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

Andrea Brogi,Lianchao Luo,Mehmet Cihat Alcicek,Enrico Capezzuoli,Volkan Karabacak

doi:10.3390/geosciences11070278

Abstract

The mechanical discontinuities in the upper crust (i.e., faults and related fractures) lead to the uprising of geothermal fluids to the Earth’s surface. If fluids are enriched in Ca2+ and HCO3-, masses of CaCO3 (i.e., travertine deposits) can form mainly due to the CO2 leakage from the thermal waters. Among other things, fissure-ridge-type deposits are peculiar travertine bodies made of bedded carbonate that gently to steeply dip away from the apical part where a central fissure is located, corresponding to the fracture trace intersecting the substratum; these morpho-tectonic features are the most useful deposits for tectonic and paleoseismological investigation, as their development is contemporaneous with the activity of faults leading to the enhancement of permeability that serves to guarantee the circulation of fluids and their emergence. Therefore, the fissure ridge architecture sheds light on the interplay among fault activity, travertine deposition, and ridge evolution, providing key geo-chronologic constraints due to the fact that travertine can be dated by different radiometric methods. In recent years, studies dealing with travertine fissure ridges have been considerably improved to provide a large amount of information. In this paper, we report the state of the art of knowledge on this topic refining the literature data as well as adding original data, mainly focusing on the fissure ridge morphology, internal architecture, depositional facies, growth mechanisms, tectonic setting in which the fissure ridges develop, and advantages of using the fissure ridges for neotectonic and seismotectonic studies.

Highlights

In geothermal areas with carbonate reservoirs, thermal springs and travertine deposition have inseparably combined the effects of brittle deformation at shallow crustal levels ([1,2], and references therein])
Here below we describe the state of the art and updated knowledge on the fissure ridges, summarizing a large amount of information recently published on different fissure
We aim to emphasize how these results update the potentiality of the fissure-ridge-type travertine deposits for neotectonics and seismotectonic investigations

Summary

Introduction

In geothermal areas with carbonate reservoirs, thermal springs and travertine deposition have inseparably combined the effects of brittle deformation at shallow crustal levels ([1,2], and references therein]). The internal part of the fissure is often cut by a network of sealed fractures, almost parallel to the long axis of the ridge, normally filled by banded Ca-carbonate (i.e., calcite and/or aragonite), almost parallel to the vein-walls (the so called “banded travertine” in [9,10]). These veins developed within the fault zone and represent conduits along which geothermal fluids move towards the surface [12,13]. We aim to emphasize how these results update the potentiality of the fissure-ridge-type travertine deposits for neotectonics and seismotectonic investigations

Fissure Ridge Morphology and Internal Architecture

Facies

Growth Mechanisms

Tectonic Settings Favoring Fissure Ridge Development

Advantages of Using Fissure Ridges for Neotectonic and Seismotectonic Studies