The Canary record of the evolution of the North Atlantic Pliocene: New 40Ar/39Ar ages and some notable palaeontological evidence

Abstract

Two new 40 Ar/ 39 Ar ages (*) and previously published K/Ar ages of basaltic pillow lava flows are coeval with closely-related fossiliferous marine layers, allowing us to establish the beginning (5.8; 5.0; 4.8 Ma at Ajuí, Fuerteventura Island and 4.8 ± 0.03 Ma (2)* at Tamaraceite) and a middle stage (4.20 ± 0.18 Ma (2)* at La Esfinge in Gran Canaria Island) of Early Pliocene marine deposits in the Canary A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 2 Islands. Here the presence of tropicopolitan fossils (Megaselachus megalodon, Janthina typica) suggest the influence of a possible Central American Circumtropical Current during the Pliocene and in the North Atlantic basin. The presence of both Janthina typica and the Argonauta argo also indicate the occurrence of tropical storms in the area of the Canary Islands around that time. In addition, the pillow lava flow at La Esfinge overlies a submarine pyroclastic layer containing Ostrea offreti that was preserved in its life position, a fossil from the terminal Miocene and commonly found on the south eastern Iberian Peninsula. At La Cruz on Fuerteventura Island, a dune formed above marine deposits lies beneath a palaeosol and a basaltic lava flow that is was K/Ar dated at 2.9 Ma. Near El Mármol in Gran Canaria the corresponding palaeosol lies between lava flows K/Ar dated at 3 Ma. Based on these observations, we argue in this paper that the first appearance of the Canary Current, the eastern boundary current of the North Atlantic sub-tropical gyre, occurred between 4.2Ma and 2.9 Ma ago. This was followed by a major sea level drop (of about 40 m) and the formation of a first fossil-bearing palaeosol which indicate that major climate change that took place around 2.95-2.82 Ma.

Pliocene and Late Pleistocene actinopterygian fishes from Santa Maria Island, Azores (NE Atlantic Ocean): palaeoecological and palaeobiogeographical implications

“…macrogastropod, one neustonic gastropod and four holoplanktonic gastropods; Janssen et al 2008;Ávila et al 2015cBeu, 2017), four echinoderms (Madeira et al 2011), one brachiopod (Kroh et al 2008), one barnacle (Winkelmann et al 2010) and five sharks (Ávila et al 2012). This pattern of extinctions/extirpations from volcanic oceanic islands during late Pliocene time is also reported for other Atlantic archipelagos, such as Madeira (Santos et al 2012), the Canary Islands (Meco et al 2007(Meco et al , 2015(Meco et al , 2016Martín-González et al 2012;Baarli et al 2017) and Cabo Verde (Baarli et al 2017). Between 5.3 and 4.13 Ma, the protoisland of Santa Maria was probably entirely destroyed, originating a large seamount where marine sediments rich in organic debris were deposited (Ávila et al 2012;Ramalho et al 2017).…”

“…Fossil bony fishes are known from the island, but the last account for Santa Maria fossil Actinopterygii fishes dates from the 1950s and 1960s (Ferreira, 1955;Zbyszewski & Ferreira, 1962). With few exceptions (Ávila et al 2012;Betancort et al 2016), the majority of the published palaeoecological and palaeobiogeographical studies on the marine fauna and flora of the Macaronesian archipelagos targeted sessile or low-motility species, such as the marine molluscs, echinoderms, bryozoans, barnacles, ostracods and algae (Meco, 1977;Meco et al 1997Meco et al , 2015Meco et al , 2016Ávila et al 2008a, b, 2009a, b, 2015bWinkelmann et al 2010;Madeira et al 2011;Santos et al 2011Santos et al , 2012aMeireles et al 2012Meireles et al , 2014Ávila, 2013;Baarli et al 2013Baarli et al , 2017Betancort et al 2014;Johnson et al 2014;Rebelo et al 2014;Tuya et al 2017). Still largely unresolved, an interesting question is how the evolutionary patterns and processes inferred from these studies relate to the dispersal capabilities of species (Ávila et al 2019).…”

Paleogeotherms of a Midcrustal to Upper‐Crustal Profile Across the Northern North China Block: Implications for the Thermal Structure of Continental Arcs

“…Zircon U‐Pb dating and trace element analyses were conducted synchronously by laser ablation inductively coupled plasma mass spectrometry at the Wuhan Sample Solution Analytical Technology Company Limited located in Wuhan, Hubei Province in southeastern China following methods described in Liu et al (). 40 Ar/ 39 Ar incremental heating experiments on hornblende and biotite were obtained using an ARGUS‐VI mass spectrometer in the Argon Geochronology Laboratory at Oregon State University, USA, following methods described in Koppers et al () and Meco et al (). Detailed operating conditions for U‐Pb and 40 Ar/ 39 Ar laboratory procedures and data reduction are listed in Text S1 in the supporting information.…”

The antiquity of the Sahara Desert: New evidence from the mineralogy and geochemistry of Pliocene paleosols on the Canary Islands, Spain

“…In contrast, minerals that are common in long-rangetransported dust are typically derived from upper continental crustal rocks, and include quartz, mica, plagioclase, and K-feldspar, as well as carbonate minerals and phyllosilicate clay minerals (e.g., Glaccum and Prospero, 1980;Muhs, 2013). Thus, on volcanic islands such as the Canaries, the presence of upper-crust-derived minerals in soils, Balcells et al (1991) and Meco et al (2015) and location of Agua Tres Piedras study area. Also shown are the approximate areas of the three shield volcano complexes that make up the island (from Ancochea et al, 1996 andTroll, 2016, their Fig.…”