Mesozoic Limestones Research Articles

The effect of lunar declination on CO<sub>2 </sub>degassing from central Italian Apennines

<p>The periodical degassing from CO<sub>2</sub> over-pressured reservoirs may have serious consequences for the environment making urgent understanding the processes and forecasting the frequency. Prediction though needs methods that depends from temporal and spatial properties of hydro-chemical and physical reservoir characteristics that unfortunately are often lacking. We have analyzed surface emissions of CO<sub>2</sub> attributed to over-pressured CO<sub>2</sub>-rich reservoirs in the Central Italian Apennines a zone characterized by significant periodical CO<sub>2</sub> degassing. Here aquifers are hosted in Mesozoic limestone with high pCO<sub>2</sub> groundwater and travertine deposits. We analyzed a 10-year temporal series and found that in the Apennines CO<sub>2</sub> flux and aquifer fluid composition are correlated with the lunar tides. In particular, our study reveals that low CO<sub>2</sub> flux corresponds with low lunar tidal potential values. We found a similar trend for dissolved calcium and water alkalinity, while pH values display a linear correlation with tidal cycles. The forces associated with tidal potentials are not capable of fracturing rock. However, they can, under certain conditions, drive the flow of fluids in over-pressured reservoirs, triggering sub-surface fluid movements that in turn modify the water�Crock reactivity. In the central Apennines, we show that these movements result in increased dolomite dissolution and an eventual return to calcite equilibrium. In this case, dolomite dissolution breaks the rock releasing calcium into ground water, which leads to calcite equilibrium and in turn to the formation of significant quantities of travertine and the concomitant release of CO<sub>2</sub> in the atmosphere.</p>

A geological overview of the limestone members of the Woyla Group of Sumatra, Indonesia

Mesozoic limestone units of the Woyla group were identified in many places across the northern part of Sumatra, Indonesia. Even though these sedimentary rocks may play an important role as an element of the potential Pre-Tertiary hydrocarbon play of Sumatra, their characteristics are still not well understood. This study tries to fill this research gap and aims to better understand the characteristics of the limestone members of the Woyla group. There are three objectives of this study: (1) to characterise structural features, and deformation of the Woyla Group; (2) to provide sedimentary characteristics of the limestone members of the Woyla Group; and (3) to understand the main influences on the development of the limestone members of the Woyla Group. An integrated geological analyses, including structural scanline analysis, petrographic analysis, and acid digestion analysis, was conducted to achieve the objectives of this study.
 Findings from this research show that the limestone members of the Woyla group were strongly deformed, and structural features such as bedded strata, faults, folds, and joints were identified within these rocks. The limestone units of the Woyla group consist of at least six microfacies. These are wackestone, packstone, wackestone-packstone, packstone-rudstone, fossiliferous sandstone, and fossiliferous shale. Depositional processes, sea level fluctuations, tectonisms, and climatic variations are interpreted as the main factors influencing the development and evolution of these limestone units. It is expected that the results of this study could advance our understanding of the Pre-Tertiary carbonate rocks in general, and the Woyla group of Sumatra in particular.

Petrographic and Geochemical Inferences for Genesis of Terra Rossa: A Case Study from the Apulian Karst (Southern Italy)

Terra rossa is a reddish clay soil which is often present on the surface of limestone in regions with a Mediterranean-type climate. Its genesis is a controversial subject in terms of the origin of the parent material, from the residuum of underlying (carbonate/dolomite) bedrock in the absence/presence of an external silicate contribution (e.g., aeolian dust). Within this context the main goal of the present work was the understanding of the geochemical processes leading to the formation of the terra rossa starting from the carbonate bedrock. We report the results of a multi-method analysis on a terra rossa deposit occupying the bottom of a Quaternary karst depression on Mesozoic limestones exposed in the Murge area (Apulia Foreland, southern Italy). Geological, petrographic, textural, and chemical data were collected on karst products (reddish calcite incrustations and nodules, and fine-grained portion of terra rossa) by a detailed field mapping, optical microscopy, XRF and fusion ICP/MS analyses and by scanning electron microscope. New collected data show that the mineralogical composition of reddish incrustations and nodules is comparable, consisting of fibrous and impure calcite, detrital fragments of quartz, K-feldspar, zircon and authigenic minerals as (Mn, Ba, Ca) phases, (Al, Si, Mn, Fe, Mg, Ba, Ca) minerals, Fe-kaolinite and anatase. The prevailing minerals, instead, in the fine-grained portion of terra rossa are hematite, kaolinite, and goethite. Based on the chemical composition, and especially on REE patterns, a progressive interaction of silicate aqueous solutions (with Al, Si, Fe), containing pelite material, with the calcareous bedrock, as a source of carbonic acid, was the process driving the formation of terra rossa. Obtained results add new elements to the definition of the long-lasting question about the genetic processes responsible for the formation of terra rossa, corroborating their polygenetic origin, as result of limestone alteration in conjunction with the chemical interaction with allochthonous siliciclastic material.

