A multi-proxy geochemical investigation of the early Paleocene (Danian) continental palaeoclimate at the Fontllonga-3 site (South Central Pyrenees, Spain)

Abstract

Chronologically well constrained non-marine deposits across the Cretaceous-Tertiary boundary (KTb) are exceptionally rare. The Fontllonga section (Tremp Formation, South Central Pyrenees, Lleida, Spain) constitutes one of these rare global records. Stable isotope (δ 18 O CO3 and δ 13 C) analyses have been performed on the carbonate fraction of 29 samples from diverse skeletal micro-remains (charophyte gyrogonites, gastropod shells, ostracod valves and isolated skeletal remains of lepisosteids and pycnodonts) from the earliest Danian site, Fontllonga-3. A mean Ba/Ca water palaeotemperature of 28.0 ± 6.7°C has been obtained from the ganoine of 25 lepisosteid scales. This mean palaeotemperature is comparable with the temperature tolerance range for extant relatives of fossil osteoglossiform fish found at Fontllonga-3, which require a temperature range of 24°-35°C (mean annual temperature 27-30°C) to survive. Using the temperature range provided by the Ba/Ca palaeothermometer (21.3-34.7°C), it is possible to determine δ 18 O water values from the isotopic content of charophyte gyrogonites, gastropod shells, ostracod valves and fish remains (mean δ 18 O CO3 = − 5.00 ‰, σ = 0.21). δ 18 O water values of between − 4.01 and −0.95‰ (VSMOW) are calculated, which, when combined with (La/Yb) N versus (La/Sm) N plots, are in good agreement with the sedimentary interpretation of the site as an estuarine environment. Based upon a comparison with modern day meteorical conditions these isotopic values are relatively high for subtropical freshwaters, suggesting a low precipitation rate (amount effect, high evaporation rate and/or long residence time). When combined with other isotopic, palaeobotanical and mineralogical studies carried out in the Pyrenean and Tethys realms this first geochemical study of an early Paleocene site is consistent with there being a subtropical seasonally dry climate in the South Central Pyrenees at this time.

Weathering evolution in lutites of the K/Pg transition red beds of the Tremp Group (Tremp-Isona Basin, south Pyrenees)

“…The early Paleocene near the top of the Lower Red Unit in the central Pyrenees is represented by a lenticular clay bed at the top of a thickening-upward sequence of channelled sandstones, showing lateral accretion and sigmoidal stratification, interpreted as an upper estuary deposit (López-Martínez et al, 1998). The isotope data for this deposit (Fontllonga 3 site), combined with other isotopic, palaeobotanical and mineralogical studies carried out in the Pyrenean and Tethys realms, are consistent with a subtropical, seasonally dry climate in the south-central Pyrenees at this time (Domingo et al, 2007).…”

“…The sampled sections in Red Units include lutites of alluvial and flood plain deposits with frequent calcite nodules (samples of L = 6 in Table 1 (deposited at: http://www.minersoc.org/pages/e_journals/dep_mat_ cm.html)), palaeosoils (samples G45 and G46 of L = 6 in Table 1), sheet-floods and reworked lutites. Thus, in the sedimentary basin there is an important contribution by clay-minerals formation to climatic conditions, similar to those established for the above-mentioned source areas, known mainly through 18 O and 13 C isotopic data from soil carbonate nodules (López-Martínez et al, 1998;Schmizt & Pujalte, 2003;Domingo et al, 2007;Riera et al, 2013).…”

Compositional changes in fish scale hydroxylapatite during early diagenesis; an example from an abandoned meander

“…Our observations thus throw serious doubts on the potential of chemical analyses of bones to provide information on paleoenvironmental conditions and paleodietary paterns, which is an approach long questioned but still often applied (Trueman and Tuross 2002;Martínez-García et al 2005;Zapata et al 2006). They also call in question the use of Sr and Ba as paleothermometers (Balter and Lécuyer 2004;Domingo et al 2007).…”

Preservation of successive diagenetic stages in Middle Triassic bonebeds: Evidence from in situ trace element and strontium isotope analysis of vertebrate fossils

“…Thus, REE patterns have frequently been used to study various aspects of the fossilisation environment such as reconstruction of the palaeoenvironment, taphonomy, palaeoceanography, provenance and reworking of vertebrate remains (e.g., Wright et al, 1984Wright et al, , 1987Elderfield and Pagett, 1986;Denys et al, 1996;Girard and Albarède, 1996;Samoilov et al, 2001;Picard et al, 2002;Kemp and Trueman, 2003;Trueman et al, 2003Trueman et al, , 2005Trueman et al, , 2006Lécuyer et al, 2003Lécuyer et al, , 2004Metzger et al, 2004;Martin et al, 2005;Labs-Hochstein and MacFadden, 2006;Ounis et al, 2008;Anderson et al, 2007;Domingo et al, 2007Domingo et al, , 2009aDomingo et al, , 2009bDomingo et al, , 2011Cook and Chemical Geology 410 (2015) 108-123 Grandstaff and Terry, 2009;Kocsis et al, 2009;Iliopoulos et al, 2010;Rogers et al, 2010;Suarez et al, 2010;Patrick, 2013aPatrick, , 2013bZhao et al, 2013).…”