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

Abstract

A travertine fissure ridge and travertine mound are situated ~800m from each other at the western margin of the active tectono-volcanic Sanandaj-Sirjan zone (western Iran). Despite their close proximity, the two geobodies show a difference in morphology, lithofacies, lithotypes, diagenesis and geochemistry. Petrographic analysis of the fissure ridge carbonates revealed homogeneous sparitic fabrics with dendritic structures reflecting precipitation under fast-flowing conditions from calcite supersaturated spring water. The mound carbonates are much more heterogeneous and display dominantly micritic fabrics with (mainly volcanic) clasts reflecting a lower energy flow regime and lower calcite saturation. In contrast to the limited diagenetic overprint of the fissure ridge carbonates, the more porous mound carbonates are affected by dissolution, cementation, and formation of Mn/Feoxide/hydroxides, attesting of a strong control on porosity by early diagenetic processes. The widespread bright luminescent calcite phases especially in sparitic fabrics within both geobodies display high Mn concentrations in calcite indicating suboxic precipitation conditions. 2The overlapping 87 Sr/ 86 Sr signatures and δ 13 C signatures point to a mixture of CO2 that dominantly originated from dissolution of the marine carbonate Qom Formation (Oligo-Miocene). The different δ 18 O signatures, indicate different upwelling systems caused by different substrate settings. The fissure ridge formed on a hard and brittle limestone substrate with precipitation from dominantly subsurfacesourced fluids. The mound travertine formed on top of fairly unconsolidated and fractured volcanic strata. The depleted δ 18 O signatures and impure micrite-dominated fabrics of the mound travertine reflect precipitation from thermal water that mixed with surrounding groundwater. This difference is also reflected in a different calculated precipitation temperature, that varies between 4-21°C for the mound versus 25-50°C for the fissure ridge.Our findings show that subsurface geology exerts a major control on precipitation processes resulting in differences in travertine morphology, sedimentology, diagenesis, and geochemistry, despite that the travertine bodies occur adjacent to each other.

Factors controlling the geometry of travertine mounds: Insights from Heinitang (China)

“…Comparison of the stable carbon‐oxygen isotope composition of typical travertine mounds. Original data: Rongma (Qin et al ., 2014), Shiqiang (Jones & Peng, 2017), Stjáni (Pentecost, 2011), Grab (Goleij et al ., 2018), Babagorgor (Mohammadi et al ., 2019), Bullicame (Della Porta et al ., 2021), Rabbitkettle Hot Springs (Gulley, 1993), Porcelana Geysers (Ruiz Velásquez, 2019). δ 13 C of travertine and tufa is from Pentecost & Viles (1994).…”

Fissure Ridges: A Reappraisal of Faulting and Travertine Deposition (Travitonics)

“…Several fissure ridges have been described around the world by many authors, developed from the Mesozoic period [17,18] to the present [9,10,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Furthermore, the recent exploration of planets of the Solar System has also highlighted the possible existences of fissure-ridge-type travertine deposits and associated mounds in extra-terrestrial settings, as was "described" for Mars [38][39][40][41].…”

High geogenic arsenic concentrations in travertines and their spring waters: Assessment of the leachability and estimation of ecological and health risks

“…Quaternary Babagorgor travertines are characterized by two dominant morphologies, namely spring mounds and fissure ridges. Both inactive and active spring mounds are characterized by micritic fabrics, while the fissure ridges are dominantly composed of sparitic fabrics (Mohammadi et al, 2019). Although both morphologies have been considered in this study, the main focus is on the mound travertines which contain the highest concentrations of As.…”

“…Detailed petrographic and sedimentological analyses based on the macroscopic description (bed geometry, texture, sedimentary features, and faunal content) and characteristics of accessory grains and matrix composition have been reported in Mohammadi et al (2019). An overview of the different samples and associated mineralogy is given in Table 3.…”

“…In this study, two travertine deposits that occur contiguously, but display different morphology and textural framework, as well as geochemical signatures, were selected for a thorough petrographical (Mohammadi et al, 2019) and geochemical study. The first travertine type dominantly possesses a sparitic fabric consisting of almost pure calcite and a low content of non-carbonate components; while the second travertine body displays a dominant micritic fabric consisting of fine-crystalline calcite with a relatively high non-carbonate content, mainly consisting of clay minerals.…”