Via Transilvanica in the Mehedinți County

"Via Transilvanica is a cultural pedestrian road that connects three historical regions of Romania: Moldova, Transylvania and Banat. Kilometer zero of this road is in the municipality of Drobeta Turnu Severin, where the history of the Romanian people began, consisting of the symbiosis of Dacians and Romanians. The road, initiated and built during last 4 years, by the Ușeriu brothers, is marked, from kilometer to kilometer, with andesite markers that were carved by volunteer artists with symbols representing the main tourist attractions on each route. The Via Transilvanica includes 7 segments, depending on the historical areas: Bucovina, Tinutul de Sus, Terra Siculorum, Terra Saxonum, Terra Dacica, Terra Banatica and Terra Romana. Travelers have to follow a number of 67 routes walking or cycling. In the Mehedinți county, this road includes 5 of the 7 routes of Terra Romana. Tourists cross the Mehedinți Plateau towards the Mehedinți Mountains, passing through one of the main karst areas in Romania, across the Mesozoic limestone bar Cireșu-Baia De Aramă. The Via Transilvanica project aims to culturalize the masses and to develop the local economy in particular. In the Mehedinți county, one of the risks is related to protected natural areas and carrying capacity."

A Tainted Place in Central Anatolia: Kırkdilim Road (Çorum-Turkey)

Building roads has been indispensable for civilizations from past to present. The geographies and civilizations where the roads were built played an important role in the construction of the road, ensuring its continuity and gaining an identity. The aim of this study is to reveal the construction process of the Kırkdilim road, which has been under construction for more than half a century, how it turned into a tainted road in the historical process, and the reflections of the political decisions taken in the field. For this purpose, field studies were carried out at intervals between 2018-2022. During these studies, interviews consisting of open-ended questions were conducted with the local people. The results of the research revealed that the effect of the geological and geomorphological structure in the area, technical inadequacies and political decisions are among the biggest reasons why the Kırkdilim road could not be completed for more than half a century in the historical process. Due to the slope conditions of the Mesozoic limestones and conglomerate formations in the area, their mobility is high. Tunnels and roads built in the area in previous years have become unusable due to landslides and rockfalls, and many fatal accidents have occurred. The historical process, especially the reflections of the political decisions taken, has made the Kırkdilim road a tainted place. The experiences, narratives and stories of the people who use this tainted area have been passed down from generation to generation. Today, the area is a tainted place both in terms of local people, drivers and passengers using the area, aesthetically and archaeologically, and politically.

Deformation of the European Plate (58-0 Ma): Evidence from Calcite Twinning Strains

