzullayev, A.A. and Lerche, I., 2009. Occurrence and nature of overpressure in the sedimentary section of the South Caspian Basin, Azerbaijan. Energy Exploration & Exploitation 27, 345-366.
Feyzullayev A.A., Abbasova S.V. 2008. Nature of gases of mineral springs in Talysh based on isotope composition of helium and argon. Geophysical news in Azerbaijan, 3-4, 55-57.
Forte, A.M., Cowgill, E., Bernardin, T., Kreylos, O., Hamann, B., 2010. Late Cenozoic deformation of the Kura fold-thrust belt, southern Greater Caucasus. GSA Bulletin 122, 465-486.
Reilinger, R., et al., 2006. GPS constraints on continental deformation in the Africa-Arabia-Eurasia continental collision zone and implications for the dynamics of plate interactions. J. Geophys. Res. 111, B05411.

Research goals

We aim to achieve a more comprehensive framework of the active deformation patterns and fluid-fault interactions over a sector encompassing the eastern Kura fold-thrust belt and the Talysh mountains in Azerbaijan. These aspects will be investigated through a field-based, structural, geochemical, and thermochronologic study, integrated with DInSAR analysis of satellite images. The results of this research will advance our knowledge of a variety of processes operating in regions characterized by continental collision, particularly:
1. The interplay between various types of active tectonic structures and the ascent of deep-sourced fluids. The consideration of the eastern Caucasus and Talysh is expected to be particularly fruitful because these regions expose different types of tectonics structures and the seeps show markedly differences in fluid geochemistry.
2. The quantitative estimation of vertical exhumation rates of ranges actively growing within a deformation zone produced by continental shortening. The short-term rates will be analyzed through a DInSAR analysis, which will focus on the eastern Kura fold-thrust belt and Talysh. Apatite fission-track thermochronology will instead address the long-term exhumation rates of the same regions.
3. Finally, results may be also relevant for economical aspects related to petroleum prospectivity of Azerbaijan, as well as for those concerning the seismic hazard in the region. Besides damaging infrastructures, seismic events may heavily impact on mud volcano activity, and thus the research will also focus on the response of these features to the stress changes caused by earthquakes.

Last update: 27/11/2021