Andrea Columbu

Università di Pisa | UNIPI · Department of Earth Sciences

Chemical and physical proxy data from a precisely dated early last glacial (~113e110 ka, MIS5d) Sardinian stalagmite reveal a sub-millennial-scale, cool-dry climate event centered at 112.0 þ0.52 /-0.59 ka, followed by a rapid return to warm-wet conditions at 111.76 þ0.43 /-0.45 ka. Comparison with regional speleothem records and the palaeotemperatu...

Here we present the first record of Marine Isotope Stage (MIS) 7 from Sardinia, based on a U-Th-dated speleothem from Crovassa Azzurra cave, which also grew during MIS 5. Carbonate precipitation was continuous during MIS 7, while two multi-millennial hiatuses interrupted growth during MIS 5. These hiatuses occurred during times of unstable climate,...

The causes of Neanderthal–modern human (MH) turnover are ambiguous. While potential biocultural interactions between the two groups are still little known, it is clear that Neanderthals in southern Europe disappeared about 42 thousand years ago (ka) after cohabitation for ~3,000 years with MH. Among a plethora of hypotheses on Neanderthal extinctio...

Similarly to the effects of current climate change, the last deglaciation (Termination I) rapidly altered northern latitude temperatures and ice-sheet extent, as well as the Atlantic Meridional Overturning Circulation. However, it is still unclear how these changes propagated and impacted the central Mediterranean continental rainfall variability....

A multiproxy record from a stalagmite collected from Torgashinskaya Cave (Southern Siberia, Russia) and growing between ca. 6 and 3.8 ka shows evidence for regional climatic changes occurring at ca. 5 ka. Interpretation of stable isotope ratios (δ18O and δ13C) and fluorescence data (intensity and wavelength of the emitted fluorescence) suggests tha...

Il sistema carsico di Toirano (Liguria) comprende diverse grotte, tra cui le-lombo (247 m s.l.m.), di Santa Lu-cia Superiore o del Santuario (215 m s.l.m.) e Inferiore (201 m s.l.m.), e la Grotta della Bàsura (186 m s.l.m.). In passato la genesi del sistema di grotte-to il reticolo di gallerie freatiche, impo-state sulle maggiori direttrici struttu...

Palaeoclimate research based on speleothems from several Apulian caves reconstructing the changes occurred during Neanderthal-Modern Human transition.

Riassunto In Emilia-Romagna il processo carsico si sviluppa prevalentemente nelle rocce evaporitiche (gessi). Come scoperto da ricerche recenti, il ciclo speleogenetico solo dal contesto strutturale locale, ma anche dalle oscillazioni climatiche tardo quaternarie che hanno modellato il paesaggio esterno. Il Progetto "Evolgyps" si propone di ampliar...

Paleoclimate information on multiple climate variables at different spatiotemporal scales is increasingly important to understand environmental and societal responses to climate change. A lack of high-quality reconstructions of past hydroclimate has recently been identified as a critical research gap. Speleothems, with their precise chronologies, w...

Ice core records from Greenland provide evidence for multiple abrupt cold-warm-cold events recurring at millennial time scales during the last glacial interval. Although climate variations resembling Dansgaard-Oeschger (DO) oscillations have been identified in climate archives across the globe, our understanding of the climate and ecosystem impacts...

The last deglaciation (Termination I) saw rapid northern latitude temperature changes and ice-sheet loss, coupled with changes in the Atlantic Meridional Overturning Circulation. However, the modes, timing and sustaining mechanisms that propagated these changes to the Mediterranean region are far from well understood. Here, we compare two high-reso...

Present climate conditions impede the formation of calcite speleothems in the gypsum caves of the semi-arid region of Sorbas (Southern Spain). However, U-Th dating reveals the uninterrupted deposition of a 46 mm-thick carbonate flowstone in the Sorbas caves from ~78 to ~71 ka, during Marine Isotope Stage (MIS) 5a. This indicates that the area was v...