We present a data set of calcite twinning strain results (n = 209 samples; 9919 measured calcite twins) from the internal Alpine nappes northwestward across the Alps and Alpine foreland to the older extensional margin along the Atlantic coast in Ireland. Along the coast of Northern Ireland, Cretaceous chalks and Tertiary basalts are cross-cut by calcite veins and offset by calcite-filled normal and strike-slip faults. Both Irish sample suites (n = 16 with four U-Pb vein calcite ages between 70–42 Ma) record a sub-horizontal SW-NE shortening strain with vertical extension and no strain overprint. This sub-horizontal shortening is parallel to the margin of the opening of the Atlantic Ocean (~58 Ma), and this penetrative fabric is only observed ~100 km inboard of the margin to the southeast. The younger, collisional Alpine orogen (~40 Ma) imparted a stress–strain regime dominated by SE-NW sub-horizontal shortening ~1200 km northwest from the Alps preserved in Mesozoic limestones and calcite veins (n = 32) in France, Germany and Britain. This layer-parallel shortening strain (−3.4%, 5% negative expected values) is preserved across the foreland in the plane of Alpine thrust shortening (SE-NW) along with numerous outcrop-scale contractional structures (i.e., folds, thrust faults). Calcite veins were observed in the Alpine foreland in numerous orientations and include both a SE-NW layer-parallel shortening fabric (n = 11) and a sub-vertical NE-SW vein-parallel shortening fabric (n = 4). Alpine foreland strains are compared with twinning strains from the frontal Jura Mountains (n = 9; layer-parallel shortening), the Molasse basin (n = 26; layer-parallel and layer-normal shortening), Pre-Alp nappes (n = 39; layer-parallel and layer-normal shortening), Helvetic and Penninic nappes (Penninic klippe; n = 46; layer-parallel and layer-normal shortening plus four striated U-Pb calcite vein ages ~24 Ma) and calcsilicates from the internal Tauern window (n = 4; layer-normal shortening). We provide a chronology of the stress–strain history of the European plate from 58 Ma through the Alpine orogen.

Karst relief of the Mali me Gropa Massif, central Albania

The mid-altitude mountain massif of Mali me Gropa is located in the central part of Albania, rises to an altitude of 1500–1800 m a.s.l., is composed mostly of Mesozoic limestone, and is characterized by extensive surface karst development. The karst relief is dominated by “doline” morphology including “polygonal” karst. Detailed geomorphological analysis of the western part of the Mali me Gropa massif (so-called Western Massif) by means of GIS methods is used to determine and explain the morphometric and morphological diversity of the area’s topography. Based on a homogeneity criterion, a number of geomorphological units with specific kinds of karst relief have been distinguished within the massif. The differences in karst sculpture concern the size (diameter) of dolines and depressions, their depth, shape and symmetry, orientation, density of occurrence and spatial pattern, which provide the basis for distinguishing geomorphological units. The spatial differentiation of the karst relief is explained by the influence of factors which are evolutionary (geological and geomorphological evolution of the massif), hypsometric (altitude difference of terrains) and geomorphologic-structural (inclination of the slopes and layers). The relatively poor expression of open karst conduits (i.e. caves and vertical shafts) on the surface of the massif may result from the relative immaturity of the epikarst zone, the widespread occurrence of residual cover on the plateau, and the accumulation of large amounts of clay material in dolines and depressions. Detailed hydrogeological studies show, however, high karst permeability and dominance of conduit flow. Considering the high geomorphological landscape and ecological value of the area, it should be granted the status of a nature reserve or national park. Geomorphological and karstological research within the massif should be continued as it represents a type of karst found also in other parts of Albania. This type of karst area is of great economic (groundwater reserves) and natural protection (environmental) importance.

Supergénna mineralizácia na II. horizonte Východnej šachty hnedouhoľnej bane Handlová (Slovenská republika)

