The reconstruction of Early and Middle Miocene climate and vegetation in Southern Germany as determined from the fossil wood flora

Early and Middle Miocene sediments of the North Alpine Foreland Basin (NAFB) in Southern Germany contain one of the worldʹs richest regional records of silicified wood. Here we analyze over 1000 identifiable samples, belonging to 80 wood-anatomical taxa from 61 stratigraphically well-dated localities using principally the Coexistence Approach. The samples investigated originate from fluvial sediments representing periods of intensified surface runoff in the NAFB and therefore represent and provide information pertaining to the wet end-member of the fluctuating climate system. The dry end of the climate system is represented in the profiles either by hiatuses or palaeosoils. taset is split into four xylofloras: (I) the Ortenburg xyloflora (Late Ottnangian; ∼ 17.5 to 17.3 Ma) originating from a paratropical evergreen Carapoxylon (Xylocarpus) forest; (II) the Southern Franconian Alb xyloflora (Late Karpatian; 17.0 to ∼ 16.3 Ma) originating from a subtropical semi-deciduous limestone forest; (III) the upper Older Series xyloflora (Early Badenian; ∼ 16.3 to ∼ 15.3 Ma) originating from a subtropical oak–laurel forest; and (IV) the upper Middle Series xyloflora (Middle Badenian; 14.3 to ∼ 13.8 Ma) originating from a subtropical dry deciduous forest. vestigation documents the following important outcomes: (1) the Late Ottnangian seems to be the warmest period during the investigated time span, with a mean annual temperature (MAT) between 22.2 and 24.2 °C and a cold month temperature (CMT) around 16.7 °C. The Late Ottnangian is significantly warmer by at least 1.7 °C MAT and up to 3.4 °C CMT than the Mid-Miocene Climatic Optimum (i.e. MAT 17.4–20.5 °C and CMT 8.0–13.3 °C of the Late Karpatian to Middle Badenian, ∼ 17 to ∼ 13.8 My) and may correspond to the First Climatic Optimum (17.7–16.7 Ma) of the southern oceans [Pekar, S.F., Marchitto, T., Lynch-Steiglitz, J., 2002. Evidence for Water-Mass Changes on the Tasmanian Slope during the Early Miocene (19–16.5 Ma): Stable Isotope and Mg/Ca Records from ODP Leg 189 Site 1168. Eos, Transactions, American Geophysical Union 83(47), Fall Meet. Supplement, Abstract PP11C-06, F 926-927.]. (2) The cooling between both climate optima is documented by the Southern Franconian Alb xyloflora and probably reflects the Mi2 build-up phase of the Antarctic ice-sheets. (3) From Late Ottnangian to Middle Badenian the wet end-member of the climate system appears to be humid (Mean Annual Precipitation ∼ 830–∼ 1.350 mm) and with relatively even distribution of rainfall throughout the year. Only the Late Karpatian is characterized by the occurrence of a distinct dry season probably occurring during the early spring or late autumn. (4) We attributed the Early to Middle Badenian vegetation change to an increase in intra-basin relief, rather than to a different climate.