This study reports the results of a comprehensive radiometric dating campaign carried out on 51 speleothems from caves in Apulia and Sardinia during the last ~7 years. Around 230 ages were produced by exploiting the U-Th method. Sampling targeted 5 caves in Apulia and 12 caves in Sardinia. All caves are located ~41˚N (±1˚) latitude, representing an...

Several caves in orthoquartzite or metaquartzite lithologies have been explored in South America in recent years. Even if the host rock is usually over 90% quartz, with very few other mineral components, surprisingly, these caves host remarkable and diverse secondary mineral deposits. Their presence poses a range of questions regarding minerogenesi...

Our understanding of climate dynamics during millennial-scale events is incomplete, partially due to the lack of their precise phase analyses under various boundary conditions. Here we present nine speleothem oxygen-isotope records from mid-to-low-latitude monsoon regimes with sub-centennial age precision and multi-annual resolution, spanning the H...

In the last decade several researchers have tried to understand the role of microbes in the deposition of silica speleothems. In this work we present the most recent advances in this effort, obtained through the study of two different ecological niches: the transition from quartz-sandstone to amorphous silica in 1) cave walls and on 2) cave floors...

Colombo Cave is part of Toirano karst system and opens at 247 m a.s.l. The wide entrance passage was used during prehistoric times, and a 4.5 m deep archaeological excavation pit is located 10 m from the entrance. The main room is dominated by a large central rock pillar and the floor is completely covered by important ancient bat guano deposits. S...

The Toirano karst system comprises different caves between altitudes of 340 m and 186 m asl. A detailed investigation of cave pattern, morphologies and of the sedimentary deposits attributes the origin of the caves to rising waters that followed the main vertical structural pathways. Many walls and roofs are sculpted with rising features (cupola an...

Speleothems show an array of shapes. Flowstones are commonly tabular sheet-like deposits, which cover cave floors and walls. They can procure detailed information about past hydrogeological conditions through their morphology, geochemical composition and stratigraphic properties, which in turn are related to the climate conditions at the surface. T...

Collapse is a common geomorphic process in karst areas, especially on the Yunnan-Guizhou Plateau, which has a tectonic background of integral uplift. The frequent occurrence of collapse processes in karst underground caves and canyons indicates that collapses play an important role in the formation of canyons. Through an analysis of the morphology...

The last deglaciation (Termination I, T-I) was the most recent global-scale climate transition. It involved a drastic temperature increase guiding massive melting of ice sheets, with a concurrent reorganization of inter- and intrahemispherical atmospheric and ocean circulation patterns. T-I lasted ~3.0 ka (ka = kiloyears before present) in Greenlan...

In Sardinia, precisely dated Holocene climate and environmental records are derisory. Indeed, availability of lacustrine sediments is scarce, because this Island has one natural relatively large lake only. Accordingly, the most comprehensive Holocene lake-based climate reconstruction, spanning the last 8000 years, has been published only recently (...

Caves are dark subsurface environments with relatively constant temperatures that allow studying bio-mineralization processes and paleoenvironmental or climate changes in optimal conditions. In the extreme and oligotrophic cave environment, manganese patinas having stromatolite-like features are uncommon. Here we provide the first detailed mineralo...

We present the first stable isotope (δ13C and δ18O) speleothem record from continental Croatia retrieved from two coeval stalagmites from Nova Grgosova Cave. U-Th dates constrain the stalagmite growth history from 10ka to the present, revealing coeval growth between 7.8 and 5.6ka. We interpret δ18O as an autumn/winter hydrological proxy related to...

The concept of geoheritage is related to places of geological interest, generally of aesthetic, cultural, socioeconomic and/ or scientific value. Many geosites are of karstic nature, because of their intrinsic beauty, their singularity and high geodi-versity. Caves are among the most visited and economically exploited geological landforms. They con...

Raponzolo is a paleo-phreatic cave explored in 2011 in the Brenta Dolomites (Trentino, Italy), at the remarkable altitude of 2,560 m a.s.l. Differently to all other caves of the area, it hosts well-cemented fine to medium sands of granitic-metamorphic composition. The composition suggests a sediment source from the Adamello and Tonale Unit, separat...

