Sequence stratigraphic framework of the mid-Cretaceous nonmarine Potomac Formation, New Jersey and Delaware

ABSTRACT We developed a sequence stratigraphic framework for the (Barremian to lower Cenomanian) fluvial–deltaic (primarily delta plain) Potomac Formation in the Medford, New Jersey, Fort Mott, New Jersey, and Summit Marina, Delaware coreholes. Previous studies have correlated distinctive lithologic units with attendant pollen zones and identified tentative sequence boundaries between lithologic units I (Barremian to lower Aptian, pollen Zone I), II (Aptian to lowermost Cenomanian, pollen Zone II), and III (lower Cenomanian, pollen Zone III) at all three sites. Here, we further subdivide these units into packages known as fluvial aggradation cycles (FACs). An analysis of FAC stacking patterns reveals potential sequence boundaries and systems tracts. FACs indicate that major lithologic unit boundaries are also sequence boundaries, indicate tentative higher-order sequence boundaries, and provide potential additional correlative surfaces among Potomac Formation sites. Our study demonstrates the applicability of the FAC method to identify stacking patterns and sequence stratigraphic surfaces in fluvial–deltaic deposits and demonstrates that FACs are excellent tools to decipher the difficult-to-correlate surfaces.

Middle Miocene climate of southwestern Anatolia from multiple botanical proxies

The middle Miocene climate transition (MMCT) was a phase of global cooling possibly linked to decreasing levels of atmospheric CO2. The MMCT coincided with the European Mammal Faunal Zone MN6. From this time, important biogeographic links between Anatolia and eastern Africa include the hominid Kenyapithecus. Vertebrate fossils suggested mixed open and forested landscapes under (sub)tropical seasonal climates for Anatolia. Here, we infer the palaeoclimate during the MMCT and the succeeding cooling phase for a middle Miocene (14.8–13.2 Ma) intramontane basin in southwestern Anatolia using three palaeobotanical proxies: (i) Köppen signatures based on the nearest living-relative principle; (ii) leaf physiognomy analysed with the Climate Leaf Analysis Multivariate Program (CLAMP); (iii) genus-level biogeographic affinities of fossil flora with modern regions. The three proxies reject tropical and hot subtropical climates for the MMCT of southwestern Anatolia and instead infer mild warm temperate C climates. Köppen signatures reject summer-dry Cs climates but cannot discriminate between fully humid Cf and winter-dry Cw; CLAMP reconstructs Cf climate based on the low X3.wet∕X3.dry ratio. Additionally, we assess whether the palaeobotanical record resolves transitions from the warm Miocene Climatic Optimum (MCO, 16.8–14.7 Ma) to the MMCT (14.7–13.9 Ma), and a more pronounced cooling at 13.9–13.8 Ma, as reconstructed from benthic stable isotope data. For southwestern Anatolia, we find that arboreal taxa predominate in MCO flora (MN5), whereas in MMCT flora (MN6) abundances of arboreal and non-arboreal elements strongly fluctuate, indicating higher structural complexity of the vegetation. Our data show a distinct pollen zone between MN6 and MN7+8 dominated by herbaceous taxa. The boundary between MN6 and MN7+8, roughly corresponding to a first abrupt cooling at 13.9–13.8 Ma, might be associated with this herb-rich pollen zone.

Middle Miocene climate of southwestern Anatolia from multiple botanical proxies

The middle Miocene climate transition (MMCT) was a phase of global cooling possibly linked to decreasing levels of atmospheric CO2. The MMCT coincided with the European Mammal Faunal Zone MN6. From this time, important biogeographic links between Anatolia and eastern Africa include the hominid Kenyapithecus. Vertebrate fossils suggested mixed open and forested landscapes under (sub)tropical seasonal climates for Anatolia. Here, we infer the palaeoclimate during the MMCT and the succeeding cooling phase for a middle Miocene (14.8–13.2 Ma) of an intramontane basin in southwestern Anatolia using three palaeobotanical proxies: (i) Köppen signatures based on the nearest-living-relative principle. (ii) Leaf physiognomy analysed with the Climate Leaf Analysis Multivariate Program (CLAMP). (iii) Genus-level biogeographic affinities of fossil floras with modern regions. The three proxies reject tropical climates for the MMCT of southwestern Anatolia and instead infer warm temperate C climates. Köppen signatures reject summer-dry Cs climates but cannot discriminate between fully humid Cf and winter-dry Cw; CLAMP reconstructs Cf climate based on the low X3.wet/X3.dry ratio. Additionally, we assess whether the palaeobotanical record does resolve transitions from the warm Miocene Climatic Optimum (MCO, 16.8–14.7 Ma) into the MMCT (14.7–13.9 Ma), and a more pronounced cooling at 13.9–13.8 Ma, as reconstructed from benthic stable isotope data. For southwestern Anatolia, we find that arboreal taxa predominate in MCO floras (MN5), whereas in MMCT floras (MN6) abundances of arboreal and non-arboreal elements strongly fluctuate indicating higher structural complexity of the vegetation. Our data show a distinct pollen zone between MN6 and MN7+8 dominated by herbaceous taxa. The boundary MN6 and MN7+8, roughly corresponding to a first abrupt cooling at 13.9–13.8 Ma, possibly might be associated with this herb-rich pollen zone.

