Palaeoclimatic reconstruction for the Late Oligocene La Val fossil site (Estadilla, Huesca, Spain) based on CLAMP and LMA

Abstract

In this paper, we reconstruct palaeoclimate for the late Oligocene (Chattian) La Val plant assemblage of Spain (NE Iberian Peninsula). Our study employs both CLAMP (Climate Leaf Analysis Multivariate Program) and LMA (Leaf Margin Analysis), the first time these two techniques have been directly compared, and is based on 25 morphotypes (representing 23 taxa) of woody dicot leaves from a single stratigraphic unit (layer LV6). Both methods have provided a similar result. Although the standard deviation of LMA is higher than CLAMP, the results of LMA are coherent with CLAMP. The palaeoclimatic variables obtained from CLAMP shows a marked contrast between WMMT and CMMT and between 3-WET (836.3 ± 145.4 mm) and 3-DRY (113 ± 33 mm). Meanwhile, the GROWSEAS (9.30 ± 0.7 months) points out that the growth season lasted almost all the year. These variations signal a seasonal contrast, showing the existence of a dry season. Results indicate a warm temperate climate with hot and dry summers. The palaeoclimatic variables obtained using CLAMP are: MAT 17.2 ± 1.7 °C, WMMT 25.5 ± 1.3 °C, CMMT 10 ± 1.8 °C and GSP 1480 ± 204 mm. The palaeoclimatic variables obtained using LMA are MAT 17.11 ± 4.61 °C (regression equation for data from East Asia) and 16.8 ± 4.7 °C (regression equation for data from Europe). The palaeoclimatic values estimated from La Val site match those obtained from other Oligocene sites from Iberia (e.g. As Pontes site) that rely on different palaeoclimate methods. These palaeoclimatic values obtained from La Val are also similar to those from several Oligocene localities (e.g. the Rot flora) in Europe and reflect peak temperature corresponding to the late Oligocene warming episode.