After the last interglacial [Marine Isotope Stage (MIS) 5e] Europe was affected by several harsh climatic oscillations. In this context southern Italy acted, like the rest of peninsular Mediterranean Europe, as a 'glacial refugium', allowing the survival of various species, and was involved in the spread of 'cold taxa' (e.g. woolly mammoth and wool...

In Europe, the scarcity of last glacial speleothem palaeoclimate/palaeoenvironmental records is attributable to the generally dry and cold climate that hampered soil bioproductivity, karst dissolution and carbonate deposition in caves. However, at southern Mediterranean latitudes, glacial climate was milder than in central or northern Europe and sp...

The orthoquartzite Imawarì Yeuta cave hosts exceptional silica speleothems and represents a unique model system to study the geomicrobiology associated to silica amorphization processes under aphotic and stable physical–chemical conditions. In this study, three consecutive evolution steps in the formation of a peculiar blackish coralloid silica spe...

The Toirano karst system is located in the Ligurian Alps (north Italy), around 4.5 km inland from the coastline and carved in Middle Triassic dolostone. It comprises five cave levels over a 154 m altitudinal range, specifically Ulivo (340 m a.s.l.), Colombo (247 m a.s.l), Upper Santa Lucia (215 m a.s.l.), Lower Santa Lucia (201 m a.s.l.) and Bàsura...

Data supporting Comas-Bru et al., 2020 (ESSD): https://doi.org/10.5194/essd-12-2579-2020

Characterizing the temporal uncertainty in palaeoclimate records is crucial for analysing past climate change, correlating climate events between records, assessing climate periodicities, identifying potential triggers and evaluating climate model simulations. The first global compilation of speleothem isotope records by the SISAL (Speleothem Isoto...

In questo articolo presentiamo le analisi petrografiche, degli isotopi stabili dell'ossige-no (δ 18 O) e del carbonio (δ 13 C) e uranio-torio (U-Th) di tre stalagmiti cresciute nel sistema carsico dei piani Eterni (all'interno del parco Nazionale Dolomiti Bellunesi), ai fini di una ricostruzione paleoclimatica-ambientale di quest'area di alta monta...

Abstract. Characterising the temporal uncertainty in palaeoclimate records is crucial for analysing past climate change, for correlating climate events between records, for assessing climate periodicities, identifying potential triggers, and to evaluate climate model simulations. The first global compilation of speleothem isotope records by the SIS...

Meghalaya (NW India) is one of the regions in the world with highest recorded rainfalls. Because of these peculiar climatic conditions and intense solutional weathering, karstic caves are widely reported in the numerous limestone areas of this part of India. Likewise, the extremely high rainfall and the tropical monsoon climate have fostered the fo...

Gypsum (CaSO 4 •2H 2 O) speleothems (i.e. stalactites, stalagmites, etc.) in caves form frequently through dissolution of the gypsum host-rock by seepage water and subsequent secondary mineral re-precipitation from gypsum-saturated solutions [1]. Gypsum takes its structurally-bound hydration water (GHW) from the liquid; the isotopic composition (δ...

Although quantitative isotope data from speleothems has been used to evaluate isotope-enabled model simulations, currently no consensus exists regarding the most appropriate methodology through which to achieve this. A number of modelling groups will be running isotope-enabled palaeoclimate simulations in the framework of the Coupled Model Intercom...

Quartz sandstone of the Sarisariñama massif in Venezuela hosts the world biggest collapse dolines in quartz-rich lithologies, with volumes up to some millions of cubic meters. Due to extremely complex logistics required to reach the massif, the genesis of these depressions and of the underlying caves has never been studied in detail. The lack of fi...

High-resolution U-Th and 14C dating of two calcite flowstones (RTf: Last Interglacial; RTy: Late Holocene) from the Re Tiberio – Monte Tondo karst system (North Italy) is presented to investigate the palaeoclimate potential of speleothems from gypsum caves. To date, there is a lack of information regarding the dating potential of calcite speleothem...