At the II. horizon of the Eastern shaft of Handlová coal mine the occurrence of mineral assemblage of secondary minerals was identified. These accumulations consist of sulphate group minerals confirmed by PXRD and semiquantitative chemical analysis (EDS), namely gypsum, alunogen, pickeringite, melanterite, sideronatrite and epsomite. Sulphates form coatings, crystalline crusts and aggregates, which crystallized on the walls of mine corridors. The dimensions of these accumulations are reaching approximately 1.5 x 1.3 m with thickness up to 5 cm. The refined unit-cell parameters of alunogen (for the triclinic space group P-1) are: a 7.413(1), b 26.944(4), c 6.051(1) Å, α 90.05(1), β 97.65(1), γ 91.82(1)°, V 1197.1(3) Å3, pickeringite (for the monoclinic space group P21/c): a 6.1808(8), b 24.252(2), c 21.220(2) Å, β 100.36(1)°, V 3128.8(6) Å3 and melanterite (for the monoclinic space group P21/c): a 14.022(5), b 6.503(2), c 10.945(4) Å, β 105.83(3)°, V 960.2(7) Å3. Sideronatrite and epsomite were identified in mixture with the most significant diffraction maxima for sideronatrite: 10.252/100, 4.905/37, 3.424/10, 3.067/9 and epsomite: 5.347/18, 5.302/18, 4.489/26, 4.215/100, 4.201/59, 2.880/24, 2.747/23, 2.677/18. Accumulations of minerals were formed on the mine walls. Secondary sulphates are considered as products of the weathering of Fe-rich carbonates, pyrite and other sulphidic minerals which are part of associated pelosiderites embedded in the clays and claystones. Locally, gypsum and hexahydrite were also identified in the form of transparent crystals and white powdery aggregates on the calcite speleothems genetically linked to Mesozoic limestones and gypsum-rich Lower Triassic Werfen Formation. Unit-cell parameters refined from X-ray powder diffraction data are for hexahydrite (for the monoclinic space group C2/c): a 10.107(1), b 7.2114(8), c 24.424(3) Å, β 98.28(1)°, V 1761.7(3) Å3.

The Coume Ouarnède System, a Hotspot of Subterranean Biodiversity in Pyrenees (France)

Located in Northern Pyrenees, in the Arbas massif, France, the system of the Coume Ouarnède, also known as Réseau Félix Trombe—Henne Morte, is the longest and the most complex cave system of France. The system, developed in massive Mesozoic limestone, has two distinct resurgences. Despite relatively limited sampling, its subterranean fauna is rich, composed of a number of local endemics, terrestrial as well as aquatic, including two remarkable relictual species, Arbasus caecus (Simon, 1911) and Tritomurus falcifer Cassagnau, 1958. With 38 stygobiotic and troglobiotic species recorded so far, the Coume Ouarnède system is the second richest subterranean hotspot in France and the first one in Pyrenees. This species richness is, however, expected to increase because several taxonomic groups, like Ostracoda, as well as important subterranean habitats, like MSS (“Milieu Souterrain Superficiel”), have not been considered so far in inventories. Similar levels of subterranean biodiversity are expected to occur in less-sampled karsts of central and western Pyrenees.

A model for the formation of the Pradol (Pradolino) dry valley in W Slovenia and NE Italy

In tectonically active mountain ranges, the landscape is shaped by the interplay of erosion/sedimentation and tectonically driven crustal deformation. Characteristic landforms such as moraines, wind gaps, fault scarps, and river terraces can be used to decipher the landscape evolution. However, the available data often allow for different interpretations. Here we study the Pradol (Pradolino) Valley in Western Slovenia, a deeply incised canyon whose floor rests several hundreds of metres above the surrounding valleys. We use high-resolution digital elevation models, geomorphic indices and field observations to unravel the evolution of this peculiar landform. We present a six-stage evolution model of the canyon that includes the blockage of valleys by advancing glaciers, river diversion, and rapid incision due to a high discharge of post-glacial meltwater. The formation of the Pradol Valley was most likely facilitated by an underlying fault that serves as an easily erodible weakness zone in the Mesozoic limestones. Our model indicates that the formation of the canyon could have occurred during the last glaciation, which results in incision rates of several cm/yr. With the proposed model we can explain all remote and field observations available. Our study shows that a complex interplay of different landscape-shaping processes is needed to explain the occurrence of the Pradol dry valley and that rapid changes in the morphology occurred after the last glacial maximum.

Directional analysis of drainage network and morphotectonic features in the south-eastern part of Bükk Region

The fracture deformations often result in linear morphological elements (lineaments, valleys) on the surface. In many cases, the direction of the lineaments and valleys can be well followed by the strike of the geological structural elements. Therefore, conclusions can be drawn from these directions for regional tectonic processes. Our work aimed to analyse the relationship between the valley and lineament network and the structural elements in the south-eastern part of Bükk Region. We prepared the theoretical drainage network map and lineament map of the area. The direction of the linear elements was examined separately on the eastern part of South-Eastern Bükk that is built up mainly by Mesozoic limestone and the eastern side of Bükkalja area covered by Neogene and Quaternary sediments. Structural geological surveys were also performed on seven sites to measure the strike of joint sets. These results were compared with the valleys’ direction in the 2 km wide area of the measurement sites. Based on our results, it can be stated that the development of the drainage network was influenced by the geological elements; however, there are local differences in the characteristics of the South-Eastern Bükk and Bükkalja. Our study confirmed that the study of linear morphological elements has great importance in the exploration of geological structural elements.

