Sedimentology of coexisting travertine and tufa deposits in a mounded geothermal spring carbonate system, Obruktepe, Turkey

Abstract

The recent discoveries of deeply buried Cretaceous reservoir bodies in the Atlantic Ocean revealed that relationships between the distribution of spring carbonate deposits and faults are poorly understood. The well‐exposed Quaternary deposits at Obruktepe (Denizli Basin, Turkey) provide an opportunity to reconstruct the three‐dimensional sedimentary architecture of such a system. Integration of sedimentological, lithofacies and geochemical analyses reveals complexity in the lateral relationships between sedimentary environments, faults and geothermal spring carbonates. Five environmental systems are distinguished based on the lithofacies analysis: (i) vent; (ii) smooth slope; (iii) travertine‐terrace; (iv) tufa‐barrage; and (v) flood systems. Encrusting, baffling and settling sedimentary processes are reflected in data acquired at several scales, from lithofacies observations to the morphology and arrangement of geobodies, together with microfabrics and stable carbon and oxygen isotope data. Mean values of +4·9‰ δ13C and −8·74‰ δ18O Vienna PeeDee Belemnite reflect geothermal circulation of springwaters. The environmental distribution and lithofacies indicate a lateral continuum between travertine and tufa deposits within this hot spring system. This finding supports two depositional models in which water flow variation is the main control on both CaCO3 precipitation and the resulting formation of travertine and tufa. The proposed models address the factors responsible for the development of these complex mound‐shaped carbonate spring deposits, and how they are related to fluid circulation at depth and in association with faults.

Syn‐sedimentary hydrothermal dolomites in a lacustrine rift basin: Petrographic and geochemical evidence from the lower Cretaceous Erlian Basin, Northern China

“…2) suggests rapid decay in precipitation potential with distance from the source of hydrothermal fluids (e.g. Dekov et al, 2014;Lopez et al, 2017). Firstly, the onset of hydrothermal activity was marked by formation of laminae or bands of Md dolomites intercalated with unconsolidated lacustrine sediments layers, giving way up-section to deposition of intermixed muds/silts and Md dolomites.…”

What do we really know about early diagenesis of non-marine carbonates?

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Searching for biosignatures in sedimentary rocks from early Earth and Mars

“…These facies also record microbial growth in the zones characterized by different physical and chemical conditions determined by degassing, the influx of cation-rich groundwater and evaporative concentration of ions in the splash zones. Microbial growth in the presence of standing bodies of water creates additional recognizable facies, including mounds, pools, terracettes, palmate tufa towers, streamers, cascading overhangs, rafts, encrusted pebbles, small and large columnar thrombolites and stromatolites, coated bubbles, shrubs, ooids, pisoids, spherulites and other structures [160][161][162][163][164][165][166][167][168][169][170][171][172][173][174][175][176] .…”

“…In Lake Salda, diatoms and cyanobacteria appear to be the principal builders of cm-thick gelatinous coatings that cover stromatolites, ultramafic rocks or wood and contain microcrystalline platy hydromagnesite 166,228 . The association of microcrystalline and nanocrystalline hydromagnesite with alveolar EPS and sheaths of filamentous cyanobacteria indicate that the activities of organisms and processes that produce and degrade EPS strongly control the precipitation of this mineral 169,182,[228][229][230] . The exposed stromatolites and stromatolites that lack microbial coatings in Lake Salda, as well as the exposed microbial mats in playa lakes, are porous, friable and thought to be susceptible to erosion 166,225,231 .…”