Late Pleistocene Climate and Dust Source From the Mobarakabad Loess–Paleosol Sequence, Northern Foothills of the Alborz Mountains, Northern Iran

Paleoclimatic investigation of loess-paleosol sequences from northern Iran is important for understanding past changes in a region highly sensitive to shifts in precipitation, and along potential routes of past human migration. Here, we present carbon and oxygen isotopic compositions of bulk carbonate (δ13Cbc and δ18Obc, respectively) coupled with particle size distributions of samples from the Mobarakabad section, northern Iran, to study past wind dynamics and hydroclimate. We also present new initial clay-sized Hf-Nd isotope results from key horizons in order to assess general dust sources. Variations of δ13Cbc and δ18Obc values of modern soils compared to paleosols allow reconstruction of late Pleistocene–Holocene climate change in the area. Our results show severe drought during a major eolian deposition phase (EDP) after 34 ka. The thickness and PSD of the C horizon of unit 5 suggest significant shifts in loess sources and depositional environments during this EDP after 34 ka. Indeed, based on our new clay-sized Hf-Nd data, we hypothesize that the loess unit 5 might originate from the young crustal source of the Alborz and Kopet Dagh mountains. In general, the PSD of C horizons in the section is bimodal in the silt fraction and the very small, very fine clay fraction, with a mode at c. 1 μm in the modern soil and paleosols possibly produced by weathering and pedogenic processes. There also appears to be a good correlation between δ13Cbc and δ18Obc values, differentiating phases of loess accumulation and paleosol formation and hence providing quantitative data for reconstructing paleoclimatic conditions in the study area.

Contributions to the taxonomy and biogeography of the genus Dichagyris (subg. Dichagyris) Lederer, 1867 (Lepidoptera, Noctuidae, Noctuinae)

The taxonomically important characters and subgeneric subdivision of Dichagyris are presented with several historical and nomenclatural considerations. Subdivision of D. vallesiaca is revised based on the type material of the known subspecies. The D. psammochroa group is revised, with description of a new species, D. kurbatskyi from Kazakhstan, and one new subspecies, D. psammochroa kopetdaghimena from the Kopet-Dagh massif. The D. taftana group is revised, with the description of a new species (D. guentereberti from Afghanistan) and two new subspecies (D. taftana elborsasta and D. taftana safavida, from different areas of Iran). The eastern sister species of D. humilis, D. hypotacta from Afghanistan and Pakistan, is described. Major phylogenetic clades of Dichagyris s. str. are associated to western Palaearctic and/or Central Asiatic mountainous regions. Core areas of allopatric speciation of Dichagyris s. str. are discussed with taxonomic considerations and outlook on the subgenera Yigoga and Albocosta, as well.