The Velardeña Zn–(Pb–Cu) skarn-epithermal deposits, central-northern Mexico: New physical-chemical constraints on ore-forming processes

The Velardeña mining district is economically the most important of Durango state. The ore deposits occur in different skarn zones developed within the intrusive contact between Mesozoic limestones and Eocene granitic stocks and dikes. The most important ore deposits are related to the Santa María dike and Reyna de Cobre porphyritic stock (separated from each other by 10 km). They occur as irregularly shaped replacement masses developed near the intrusive contact and have a skarn paragenesis dominated by calc-silicates and sulfides. The mineral assemblages show replacement textures and are dominated by calcic clinopyroxene (Di97-53Hd42-02Jh04-01) and garnet (Ad100-57Grs43-00) in the exoskarn, with wollastonite particularly abundant in the endoskarn. Hydrous silicates are actinolite, epidote, and chlorite, whereas sulfides include pyrite, sphalerite, pyrrhotite, galena, chalcopyrite, and sulfosalts. Scheelite, hematite, quartz, and calcite are also present. According to sphalerite geobarometry, the skarns formed at hypabyssal depths (~3–4 km). They developed by a succession of replacive mineralizing events, including (a) a prograde stage at temperatures from ≥470 to 335 °C in conditions of low f (CO2), followed by (b) a retrograde stage from 335 to 220 °C. There was a general increase in f (O2), accompanying the temperature decline during the formation of the system, which accounts for a process of mixing with cooler, oxidizing, and dilute water. During the retrograde stage, wollastonite, calcic garnet and clinopyroxene formed. On the other hand, hydrous silicates, sulfides, sulfosalts, scheelite, and hematite crystallized during the retrograde stage. Skarn mineralization is crosscut by veins of calcite, fluorite, adularia, and sphalerite. The vein mineralization formed at temperatures below 200 °C. The different ore deposits of Velardeña constitute a telescoped skarn–epithermal mineral system.

Geological setting and lithological inventory of the Czarna Woda conglomerates (Magura Nappe, Polish Outer Carpathians)

During the late Oligocene to early Miocene the residual Magura Basin was located along the front of the Pieniny Klippen Belt (PKB). This basin was supplied with clastic material derived from a south-eastern direction. In the Małe (Little) Pieniny Mts. in Poland, the late Oligocene/ early Miocene Kremna Fm. of the Magura Nappe (Krynica subunit) occurs both in front of the PKB as well as in the tectonic windows within the PKB. Lenses of exotic conglomerates in the Kremna Fm. contain frequent clasts of Mesozoic limestones (e.g. limestones with “filaments” microfacies and Urgonian limestones) and Eocene shallow-water limestones. Fragments of crystalline and volcanic rocks occur subordinately. The provenance of these exotic rocks could be probably connected with Eocene exhumation and erosion of the SE part of the Dacia and Tisza Mega-Units.

Crystal Chemistry of Barian Titanian Phlogopite from a Lamprophyre of the Gargano Promontory (Apulia, Southern Italy)

This study is focused on a barian titanian phlogopite found in an alkaline ultramafic dyke transecting Mesozoic limestones of the Gargano Promontory (Apulia, Italy). The rock containing the barian titanian phlogopite, an olivine-clinopyroxene-rich lamprophyre with nepheline and free of feldspars, has been classified as monchiquite. The present study combines chemical analyses, single crystal X-ray diffraction and Raman spectroscopy. Chemical variations suggest that the entry of Ba into the phlogopite structure can be explained by the exchange Ba + Al = K + Si. The crystal structure refinement indicates that the Ti uptake is consistent with the Ti–oxy exchange mechanism. The structural parameters associated with the oxy substitution mechanism are extremely enhanced and rarely reported in natural phlogopite: (a) displacement of M2 cation toward the O4 site (~0.7); (b) M2 octahedron bond-length distortion (~2.5); (c) very short c cell parameter (~10.14 Å). Raman analysis showed most prominent features in the 800–200 cm−1 region with the strongest peaks occurring at 773 and 735 cm−1. Only a weak, broad band was observed to occur in the OH-stretching region. As concerns the origin of the barian titanian phlogopite, the rock textural features clearly indicate that it crystallized from pockets of the interstitial melt. Here, Ba and Ti enrichment took place after major crystallization of olivine under fast-cooling conditions, close to the dyke margin.

