Northeast Pacific Upper Cretaceous and Paleocene Glycymeridid Bivalves

Abstract

The Late Cretaceous to late Paleocene record of glycymeridid bivalves in the region extending from the Alaska Peninsula, southward to Baja California, Mexico is studied in detail for the first time. Glycymeris pacifica (Anderson, 1902), of late Cenomanian to late Turonian age, is the earliest known glycymeridid in the study area. Very locally, it is found with the middle to late Turonian Glycymeris yoloensis n. sp. The latter apparently represents some intermediate state between genus Glycymeris da Costa, 1778 and genus Glycymerita Finlay and Marwick, 1937. In the study area, Glycymerita is represented by Glycymerita veatchii (Gabb, 1864), middle to late Turonian to late Campanian; Glycymerita banosensis (Anderson, 1958) new combination, late Campanian to latest Maastrichtian; Glycymerita aleuta n. sp., known only from Alaska and of early Maastrichtian age; and Glycymerita major (Stanton, 1896) new combination, Selandian to Thanetian. All the studied species lived in warm-temperate, shallow-marine waters and were shallow burrowers in fine-grained siliciclastic sediments. Variability in morphology is common in sizeable populations of the various species, especially Glycymerita veatchii, which increased nearly fivefold in size during its 19.5 million-year-long range and culminated in shells up to 84 mm in length.

Biogenic carbonate mercury and marine temperature records reveal global influence of Late Cretaceous Deccan Traps

“…The Argentina 42 , Egypt 43,44,45 , Libya, and India 44 sample regions range from middle to latest Maastrichtian and were selected as possible records for direct comparison to Seymour Island and Moscow Landing, Alabama 27 . The samples from Washington 46 and Sweden 47,48 are known to be of earliest Maastrichtian age from biostratigraphic constraints 46–49 and were intended to serve as controls with respect to measured [Hg], because the host deposits predate eruptive windows of the Deccan Traps, and thus the samples were expected to have [Hg] values near background. The latitudinal range of sample localities spans from 70°N (Ocean Point, Alaska; 83–85°N paleolatitude) to 64°S (Seymour Island, Antarctica; 67°S paleolatitude), please see Supplementary Table 1 for detailed information.…”

Deep-water Tectono-Stratigraphy at a Plate Boundary Constrained by Large N-Detrital Zircon and Micropaleontological Approaches: Peninsular Ranges Forearc, Baja California, Mexico

“…Within the Punta Baja Formation, Kilmer (1963) recorded the ammonite Metaplacenticeras pacificum, suggesting that a middle Campanian age (Schile, 1974), however, an Early Campanian age was determined by Boehlke & Abbott (1986) based upon the presence of calcareous nannofossils (Phanulithus ovalis, a now outdated synonym of Calculites ovalis). 'Giant' specimens of the bivalve Glycymerita veatchii, transported within gravity flows, are found in pebbly sandstones of the Punta Baja Formation (Squires, 2010); these are considered to range in age from the late middle Campanian to late Campanian which coincides with the lower half of the Metaplacenticeras pacificum ammonite biozone (Squires, 2010).…”

“…The upper middle Campanian age given by Glycymerita veatchii bivalves in the Punta Baja Fm. (Squires, 2010) is based on their general increase in size from the Turonian onwards, so their large size in the Punta Baja Fm. may be related to localized environmental factors.…”

Vesiculation in the dinoflagellate cyst Cannosphaeropsis franciscana Damassa, 1979 across the K/Pg boundary (Vancouver Island, Canada) with implications for spiniferate gonyaulacacean taxonomy and ecophenotypy

“…The successful application of palynological assemblages for large-scale paleoenvironmental reconstructions requires a basis for accurate regional correlations with other well-studied areas of the world. To date, the biostratigraphic framework for the Cretaceous of the northeastern Pacific region is based largely on range data derived from macrofossil groups such as ammonites (Usher, 1952;Matsumoto, 1960;Jones, 1963;Jeletzky, 1964;Imlay and Jones, 1970;Muller and Jeletzky, 1970;Ward, 1978aWard, , 1978bHaggart et al, 2005Haggart et al, , 2009Haggart et al, , 2011Ward et al, 2012;McLachlan and Haggart, 2018), bivalves (Imlay, 1959(Imlay, , 1961Jones, 1960;Jeletzky, 1965;Squires and Saul, 2006;Grey et al, 2008;Squires, 2010a) and gastropods (Squires and Saul, 2006;Squires, 2010b), with crinoids only recently used (Haggart and Graham, 2018). Studies of 2 marine microfossils have also been focused exclusively on foraminiferal (e.g., McGugan, 1964;Sliter, 1973;Dalby et al, 2009) and radiolarian (e.g., Pessagno Jr., 1977;Haggart and Carter, 1993;Carter and Haggart, 2006;Haggart et al, 2009) assemblages in the region.…”