The contribution of condensation-corrosion in the morphological evolution of caves in semi-arid regions: preliminary investigations in the Kyrenia Range, Cyprus

The condensation-corrosion process occurs when airflow cools at the contact with colder cave walls. Condensed water becomes aggressive for soluble rocks and corrodes the walls. This process is particularly active close to cave entrances in high thermal gradient zones where external air enters caves. Condensation appears to be important where bat colonies are also present. Bat metabolism and guano decomposition release heat, vapour, and acids. Hence, bat colonies contribute to the increase of condensation- corrosion, especially by providing permanent moisture and chemical aggressiveness. Corrosive air convections produce rounded morphologies, such as ceiling channels, cupolas, and corroded older flowstones. This process has been overlooked in previous research, since related morphologies were often confused with those produced by early phreatic flow. Kyrenia Range in Cyprus has a semi-arid climate. All the studied caves developed along open-fractures. They are located both in recrystallized carbonates (limestone and dolostone, such as Smoky and Pigeons Caves), or in gypsum (First Day and Angry Bat Caves). We also studied a maze cave that acted as a spring in gypsum that initially developed under phreatic conditions, followed by an epiphreatic phase that allowed the development of notches (Fig Tree Cave, also named İncirli Show Cave). Due to the semi-arid climate, external air is very dry in summer, thus condensation seems to occur mainly in winter, when cave atmosphere instability allows large air exchanges between caves and surface atmosphere. In summer, evaporation prevails, allowing the development of popcorn lines in carbonate caves and massive gypsum crusts, stalagmites, and sidewalk rims in gypsum caves. However, the presence of a bat colony in a semi-confined chamber in Smoky Cave is probably the origin of the permanent moisture, also during the dry season, leading to a strong development of condensation-corrosion features such as ceiling cupolas, and possibly to the permanent activity of flowstones. In addition, we detected high concentrations of sulphur dioxide (SO2) and radon (Rn) in Fig Tree Cave, possibly related to the activity of the neighbouring overthrust. Based on the five studied caves in the Kyrenia Range and surroundings, the open-fracture caves in carbonates and gypsum have not undergone the typical initial phreatic stage, but have formed in a short time during Pleistocene as a result of the fast uplift of the range and were later reshaped by condensation-corrosion morphologies. Some gypsum caves may have formed entirely by this latter process, after initial minor fracture development. Cyprus is an outstanding area for studying the condensation-corrosion in caves, since a phreatic origin can be ruled out for most of the rounded morphologies. Prispevek kondenzacijske korozije pri razvoju jam v polsuhih območjih: predhodni rezultati v jamah Kirenijskega gorovja, CiperKondenzacijska korozija se pojavi ob stiku vlažnega zračnega toka s hladnimi jamskimi stenami. Pri tem na jamsko steno iz zraka kondenzira film vode, ki kemično korodira vodotopno kamnino. Proces je najbolj izrazit v bližini jamskih vhodov, kjer ob visokem temperaturnem gradientu zunanji zrak vstopa v jamo. Kondenzacijo in kondenzacijsko korozijo lahko pomembno povečajo kolonije netopirjev. Metabolizem netopirjev in razpadanje gvana sproščata toploto, vlago in kisline. Kondenzacijska korozija iz konvekcijskih tokov vlažnega zraka ustvarja zaobljene skalne oblike, kot so kupole, stropni kanali in korodirana siga. Kirenijsko gorovje na Cipru ima polsuho podnebje. Večina jam v tej raziskavi so odprte razpoke v prekristaljenem karbonatu (apnenec in dolomit) ali v sadri. Poleg teh obravnavamo tudi blodnjake v sadri, ki so se oblikovali v freatični coni in so v preteklosti delovali kot izviri. V njih najdemo stenske zajede, ki so nastale v epifreatični fazi. Ker je zrak poleti zelo suh, je kondenzacija omejena na zimski čas, ko se intenzivno izmenjuje zrak med jamsko in zunanjo atmosfero. Poleti prevladuje izhlapevanje, kar omogoča razvoj cvetačastih oblik v karbonatnih jamah ter sadrinih skorij, stalagmitov in stranskih obrob v jamah v sadri. Kolonija netopirjev v eni od polzaprtih dvoran v jami Smoky Cave verjetno vzdržuje visoko vlago tudi poleti. Posledica so močno izražene oblike kondenzacijske korozije (kupole) in stalna aktivna rast sige. V eni od jam smo izmerili visoko vsebnost SO2 in radona, ki je verjetno povezana z aktivno narivno tektoniko. Pet obravnavanih jam je tektonskega izvora in so verjetno nastale v kratkem obdobju hitrega dvigovanja v pleistocenu ter bile kasneje preoblikovane s kondenzacijsko korozijo. Nekatere jame v sadri so nastale skoraj izključno s kondenzacijsko korozijo, ki je preoblikovala prvotne majhne razpoke. Ciper je izjemno območje za podobne študije, saj lahko zaradi odsotnosti freatične faze večino zaobljenih jamskih oblik pripišemo kondenzacijski koroziji.Ključne besede: Vzhodno Sredozemlje, kondenzacijska korozija, gvano, Kirenijsko gorovje, jame v odprtih razpokah, hitri tektonski dvig, sadra, jamska mikroklima, pleistocen

Brazilian cave heritage under siege

info:eu-repo/semantics/publishe

Understanding the coupled evolution of orogens, sedimentary basins and their fluid-rock interactions