DEPOSITI DELTIZI PLIOCENICI ALLO SBOCCO DELLA VAL BREMBANA (PREALPI BERGAMASCHE)

At the outlet of the Brembo valley into the upper Lombardy Plain a conglomerate unit is present, about 30 m thick and outcropping over an area of about 1.5 km 2 . This conglomerate was in the past attributed to the Villafranchian and considered as the lowermost part of the "Ceppo", a thick and widespread formation composed of well cemented coarse fluvial deposits.
 The conglomerate unit here described, called Madonna del Castello Conglomerate, is interpreted as a Late Pliocene deltaic deposit. It shows a large scale cross—stratification affecting the whole thickness of the unit; single beds show decreasing gradient from the top to the base, with a concave up profile. Beds are prevailingly composed of matrix supported conglomerate, with elongated clasts parallel to the dip of bedding. Both geometry and structures are indicative of foreset beds.
 The petrographic composition of the Madonna del Castello Conglomerate is characterized by prevailing clasts of Mesozoic limestones of local provenance, while subordinate and often absent are metamorphic, volcanic and arenaceous rocks deriving from the Sudalpine crystalline basement and from its Paleozoic cover, which outcrop at the head of the Brembo valley.
 The Madonna del Castello Conglomerate overlies Early to Middle Pliocene fossiliferous mudstones (Tornago Formation) and represents a terminal regressive phase of the marine Pliocene sedimentation at the foot of the Lombardy Prealps.

Witnesses of the early Pliocene sea-level rise in the Manilva Basin (Málaga, S Spain)

The Sierra de la Utrera, a relief in the Manilva Basin (Málaga, SW Spain), shows bored surfaces at different heights above present-day sea level, from 96 m to 287 m. Borings occur in the eastern, central, and western parts of the Canuto de la Utrera, a prominent gorge in the central southern part of the relief excavated in Mesozoic limestones, as well as on the western end of the Canuto Chico, a smaller canyon in the northern part. Pliocene marine deposits fossilized the bored surfaces. Bored boulders of the substrate are embedded in the Pliocene sediments. The traces Gastrochaenolites ispp., Entobia ispp., Caulostrepsis ispp., Circolites kotoucensis, and Ericichnus asgaardi have been identified. Among these, Caulostrepsis is found only in the reworked blocks. This ichnoassemblage, attributed to the archetypical Entobia Ichnofacies of rocky shores, represents boring activity in high-energy, very-shallow-water settings, close to the sea level, and with a virtually null sedimentation rate. The vertical distribution of bored surfaces attests to a progressive sea-level rise. The onlap of the Pliocene deposits on the substrate is consistent with the deepening trend. Planktonic foraminiferal assemblages collected from the sediment adjacent to the Sierra de la Utrera demonstrate that boring activity spanned, at most, 1 Ma during the early Pliocene, Zanclean (biozones MPl 1 and MPl 2), ranging from 5.33 to 4.36 Ma.

Geothermal Waters in Pamukkale as an Hydrogeological Model within the Menderes Massif, Turkey

The area is located in the northern shoulder of the eastern part of the E-W trending continental rift zone of the Büyük Menderes and consists of Paleozoic rocks, Mesozoic limestones and sedimentary rocks in age of Eocene, Pliocene and Quaternary. The marbles, quartzites and carbonate rocks, limestones, sedimentary rocks, alluvium and travertine deposits are of passable rocks for geothermal waters. Geothermal waters of Pamukkale show outlet temperatures ranging from 35 to 48 °C and reservoir temperatures of between 150 and 180 °C and are of Mg-Ca-SO4-HCO3 type waters. Geothermal waters in Pamukkale are distinguished by Mg>Ca>Na+K as dominant cations and HCO3>SO4> Cl as dominant anions. The diagram of Na1/1000-K1/100-√Mg shows that the samples of Pamukkale are of immature waters. Finally, the geothermal waters in Pamukkale were represented as a hydrogeological model.

