Papers by Giovanni Zanchetta
This study presents the first cosmogenic 36 Cl surface exposure data from a moraine in the Former... more This study presents the first cosmogenic 36 Cl surface exposure data from a moraine in the Former Yugoslav Republic of Macedonia (FYROM). Five limestone boulders from an end moraine in the Galicica Mountains (40.94 N, 20.83 E, 2050 m a.s.l.) were used for cosmogenic 36 Cl surface exposure dating. The 36 Cl concentrations from the five boulders are identical within their measurement uncertainties ruling out major effects of inheritance, erosion, or snow cover. The calculated ages are very consistent ranging from 11.3 ± 1.3 to 12.8 ± 1.4 ka (mean 12 ± 0.6 ka) after applying a Ca-spallation production rate of 56 at g À1 a À1 (LSD scaling) and correction for 5 mm ka À1 carbonate weathering and 2% snow shielding. The applied corrections for weathering and snow shielding cause a shift to older ages in the order of magnitude of ca. 5% on average, making the production rate the main impact on exposure ages. The ages point to a moraine formation during the Younger Dryas period, consistent with the timing of the last deglaciation in the Galicica Mountains derived from previous geomorphological studies in the area. The formation of a glacier was likely favoured by several topoclimatic factors, accounting for additional snow input. This interpretation is in line with regional studies on glaciation chronologies from Sara Range (FYROM/Republic of Kosovo), Retezat Mountains (Romania), Mt. Chelmos (Greece), Mount Orjen (Montenegro) and Durmitor (Montenegro). Lake sediment analyses of Prespa (Republic of Albania/ FYROM/Greece), Maliq (Republic of Albania) and Dojran lakes (FYROM/Greece) indicate that cold conditions promoted the formation of a local cirque glacier. However, studies of sediment records of the adjacent lakes Ohrid (Republic of Albania/FYROM) and Prespa do not indicate the presence of a proximal glaciation. An explanation might be a combination of the small size of the cirque glacier, generating only small amounts of debris, and the karstic bedrock, which hampers fluvial transport and acts by its aquifer system as a natural sediment trap, as the fluvial transport of the sediments to the lakes is absorbed by the karst system.
Earth has experienced seven glacial-interglacial cycles over the last~ 700 kyr. The glacial perio... more Earth has experienced seven glacial-interglacial cycles over the last~ 700 kyr. The glacial periods are generally brought to an abrupt end during so-called 'terminations'. Milankovitch Theory suggests that variations in summer insolation at high northern latitudes drive the glacial-interglacial cycles, and trigger the onset of terminations. To test this hypothesis, it is necessary to firmly establish the precise timing of glacial terminations in both hemispheres and compare this with variations in Northern Hemisphere summer insolation. In spite of an ...
Geophysical Research Abstracts, Apr 13, 2008
Speleothems from Corchia Cave, Italy provide long and detailed records of North Atlantic paleocli... more Speleothems from Corchia Cave, Italy provide long and detailed records of North Atlantic paleoclimate with clear correlations to polar ice core data. U-Th, U-Pb and UU dating reveals overlapping growth periods from the Holocene to over 1 Ma. Mass spectrometric U-Th dating works well for Corchia speleothems younger than about 400 ka, giving uncertainties of 1 ka for MIS 5, 3 ka for MIS 7 and 10 ka for MIS 9. Corchia stalagmites are particularly suitable for U-Pb dating, allowing its routine use on samples younger than ...
EGU General Assembly 2009, held 19-24 April, 2009 in Vienna, Austria http://meetings. copernicus. org/egu2009, p. 10192, Apr 1, 2009
Antro del Corchia is a large, well-decorated cave located in the Alpi Apuane of northwestern Tusc... more Antro del Corchia is a large, well-decorated cave located in the Alpi Apuane of northwestern Tuscany, Italy. Previous studies from the cave covering the period between Termination II and the early last glacial show that speleothem oxygen isotope ratios (^ 18O) closely track sea-surface temperature (SST) variations recorded in marine sediments cored off the Iberian margin (cores ODP-977A, MD95-2042 and MD01-2444). This allows the U-series-based Corchia speleothem chronology to be applied to the Iberian marine record, ...
Lake Ohrid is probably of Pliocene age, and the oldest extant lake in Europe. In this study clima... more Lake Ohrid is probably of Pliocene age, and the oldest extant lake in Europe. In this study climatic and environmental changes during the last glacial-interglacial cycle are reconstructed using lithological, sedimentological, geochemical and physical Electronic supplementary material The online version of this article (
Volcanic ash produced during explosive eruptions can have very severe impacts on modern technolog... more Volcanic ash produced during explosive eruptions can have very severe impacts on modern technological societies. Here, we use reconstructed patterns of fine ash dispersal recorded in terrestrial and marine geological archives to assess volcanic ash hazards. The ash-dispersal maps from nine Holocene explosive eruptions of Italian volcanoes have been used to construct frequency maps of distal ash deposition over a wide area, which encompasses central and southern Italy, the Adriatic and Tyrrhenian seas and the Balkans. The maps are presented as two cumulative-thickness isopach maps, one for nine eruptions from different volcanoes and one for six eruptions from Somma-Vesuvius. These maps represent the first use of distal ash layers to construct volcanic hazard maps, and the proposed methodology is easily applicable to other volcanic areas worldwide.