Although quantitative isotopic data from speleothems has been used to evaluate isotope-enabled model simulations, currently no consensus exists regarding the most appropriate methodology through which achieve this. A number of modelling groups will be running isotope-enabled palaeoclimate simulations in the framework of the Coupled Model Intercompa...

Western Europe is the region with the highest density of published speleothem δ18O (δ18Ospel) records worldwide. Here, we review these records in light of the recent publication of the Speleothem Isotopes Synthesis and AnaLysis (SISAL) database. We investigate how representative the spatial and temporal distribution of the available records is for...

Chemical mobility of crystalline and amorphous SiO2 plays a fundamental role in several geochemical and biological processes, with silicate minerals being the most abundant components of the Earth’s crust. Although the oldest evidences of life on Earth are fossilized in microcrystalline silica deposits, little is known about the functional role tha...

Western Europe is the region with the highest density of published speleothem δ18O (δ18Ospel) records worldwide. Here we review these records in light of the recent publication of the Speleothem Isotopes Synthesis and Analysis (SISAL) database [1]. We investigate how representative the spatial and temporal distribution of the available records is f...

Stalagmites are valuable Quaternary palaeoclimate archives because: 1) cave calcite dating is highly precise and accurate; 2) geochemical (oxygen and carbon stable isotopes, trace elements, etc.) and physical (growth rate, fabric, shape and size, etc.) properties are often related to environmental changes at the surface, such as rainfall and temper...

This ambitious proposal rests on the hypothesis that by characterising the palaeo-karst systems located in topographic barriers, we may quantify the contribution of underground conduits to the exchange between marine basins situated on opposite sides of the barrier, at times of different base-levels. The aim of this project is to reconstruct the dr...

observations using terrestrial laser scanning and 3D photogrammetry in a gypsum cave Abstract Terrestrial Laser Scanning (TLS) and 3D photogrammetry techniques were used in a relatively small (100-m-long) cave developed in Messinian gypsum in Emilia-Romagna (N. Italy). The surveys were carried out to compare the results obtained by both methods in...

Here we track the water-table position and temperature of the Mount San Giovanni aquifer (Iglesiente-Sulcis mining district, SW Sardinia, Italy) during the past 600 ka by determining the ages (U/Th dating) and stable isotope compositions (δ¹⁸O, δ¹³C and Δ47) of a variety of subaqueous carbonate speleothems (e.g. calcite spars, dogtooth calcite crys...

Stable isotope records from speleothems provide information on past climate changes, most particularly information that can be used to reconstruct past changes in precipitation and atmospheric circulation. These records are increasingly being used to provide “out-of-sample” evaluations of isotope-enabled climate models. SISAL (Speleothem Isotope Sy...

Cave exploration is feasible by only a minimal number of well-trained geologists. However, underground environments can be considered as excellent natural laboratories for the study of multiple disciplines among the Earth Sciences, such as geomorphology, minero-petrography, geochemistry, palaeoclimate, tectonics, meteorology, geomicrobiology, seism...

A flight of marine terraces along the Cuban coast records Quaternary sea‐level highstands and a general slowly uplifting trend during the Pleistocene. U/Th dating of these limestone terraces is difficult because fossil reef corals have been affected by open system conditions. Terrace ages are thus often based on geological and geomorphological obse...

Caves carved in Tepui quartz-sandstone table mountains (Venezuela) are among the most unexplored and untouched places on Earth. For example, the ~20 km-long Imawarì Yeuta cave has been discovered and explored only in 2013. Hosted in the Precambrian rocks of the Auyan Tepui massif, it is now considered one of the longest quartz-sandstone cave system...

More than 600 caves have been surveyed in the Triassic and Messinian gypsum beds of the Northern Apennines (Emilia-Romagna region, N Italy). Despite the fact that these caves have been studied for a very long time, their age was inaccurately believed to be Late Glacial. In fact, the fast dissolution of gypsum and the regional uplift of the mountain...