Geothermal Waters of Urganli (Manisa) as a Hydrogeological Model, Western Anatolia, Turkey

The area of Urganlı is located in the western part of Gediz graben and consists of Paleozoic metamorphic rocks with intercalations of various schists and marbles, Mesozoic limestones and ultrabasic rocks, and Pliocene to recent travertine deposits and alluviums. Mica schists as intercalations in Paleozoic metamorphic rocks form impermeable basement rocks hydrogeochemically. The marble as intercalations in metamorphic rocks is of reservoir rock for geothermal waters. Moreover, these marbles are also aquifer for groundwaters. As impermeable rocks, sedimentary rocks with high quantities of clay contents in Pliocene to recent age play an essential role for enhancement of geothermal waters. Geothermal waters of Urganlı with temperatures of up to 75 °C and reservoir temperatures of up to 180 °C are of Na-HCO3 type whereas groundwaters display Ca-Mg-HCO3 type. Geothermal waters of Urganlı were represented as an hydrogeological model within this study. The Kula volcano in the Gediz rift zone with a last eruption age up to 18,000 a is responsible for heating geothermal waters.

Pore space properties in carbonate fault rocks of peninsular Italy

The fault cores of extensional faults in Mesozoic limestones and dolostones are examined by mean of combined microstructural, ultrasonic and petrophysical analyses. Grain-supported fault rocks commonly localize in the outer fault cores, whereas matrix-supported fault rocks in their inner portions. Cemented fault rocks, if present, surround the main slip surfaces. All dolomite-rich fault rocks, include elongated pores that show a preferential orientation only in the inner fault core. On the contrary, the pore network of calcite-rich fault rocks is made up of elongated pores in the outer fault core, and of sub-spherical pores in the inner fault core. Despite their different pore network characteristics, the petrophysical values of both grain-supported and matrix-supported fault rocks are quite similar one another, with effective porosity up to 10–12%, and permeability up to 2–5 mD. Differently, these values drop down to host rock values, porosity ~5% and permeability ~10−3 mD, in the cemented fault rocks. Experimental data are discussed to establish, for the first time, the relative control exerted by individual cataclastic and diagenetic processes on the present day pore characteristics, and to decipher the fault core permeability structure at depth.

Faulting and Gas Discharge in the Rome Area (Central Italy) and Associated Hazards

AbstractThe area of Central Italy around Rome contains natural gas discharging zones and several others where quarrying or mining excavation removed the impervious superficial layers allowing a free hazardous discharge to the surface of endogenous gas. These gas manifestations are mostly located above buried structural highs of fractured Mesozoic limestones hosting the main regional aquifer and revealed by gravity anomalies. In the last decades, many gas blowouts occurred in this area, from wells whose depth ranged from 10–15 to 350 m. The main component of the emitted gas is CO2 with minor H2S; only in a blowout offshore of Fiumicino CH4 prevailed. Several animals even of large size and two persons were killed by the emitted gas (mostly by H2S), and nearby houses were evacuated because of dangerous indoor CO2 concentrations. He and CO2‐carbon isotopes suggest that gas has a deep mantle signature, as indicated for Fiumicino gas by N2 isotopic composition and N2/36Ar ratios. Gas rising from depth first accumulates in the buried Mesozoic limestone reservoir, and from there it escapes along deep‐reaching faults. On its way to the surface, the gas dissolves into and pressurizes any encountered confined aquifer, which may then produce a gas blowout when reached by wells. The main direction of the gas feeding faults was estimated through the alignment of visible gas emissive points, the shape of the positive anomalies in soil CO2 flux maps, and new structural‐geological observations, finding that they correspond mostly to the main orientation of the underlying limestone structural high.