Stable isotope geochemistry and petrography of the Qorveh–Takab travertines in northwest Iran

Abstract

The Qorveh-Takab travertines, which are connected to thermal springs, are situated in the northwest of the Sanandaj- Sirjan metamorphic zone in Iran. In this study, the travertines were investigated applying petrography, mineralogy and isotope geochemistry. Oxygen and carbon isotope geochemistry, petrography, scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) analysis were used to determine the source of the CO2 and the lithofacies and to classify the travertines. Isotope studies, morphological and mineralogical observations and distribution of travertines revealed that the travertines of the Qorveh-Takab could be of thermal water origin and, therefore, belong to the thermogene travertine category. These travertines are usually massive with mound-type morphology and are essentially found in regions with recent volcanic or high tectonic activity. The measured δ13C values of the travertines indicate that the δ13C of the CO2 released from the water during travertine deposition, while the source of the CO2 in the water springs seems to have been of crustal magmatic affinity. These travertines are divided into two lithofacies: (1) crystalline crust travertine and (2) pebbly (phytoclastic travertine with pebble- size extraclasts) travertine. δ18O and δ13C values of travertines are -0.6 to -11.9 (‰VPDB) and +6.08 to +9.84 (‰VPDB), respectively. A probable reason for the heavy carbon isotope content observed in these deposits is the presence of algae microorganisms, which was verified by SEM images. Fissure ridges, fluvial crusts with oncoids, and mound morphological features are observed in the study area. Based on the petrographic and SEM criteria, Qorveh-Takab travertines are classified into four groups: (1) compacted, (2) laminated, (3) iron-rich spring deposit and (4) aragonite-bearing travertines. Stable isotope compositions of Turkish travertines are largely similar to the travertines in the study area.

Low‐Temperature Thermochronologic Response to Magmatic Reheating: Insights From the Takab Metallogenic District of NW Iran, (Arabia‐Eurasia Collision Zone)

“…These volcanics locally overlain the URF (Mehrabi et al, 1999) or intrude it as documented by an ∼11-Myr-old dacitic dome (Figure 2, Heidari, 2013). Finally, polygenic conglomerates of supposed Plio-Pleistocene age, were deposited along the margins of the TRC (Babakhani & Ghalamghash, 1998), while Quaternary travertines developed in the western sectors of the study in association with ongoing hydrothermal activity (Figure 2, Roshanak et al, 2018).…”

Substrate geology controlling different morphology, sedimentology, diagenesis and geochemistry of adjacent travertine bodies: A case study from the Sanandaj-Sirjan zone (western Iran)

“…These morphologically different travertines can be important archives with regard to the controlling parameters that gave rise to these geobodies. Despite that some studies provided important insights into the nature and types of volcanism in the study area (Sepahi and Athari, 2006;Azizi and Jahangiri, 2008;Azizi and Moinevaziri, 2009;Razavi and Sayyareh, 2010;Azizi et al, 2013), structural geology (Mohajjel et al, 2003;Ghasemi and Talbot, 2006) and some overall knowledge on the petrography and stable isotope geochemistry of the HTV travertines recently became available (Roshanak et al, 2018), very little information about the interplay between geological setting, sedimentology, diagenesis and geochemistry is known about these travertine deposits. Consequently, this study provides a detailed characterization of the mound and fissure ridge carbonates including variation and contrast in geobody architecture, fabrics, diagenesis and geochemistry in order to address the controlling factors.…”