40Ar/39Ar and 18O/16O studies of the Chegem ash-flow caldera and the Eldjurta Granite: Cooling of two late Pliocene igneous bodies in the Greater Caucasus Mountains, Russia

Gazis, Carey; Lanphere, Marvin A.; Taylor, Hugh P.; Гурбанов, А. Г.

doi:10.1016/0012-821x(95)00141-x

Cited by 47 publications

(13 citation statements)

References 17 publications

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“…It is not clear whether this change has occurred gradually since the mid-Tertiary, or by abrupt reorganization(s). The Pliocene is a candidate time for a reorganization, given the onset of magmatism within the range [Gazis et al, 1995] and the increased contribution of sand from the Greater Caucasus deposited in the adjacent South Caspian Basin [Morton et al, 2003]. Therefore the Greater Caucasus is similar to the Turkish-Iranian plateau in several ways: seismicity, and presumably shortening, is focused on lower altitude areas at its margins, present convergence rates across the range Figure 7.…”

Section: Discussionmentioning

confidence: 99%

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Late Cenozoic reorganization of the Arabia‐Eurasia collision and the comparison of short‐term and long‐term deformation rates

2004

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The Arabia‐Eurasia collision deforms an area of ∼3,000,000 km2 of continental crust, making it one of the largest regions of convergent deformation on Earth. There are now estimates for the active slip rates, total convergence and timing of collision‐related deformation of regions from western Turkey to eastern Iran. This paper shows that extrapolating the present day slip rates of many active fault systems for ∼3–7 million years accounts for their total displacement. This result means that the present kinematics of the Arabia‐Eurasia collision are unlikely be the same as at its start, which was probably in the early Miocene (16–23 Ma) or earlier. In some, but not all, active fault systems, short‐term (∼10 year) and long‐term (∼5 million year) average deformation rates are consistent. There is little active thickening across the Turkish‐Iranian plateau and, possibly, the interior of the Greater Caucasus. These are two areas where present shortening rates would need more than 7 million years to account for the total crustal thickening, and where there are structural and/or stratigraphic data for pre‐late Miocene deformation. We suggest that once thick crust (up to 60 km) built up in the Turkish‐Iranian plateau and the Greater Caucasus, convergence took place more easily by crustal shortening in less elevated regions, such as the Zagros Simple Folded Zone, the South Caspian region and foothills of the Greater Caucasus, or in other ways, such as westward transport of Turkey between the North and East Anatolian faults. The time and duration of this changeover are not known for certain and are likely be diachronous, although deformation started or intensified in many of the currently active fault systems at ∼5 ± 2 Ma.

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Section: Discussionmentioning

confidence: 99%

“…Fault plane solutions show a predominance of thrusts that dip toward the range interior [Philip et al, 1989;Triep et al, 1995;Jackson et al, 2002]. Late Cenozoic magmatism in the range is Pliocene and Quaternary in age [Gazis et al, 1995].…”

Section: Greater Caucasusmentioning

confidence: 99%

Late Cenozoic reorganization of the Arabia‐Eurasia collision and the comparison of short‐term and long‐term deformation rates

2004

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“…and further East Mount Kazbek (5047 m a.s.l.). These intrusions are mainly late-collisional, subalkaline granitoids that roughly range between 4.5 and 1.5 Ma (Hess et al 1993;Gazis et al 1995;Nosova et al 2005;Lebedev & Bubnov 2006), and culminate with Quaternary volcanism reaching into the Holocene (Lebedev 2005;Chernyshev et al 2006).…”

