Franceschi M.,University of Padua |
Penasa L.,University of Padua |
Coccioni R.,Urbino University |
Gattacceca J.,Jerome Gattacceca |
And 4 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2015
Terrestrial laser scanner imaging is applied, together with calcimetry and lithofacies logging, for the cyclostratigraphic characterization of the Ypresian-Lutetian pelagites exposed in the Smirra section (Umbria-Marche Basin, Italy). The necessary chronostratigraphic framework is provided by detailed bio- and magnetostratigraphic analyses, which allow locating the Ypresian-Lutetian boundary in this section. Terrestrial laser scanner intensity is compared to carbonate content values obtained through calcimetric analyses carried out on samples taken from the same section, and is found to represent a good proxy for lithology in these pelagic homogenites. Time-series analysis highlights Milankovitch frequencies, particularly evident in the high-resolution terrestrial laser scanner intensity series. The recognition of distinctive low-frequency (>. 1. Myr) features in the amplitude oscillations of short eccentricity as well as its ~. 400. kyr modulation (long eccentricity), promote a tuning of the Smirra series using the most recent astronomic solution (La2010 nominal), which provides insights on the ages of the Y-L boundary and of the main biostratigraphic and magnetostratigraphic events in the Umbria-Marche Basin. Results confirm the value of high-resolution (mm-scale) terrestrial laser scanning for scrutinizing pelagite successions in search of low-frequency cycles that may help in the refinement of the astrochronological time scale. © 2015 Elsevier B.V.
Peterson D.E.,University of California at Berkeley |
Finger K.L.,University of California at Berkeley |
Iepure S.,Speleological Institute Emil Racovitza |
Mariani S.,Gruppo Speleologico CAI Fabriano |
And 2 more authors.
Journal of Cave and Karst Studies | Year: 2013
Rich, diverse assemblages comprising a total (live + dead) of twenty-one ostracod species belonging to fifteen genera were recovered from phreatic waters of the hypogenic Frasassi Cave system and the adjacent Frasassi sulfidic spring and Sentino River in the Marche region of the northeastern Apennines of Italy. Specimens were recovered from ten sites, eight of which were in the phreatic waters of the cave system and sampled at different times of the year over a period of five years. Approximately 6900 specimens were recovered, the vast majority of which were disarticulated valves; live ostracods were also collected. The most abundant species in the sulfidic spring and Sentino River were Prionocypris zenkeri, Herpetocypris chevreuxi, and Cypridopsis vidua, while the phreatic waters of the cave system were dominated by two putatively new stygobitic species of Mixtacandona and Pseudolimnocythere and a species that was also abundant in the sulfidic spring, Fabaeformiscandona ex gr. F. fabaeformis. Pseudocandona ex gr. P. eremita, likely another new stygobitic species, is recorded for the first time in Italy. The relatively high diversity of the ostracod assemblages at Frasassi could be attributed to the heterogeneity of groundwater and associated habitats or to niche partitioning promoted by the creation of a chemoautotrophic ecosystem based on sulfur-oxidizing bacteria. Other possible factors are the geologic age and hydrologic conditions of the cave and karst aquifer system that possibly originated in the earlymiddle Pleistocene when topographic uplift and incision enabled deep sulfidic waters to reach the local carbonate aquifer. Flooding or active migration would have introduced the invertebrates that now inhabit the Frasassi Cave system.