Miocene palynoflora from the KRAM-P 218 leaf assemblage from the Bełchatów Lignite Mine (Central Poland)

During a palynological analysis of four samples from the Bełchatów KRAM-P 218 collection of plant macroremains 95 fossil species of sporomorphs were identified. Among the non-pollen palynomorphs was the fossil species Desmidiaceaesporites cosmarioformis, previously not reported from fossil floras of Poland, most probably related to the zygospores of desmids. The pollen analysis indicates the presence of a freshwater body (probably an oxbow lake) and shows the dominant role of wetland, predominantly riparian vegetation, at the time of sedimentation. The riparian forests probably consisted of Carya, Pterocarya, Celtis, and Ulmus, accompanied by Alnus, Acer, Fraxinus, Juglans, Liquidambar, Vitis, Zelkova, and Salix. In mixed forests there probably were Fagus, Quercus, Carpinus, Eucommia, Corylus, Tilioideae, and conifers, as well as some thermophilous taxa (e.g. Castanea, Symplocos, Reevesia, Mastixiaceae, and plants producing pollen of the fossil species Tricolporopollenites pseudocingulum). Taxodium, Nyssa, and presumably Glyptostrobus and Alnus were components of swamp communities that might have overgrown the adjacent area with higher groundwater. Members of the families Ericaceae, Cyrillaceae, and Clethraceae, as well as Myrica and probably also Ilex, may have been components of swamp forests and bush swamps. Our analysis indicates that the climate was warm temperate and moderately wet. The palynoflora is most similar in composition to the spore-pollen spectra of the X climatic phase - the Nyssapollenites spore-pollen zone. Deposits bearing assemblages of the Nyssapollenites spore-pollen zone were deposited during the Sarmatian and early Pannonian. Our results are consistent with those from plant macroremains from the same collection.

Inferences from geochemical characteristics of the upper part of the Middle Pleistocene interglacial deposits in Lithuania

The study presents geochemical characteristics of deposits from the reference sections of the Middle Pleistocene interglacials: 2 from the Butėnai Interglacial and 2 from the problematic Snaigupėlė Interglacial. Geochemical data (the contents of 29 chemical elements, percentages of sediment components) are related to magnetic susceptibility (MS), bedding, lithology and previous palaeobotanical results. Higher content of carbonates and clay in sections of the Snaigupėlė Interglacial can be explained by warmer climate and calmer depositional environment, though the influence of chemical composition of the provenance and underlying tills is also obvious. The influence of oxic-anoxic sedimentary environment fluctuations on MS and on the separation between P-Fe and S-Mn is demonstrated. Many geochemical differences between deposits from the intervals of the Snaigupėlė-705 borehole and the Snaigupėlė outcrop sections which presumably include pollen zone S6 Carpinus-Quercus enable to speculate that these deposits were formed during different interglacials.