Section: Regional Tectonics and Geodynamicsmentioning

confidence: 99%

Cenozoic-Recent tectonics and uplift in the Greater Caucasus: a perspective from Azerbaijan

et al. 2010

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The Greater Caucasus is Europe's highest mountain belt and results from the inversion of the Greater Caucasus back-arc-type basin due to the collision of Arabia and Eurasia. The orogenic processes that led to the present mountain chain started in the Early Cenozoic, accelerated during the Plio-Pleistocene, and are still active as shown from present GPS studies and earthquake distribution. The Greater Caucasus is a doubly verging fold-and-thrust belt, with a pro-and a retro wedge actively propagating into the foreland sedimentary basin of the Kura to the south and the Terek to the north, respectively. Based on tectonic geomorphology -active and abandoned thrust fronts -the mountain range can be subdivided into several zones with different uplift amounts and rates with very heterogeneous strain partitioning. The central part of the mountain range -defined by the Main Caucasus Thrust to the south and backthrusts to the north -forms a triangular-shape zone showing the highest uplift and fastest rates, and is due to thrusting over a steep tectonic ramp system at depth. The meridional orogenic in front of the Greater Caucasus in Azerbaijan lies at the foothills of the Lesser Caucasus, to the south of the Kura foreland basin.

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“…• C km −1 was calculated from borehole data within the Eldzhurtinskiy granite, in the northern part of the crystalline core of the range (Hess et al 1993;Gazis et al 1995;Grün et al 1999). An average geothermal gradient value of 40…”

Section: Thermochronometric Methodologiesmentioning

confidence: 99%

“…Hess et al (1993) and Gazis et al (1995) studied the cooling history of the small Eldzhurtinskiy granite, to the east of Elbrus (Fig. 2), primarily using 40 Ar-39 Ar biotite cooling ages from borehole samples.…”

Section: Previous Workmentioning

confidence: 99%

The exhumation of the western Greater Caucasus: a thermochronometric study

Vincent

Carter

Lavrishchev³

et al. 2010

Geol. Mag.

124

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-This study provides 39 new thermochronometric analyses from the western part of the Greater Caucasus, a region in which existing data are extremely limited and of questionable quality. The new results are consistent with field studies that identify Triassic to Middle Jurassic (Cimmerian) and Oligo-Miocene (Alpine) orogenic erosional events. An inverse relationship between the fission track and depositional ages of Oligo-Miocene sedimentary samples also implies some degree of Eocene erosion of the Greater Caucasus and intermediate sediment storage. Cooling ages and field relationships within the core of the range, west of Mt Elbrus, require ∼ 5 km of Permo-Triassic exhumation and restrict the overall amount of Cenozoic exhumation to ∼ 2.5 km. Current exhumation rates are typically low, and do not support a Plio-Pleistocene increase in climate-driven denudation. High (∼ 1 km Ma −1 ) rates of exhumation are restricted to the southern flank of the range in northwest Georgia. Despite a general lack of significant seismicity within the study region, this exhumation peak is close to the largest instrumentally recorded earthquake in the Caucasus (Ms = 7.0). This may suggest that exhumation is associated with the decoupling of the sedimentary succession from its crystalline basement in the southern part of the range and the inversion of the largely Jurassic fill of the Greater Caucasus basin. Rates of exhumation are compatible with this being driven by active shortening. Further sampling and analysis are required to provide a higher-resolution, low-temperature thermochronology of Alpine exhumation, to isolate the drivers for Palaeogene Dziruli Massif cooling and uplift, and to constrain better the extent of the current, localized phase of rapid exhumation.

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40Ar/39Ar and 18O/16O studies of the Chegem ash-flow caldera and the Eldjurta Granite: Cooling of two late Pliocene igneous bodies in the Greater Caucasus Mountains, Russia

Cited by 47 publications

References 17 publications

Late Cenozoic reorganization of the Arabia‐Eurasia collision and the comparison of short‐term and long‐term deformation rates

Late Cenozoic reorganization of the Arabia‐Eurasia collision and the comparison of short‐term and long‐term deformation rates

Cenozoic-Recent tectonics and uplift in the Greater Caucasus: a perspective from Azerbaijan

The exhumation of the western Greater Caucasus: a thermochronometric study

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