Piani Eterni is the deepest and longest multilevel karst system of the Dolomites. The geometric distribution and stratigraphic-structural guidance of palaeo-epiphreatic levels have been studied in detail in recent times, but there are still several open questions regarding the palaeoclimatic and palaeogeographic factors that have controlled its evo...

Although outcropping rarely in Italy, evaporite (gypsum and anhydrite) karst has been described in detail since the early 20 th century. Gypsum caves are now known from almost all Italian regions, but are mainly localised along the northern border of the Apennine chain (Emilia Romagna and Marche), Calabria, and Sicily, where the major outcrops occu...

Gypsum beds host the majority of the caves in the north-eastern flank of the Apennines, in the Emilia Romagna region (Italy). More than six hundred of these caves have been surveyed, including the longest known epigenic gypsum cave systems in the world (Spipola-Acquafredda, ~11 km). Although this area has been intensively studied from a geological...

Carbonate speleothems record a series of environmental and climatic information (McDermott, 2004). Their mere presence in a cave signifies that water was present in the karst system and conditions were adequate to stimulate supersaturation with respect CaCO3. The most exploited geochemical proxies are oxygen (δ18O) and carbon (δ13C) stable isotopes...

Triassic and Messinian gypsum beds host the majority of the caves in the eastern flank of the northern Apennines. To date, more than six hundreds voids have been mapped, including the longest known epigenic gypsum cave system in the world (Spipola-Acquafredda, ~11 km of tunnels) (De Waele et al., 2013). Superimposed caves are typically sub-horizont...

Gypsum caves are uncommon environments for carbonate speleothems (cave deposits). Contrary to limestone caves, the only source of non-atmospheric carbon is from biogenic CO2 produced by the overlying soils. Enhanced CO2 content in soils is in turn related with climate, where warm temperatures and high humidity favour plant activity (Fairchild and B...

The North Atlantic Oscillation (NAO) is the most prominent atmospheric system operating in the Northern Hemisphere, controlling the intra-centennial intensity of westerly winds and the distribution of moisture and heat across Europe and the Western Mediterranean Basin (Hurrell et al., 2003). The Mediterranean area is in fact considered one of the m...

Although occupying a critical position at the center of the Mediterranean Sea, the Island of Sardinia (Italy) has never been the focus of multi proxy data-based palaeoclimate studies. An excellent way to obtain information about late Quaternary terrestrial climate oscillations in the region is the study of carbonate speleothems, because they allow...

Detailed geomorphological analysis has revealed that subhorizontal gypsum caves in the Northern Apennines (Italy) cut across bedding planes. These cave levels formed during cold periods with stable river beds, and are coeval with fluvial terraces of rivers that flow perpendicular to the strike of bedding in gypsum monoclines. When rivers entrench,...

In the framework of a PhD thesis at the University of Bologna and the University of Savoie (France), and in collaboration with the University of Melbourne (Australia), an ambitious scientific project is being carried out with the aim of finding palaeoclimatic records in speleothems sampled in caves of Italy and the Dinaric Karst. In this first samp...

Most caves in Emilia-Romagna are developed in Triassic and Messinian gypsum outcrops. These evaporite rocks, although representing only around 1% of the surface outcrops, host over 600 caves, among which the longest epigenic cave in the world (the system Spipola-Acquafredda close to Bologna, with over 11 km of surveyed passages) and the deepest one...

A project of dating speleothems from the Piani Eterni Karst Complex started in 2013 thanks to a collaboration between the University of Bologna (Dept. Biological, Geological and Environ. Sciences), the National Park of the Dolomiti Bellunesi, the Central Commission for Speleology CAI, and the Venetian Speleological Federation. To date, several stal...

Some aspects of the climate of the last Interglacial (LIG) still appear poorly understood, such as the short-scale Rainfall vs Temperature variability. The North Atlantic Oscillation (NAO) is the main atmospheric pressure system controlling the intensity and direction of westerly winds, and distribution of moisture and heat across the Mediterranean...