Earth and Planetary Science Letters, 2004
The age structure and stable isotope composition of a stalagmite (CC1) from an upland cave in cen... more The age structure and stable isotope composition of a stalagmite (CC1) from an upland cave in central-western Italy were studied to investigate regional response to global climatic changes. Four growth phases are constrained by 28 thermal ionization and multi-collector inductively coupled plasma mass spectrometry Th-U ages and reveal intermittent deposition through the period between Marine Isotope Stage (MIS) 11 and 3 (~380 and~43 kyr). Most of the growth took place between~380 and~280 kyr, a period punctuated briefly by a hiatus in deposition through the glacial maximum of MIS 10. Growth was terminated abruptly at 280 kyr just prior to the MIS 8 glacial maximum. With a present-day chamber temperature of 7.5 8C, the timing of hiatuses close to these glacial maxima point to freezing conditions at the time. No deposition was recorded through the entirety of MIS 7 and most of MIS 6, whilst two minor growth phases occurred at~141-125 and~43 kyr. Growth at 141 kyr indicates temperatures N0 8C at a time when MIS 6 ice volumes were close to their maximum. High stable carbon isotope (y 13 C) values (À2.8x to +3.1x) throughout the stalagmite's growth reflect a persistently low input of biogenic CO 2 , indicating that the steep, barren and alpine-like recharge area of today has been in existence for at least the last~380 kyr. During MIS 9, the lowest y 13 C values occur well after maximum interglacial conditions, suggesting a lag in the development of post-glacial soils in this high-altitude karst. The stable oxygen isotope (y 18 O) trends match the main structural features of the major climate proxy records (SPECMAP, Vostok and Devils Hole), suggesting that the y 18 O of CC1 has responded to global-scale climate changes, whilst remarkable 0012-821X/$ -see front matter D similarity exists between CC1 y 18 O and regional sea-surface temperature reconstructions from North Atlantic core ODP980 and southwest Pacific marine core MD97-2120 through the most detailed part of the CC1 record, MIS 9-8. The results suggest that CC1 and other stalagmites from the cave have the potential to capture a long record of regional temperature trends, particularly in regards to the relative severity of Pleistocene glacial stages. D
Earth and Planetary Science Letters, 2004
Supplementi di Geografia Fisica e Dinamica Quaternaria
The triggering of destructive volcaniclastic flows is a one of the most recurrent and dangerous n... more The triggering of destructive volcaniclastic flows is a one of the most recurrent and dangerous natural phenomena that can occur in volcanic areas. They can originate not only during or shortly after an eruption (syn-eruptive) but also during a volcanic quiescence (inter-eruptive), when heavy rains remobilize the loose pyroclastic deposits. One of most important example of inter-eruptive volcaniclastic flow hazard
A 23-cm long core has been extracted from a subaqueous calcite mound growing on the floor of a po... more A 23-cm long core has been extracted from a subaqueous calcite mound growing on the floor of a pool in Corchia Cave (Italy). A low-resolution (1 mm-increment) stable isotope record from this core, coupled with six preliminary 234U/230Th and 234U/238U ages, suggests a continuous, or near-continuous, record of glacial-interglacial cycles extending back to~ 1 Ma. Here we present preliminary data on the petrographic, trace element and organic fluorescence composition of the calcite, which can be used to help support the ...
The volcaniclastic flows are among the most recurrent and dangerous natural hazards in volcanic t... more The volcaniclastic flows are among the most recurrent and dangerous natural hazards in volcanic terrains characterized by recurrent pyroclastic deposition. Their recurrence usually increases during and shortly after an eruptive event but they can also be generated by storms or earthquakes during volcanic quiescence. Damage and casualties relate to these events are common in the history of recent (AD 1631–1944) activity of Vesuvius, both near the volcanic complex and in the sub-Apennine basins affected by pyroclastic fallout. An example is the catastrophic event occurred on 5 and 6 May 1998 in the area of Sarno (Southern Italy), which highlights the destructive potential of debris flows, even when they are of relatively low magnitude. More than 130 people were killed and severe property damage took place when volcaniclastic debris flows triggered by heavy rainfall inundated various towns located in piedmont areas. With the aim to mitigate and prevent the volcaniclastic flow hazard, s...
Continuous, well-dated palaeoclimate records extending beyond the limits of uranium-thorium datin... more Continuous, well-dated palaeoclimate records extending beyond the limits of uranium-thorium dating (~500 ka) are now possible from speleothems following recent advances in uranium-lead (U-Pb) dating. Corchia Cave (NW Italy) contains some of the cleanest, high-uranium-concentration speleothems available (2-25 ppm), making them ideal for U-Pb dating. The speleothems grow in a region that lies in the path of mid-latitude westerlies crossing from the North Atlantic. Late Pleistocene speleothems from the cave show that stable isotope variations respond to changes in sea-surface temperatures, which are strongly controlled by the strength of meridional overturning circulation. We present new multi-proxy data from several Corchia Cave speleothems which grew during the last 1 Ma. The longest and potentially most complete record is preserved in a 23-cm core recovered from an actively forming subaqueous calcite mound growing from the floor of a cave pool. Stable oxygen and carbon isotope ratio...
Journal of Quaternary Science, 1996
Eclogae Geologicae Helvetiae
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Papers by Giovanni Zanchetta