Changes of Water Level in the Eemian Palaeolake at Imbramowice (SW Poland) Based on Isotopic and Cladoceran Data

Isotopic and cladoceran investigations of Eemian (MIS 5e) lake sediments from Imbramowice, SW Poland, allow us to reconstruct the environmental conditions, especially changes of water level and trophic status, during the early and middle Eemian Interglaciation. We analyzed the sediments from 6.5 to 11.0 m depth in a core provided by Mamakowa (1989). The upper 6.5 m had insufficient carbonates and cladoceran contents for analyses. The analyzed section consists of sandy and organic silts at the bottom, followed by gyttja characterized by increasing CaCO3 content. Measured δ18O values oscillate from ca. -9 to -4‰ and δ13C from -3.5 to above + 6‰. Based on stable isotope analyses of carbonates, we define and characterize eight isotopic horizons (Is). We identify 26 taxa of subfossil Cladocera and seven zones (CLZ) of faunal development. Probably the greatest depth of the lake occurred with pollen zone E2; shallowing then took place. During pollen zones E2-E3, gradual warming is observed and expressed through a positive trend in both δ18O and δ13C values. Pollen zone E4 is characterized by frequent changes of water level. During the Eemian Interglaciation, excluding the initial phase of lake evolution, the lake was meso-eutrophic and eutrophic with high phytoplankton productivity.

The Radiocarbon Chronology of El Mirón Cave (Cantabria, Spain): New Dates for the Initial Magdalenian Occupations

Three additional radiocarbon assays were run on samples from 3 levels lying below the classic (±15,500 BP) Lower Cantabrian Magdalenian horizon in the outer vestibule excavation area of El Mirón Cave in the Cantabrian Cordillera of northern Spain. Although the central tendencies of the new dates are out of stratigraphic order, they are consonant with the post-Solutrean, Initial Magdalenian period both in El Mirón and in the Cantabrian region, indicating a technological transition in preferred weaponry from foliate and shouldered points to microliths and antler sagaies between about 17,000–16,000 BP (uncalibrated), during the early part of the Oldest Dryas pollen zone. Now with 65 14C dates, El Mirón is one of the most thoroughly dated prehistoric sites in western Europe. The until-now poorly dated, but very distinctive Initial Cantabrian Magdalenian lithic artifact assemblages are briefly summarized.

Klima-Änderungen im Pleistozän: Isotopenuntersuchungen an fossilen Seesedimenten aus dem Holstein-Interglazial Ost-Polens

In Ost-Polen erbohrte Seesedimente mit einer Mächtigkeit bis zu 55 m (Ossówka-See) dokumentieren das ganze Holstein-Interglazial und die Anfangsperiode der Saale-Eiszeit. An ausgewählten Bohrkernen der Seen von Ossówka und Wilczyn wurden palaeobiologische (Malakofauna, Palynologie und Pflanzen-Makroreste) und Isotopen-Untersuchungen durchgeführt. Die für den längsten (55 m) und vollständigsten Bohrkern nahe der Ortschaft Ossówka bestimmten C- und O-Isotopenwerte betragen: δ13C: Minimalwerte bis -6,4 ‰ für Ablagerungen am Beginn des Interglazials, Maximalwerte bis +10,0‰ für Ablagerungen aus der kalten Frühglazialperiode; δ18O: Maximalwerte bis -3,6 ‰ für Ablagerungen aus dem ersten Abschnitt des Interglazial-Optimums, Minimalwerte bis -10,1 ‰ für Ablagerungen aus der kältesten Periode unmittelbar vor der nächsten Vereisung. Generell gibt der Kurvenverlauf der O-Isotopenwerte gut die palynologisch dokumentierten Klimaveränderungen wieder. Im Profil sind jedoch zwei Perioden zu beobachten, in denen das Isotopenbild nicht mit der palynologischen Aussage übereinstimmt, einmal im klimatischen Interglazial-Optimum und zum anderen im jüngeren Teil des frühen Saale-Glazials. 1. Während des klimatischen Optimums des Holstein-interglazials (Pollen-Zone G und H) sprechen die Isotopenkurven der Seesedimente für relativ kühle Klimaverhältnisse. Dies kann durch eine Zunahme der Niederschlagsmenge, die zu einer Seespiegel-Erhöhung führte und/oder durch den Einfluß von isotopisch leichten Zuflüssen erklärt werden. 2. Im oberen Teil des Profils, der eine kühle, der Vereisung vorangehende Phase darstellt, erreichen die δ13C-und δ18O-Isotope unerwartet hohe Werte, was möglicherweise auf die Redeposition von "warmen" interglazialen Ablagerungen und/oder auf eine Zunahme der Evaporation unter trockenen Steppenklima-Bedingungen mit Seespiegel-Tiefständen zurückzuführen ist. Abkühlungsphasen fallen mit der Verschiebung der Sauerstoffisotopenverhältnisse in Richtung einer 18O- Verarmung zusammen.