Tudor Tămaş

Mineralogical data on bat guano deposits from three Romanian caves

Mineralogical studies performed on crusts, nodules and earthy masses from the Romanian caves Gaura cu Muscă, Gaura Haiducească and Peștera Zidită have revealed the presence of three different phosphate associations. The minerals have been identified by means of X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. Five phosphates have been identified in the samples, with hydroxylapatite the only common mineral in all the three caves. Brushite, taranakite, leucophosphite and variscite are the other phosphates identified. Associated minerals include gypsum, calcite, quartz, and illite-group minerals. Aside from differences in the lithology, the occurrences of the different phosphate minerals indicate variable pH and relative humidity conditions near or within the guano accumulations.

Somes Plateau: Măgurici Cave (Pestera de la Măgurici de la Răstoci)

Măgurici Cave in the Somes Plateau of NW Romania hosts a large deposit of bat guano. Pollen and stable isotope investigations on this cave material provide meaningful information regarding the paleoclimate and paleoenvironmental conditions over the past 1200 years. Apart for some gypsum crystals, the cave is deprived of spectacular speleothems, but it contains nodules, crusts, and earthy masses in whose composition eight phosphate and four sulfate minerals were identified.

A guano-derived δ13C and δ15N record of climate since the Medieval Warm Period in north-west Romania: A GUANO-DERIVED δ13C AND δ15N RECORD

A 285‐cm core of bat guano was recovered from Măgurici Cave in north‐west Romania and analyzed for δ13C, δ15N and pollen. Guano deposition occurred from AD 881 until 1240 and from AD 1651 to 2013, allowing for the interpretation of summer variations in precipitation and temperature during the Medieval Warm Period (MWP) and the Little Ice Age (LIA). A 2‰ increase in δ13C, 1.5‰ decrease in δ15N, and the presence of Ulmus, Quercus and Carpinus betulus indicate a warm and dry MWP occurred in the region. The lack of deposition during the beginning of the LIA suggests a possible climate‐induced change in prey availability resulting in bats vacating the cave. Variation of δ13C values between −25 and −23‰ at AD 1650 (LIA) indicates similar drier conditions as at the end of MWP. However, a 2‰ decrease in δ13C values that occurred between AD 1790 and 1900 suggests climate was trending towards wetter conditions at the end of the LIA. From AD 1938 to 2013, δ13C values appear to be more influenced by temperature, indicating that this parameter had a more significant effect on carbon discrimination than water availability.