Studying orogens-basins interaction requires a multi-scale approach that combines multi-methodological field studies with basin-wide observations and integration with the dynamics of the lithosphere, the evolution of sedimentary sequences, kinematics of neighbouring mountain chains and fluid-rock interaction processes. This special issue developed out of the Sedimentary Basins Workshop (Task Force VI) of the International Lithosphere Program that took place at IFP Energies Nouvelles, France, in November 2021. It comprises 14 contributions that focus on the interactions between deep and shallow tectonic and sedimentary dynamics with fluid-flow and fluid rock interaction processes. Findings are based on field observations and associated laboratory methodologies, together with numerical modelling, that allow analysis across varied temporal and spatial scales for some of the world's best available analogues. These analogues include the orogenic systems of the Pannonian - Carpathians - Alps - Dinarides, the Pyrenees, the Mediterranean region, the Precaspian Basin and the Tibetan Plateau amongst other areas. The associated multi-scale processes that are addressed are of major societal importance, in terms of geohazards (e.g., earthquakes), geo-resources (e.g., geothermal energy, groundwater) and environmental / climatic changes (e.g., dynamic topography). Investigation of these processes in such natural laboratories and through the various applied multi-disciplinary approaches improves our understanding of the dynamic evolution of sedimentary basins and guides the future sustainable exploitation of geo-resources in the context of climate change mitigation. Throughout this special issue, fluids and their interaction with host-rocks are highlighted because most of the future usages of the subsurface will involve injecting fluids and gases underground (e.g., geothermal energy, hydrogen, or CO2 storage), and the dynamics and impacts of these applications still need to be properly understood

Advances in the understanding of multi-scale and coupled evolution of orogens, sedimentary basins and the underlying lithosphere

The integrated understanding of processes and mechanisms driving the coupled evolution of orogens and sedimentary basins and the underlying lithosphere-mantle system, requires a multi-scale temporal and spatial approach that crosses the traditional boundaries of disciplines and methodologies. While analysing the sedimentary infill we need to account for the characteristics and variations of the exhumation, evolving topography and external forcing in the source area, and the complexity of a transport system that is often characterized by a massive unidirectional sediment influx during moments of activity at tipping points or gateways. Such an influx can often span across multiple depocenters and sedimentary basins and is conditioned by an evolving structural geometry that can migrate in time, directly related to the evolving lithospheric structure in orogens that are influenced by their inherited rheology. Depocenters can be fed from multiple directions, while having an endemic or endorheic character during key evolutionary moments. The thermal structure and its variability in continental and oceanic domains conditions the rheology and subsequent structural evolution of the orogens, subduction zones and sedimentary basins, with significant consequences for understanding societally relevant issues. Quantifying basin deposition requires analysing the sediment transport network that can often span multiple interacting orogenic and sedimentary systems, where understanding the allogenic or autogenic nature of sedimentary processes can be significantly enhanced by knowing the inherited and evolving structural and tectonic parameters. Such sedimentary quantification is important for understanding the orogenic structure and the evolution of subduction systems, that include mechanisms such as cycles of burial-exhumation, formation of highly arcuate orogens and timings of nappe stacking events. Deriving processes in orogen - sedimentary basins systems also requires testing process-oriented hypotheses by focused studies in well-known natural laboratories, such as the examples from the Pannonian-Carpathians - Alps - Dinarides system and its analogues used by the numerous contributions in the special Global and Planetary Change issue entitled Understanding the multi-scale and coupled evolution of orogens, sedimentary basins and their underlying lithosphere, whose significance is explained in our review

Advances in the understanding of multi-scale and coupled evolution of orogens, sedimentary basins and the underlying lithosphere

The integrated understanding of processes and mechanisms driving the coupled evolution of orogens and sedimentary basins and the underlying lithosphere-mantle system, requires a multi-scale temporal and spatial approach that crosses the traditional boundaries of disciplines and methodologies. While analysing the sedimentary infill we need to account for the characteristics and variations of the exhumation, evolving topography and external forcing in the source area, and the complexity of a transport system that is often characterized by a massive unidirectional sediment influx during moments of activity at tipping points or gateways. Such an influx can often span across multiple depocenters and sedimentary basins and is conditioned by an evolving structural geometry that can migrate in time, directly related to the evolving lithospheric structure in orogens that are influenced by their inherited rheology. Depocenters can be fed from multiple directions, while having an endemic or endorheic character during key evolutionary moments. The thermal structure and its variability in continental and oceanic domains conditions the rheology and subsequent structural evolution of the orogens, subduction zones and sedimentary basins, with significant consequences for understanding societally relevant issues. Quantifying basin deposition requires analysing the sediment transport network that can often span multiple interacting orogenic and sedimentary systems, where understanding the allogenic or autogenic nature of sedimentary processes can be significantly enhanced by knowing the inherited and evolving structural and tectonic parameters. Such sedimentary quantification is important for understanding the orogenic structure and the evolution of subduction systems, that include mechanisms such as cycles of burial-exhumation, formation of highly arcuate orogens and timings of nappe stacking events. Deriving processes in orogen - sedimentary basins systems also requires testing process-oriented hypotheses by focused studies in well-known natural laboratories, such as the examples from the Pannonian-Carpathians - Alps - Dinarides system and its analogues used by the numerous contributions in the special Global and Planetary Change issue entitled Understanding the multi-scale and coupled evolution of orogens, sedimentary basins and their underlying lithosphere, whose significance is explained in our review