End Of Oxygen Isotope Stage Research Articles

The chronostratigraphy of the latest Middle Pleistocene aeolian and alluvial activity on the Island of Hvar, eastern Adriatic, Croatia

Pleistocene aeolian sands and alluvial deposits can frequently be traced along the Mediterranean coast. Such deposits also exist along the eastern Adriatic coast and the nearby islands. Four stratigraphical sections of these deposits were studied on the Island of Hvar with the purpose of establishing a chronological framework of the aeolian–alluvial depositional system, using luminescence dating and magnetic susceptibility stratigraphy. Luminescence dating was applied on coarse‐grained feldspar and quartz grains separated from the sands. Both quartz optically stimulated luminescence (OSL) and feldspar post‐IR infrared stimulated luminescence (pIRIR) age estimates are in good agreement, with values ranging between 167±24 to 120±12 ka (OSL) and 179±18 to 131±18 ka (pIRIR measured at 290 °C) after a fading correction for the pIRIR signal. The results can be clearly correlated to around the end of oxygen isotope stage (OIS) 6 and the beginning of OSI 5, indicating that the aeolian accumulation of sands was a result of the Penultimate Glacial and climate fluctuations at the beginning of the Last Interglacial. Variations in magnetic susceptibility (MS) data can be interpreted alongside these dating results; several stronger peaks detected at the very end of the Penultimate Glacial and the initial stage of the Last Interglacial cycle most probably indicates more intensive pedogenesis resulting from a more favourable climate, probably because of climate changes. Breccias related to major bounding surfaces in association with evidence of soil formation and bioturbation could be the result of more favourable climate conditions and changes during the transition from OIS 6 to OIS 5 (Penultimate Glacial–Last Interglacial). These results are in agreement with similar data from the wider Mediterranean area.

A raised OIS 3 sea level recorded in coastal sediments, southern Changjiang delta plain, China

The distribution of marine-influenced oxygen isotope stage (OIS) 5 to OIS 1 sediments was examined in several late Quaternary boreholes from the southern Changjiang (Yangtze) delta plain, China, using different dating methods including OSL, U-series, AMS 14C and paleomagnetism. Results demonstrate that coastal and estuarine deposition during OIS 5 and OIS 3 occurred throughout the study area. However, Holocene transgressive sediments were absent on the Taihu block. The burial depth of intertidal to subtidal sediment deposited during OIS 5e records 30–80m subsidence caused by sediment compaction and tectonic movement since that time. However, coastal sediments formed during the late phase of OIS 3 were buried to a depth of ca. 6–15m in the Taihu Lake area, while the burial depth increased eastward to ca. 45–60m on the coastal plain. This phenomenon, combined with the distribution of Holocene marine strata, indicates at least 25–30m uplift of the Taihu block since the end of OIS 3. We suggest that this uplift was mainly caused by the differential subsidence due to substantial amount of post-glacial deposition by the Changjiang and Huanghe Rivers on the continental shelf of east China marginal sea.

The Sessano intra-montane basin: New multi-proxy data for the Quaternary evolution of the Molise sector of the Central-Southern Apennines (Italy)

An integrated geomorphological, geological–structural and stratigraphic approach was applied to the Sessano intra-montane basin (Molise, Central-Southern Apennines) to understand the Quaternary environmental and sedimentary evolution of the basin and the surrounding areas. The morpho-evolutionary and sedimentary changes were mainly controlled by tectonics and strongly influenced by the huge amount of volcaniclastic input from the Roccamonfina volcano (located ca. 50 km to the south-west) as well as by climatic changes. Chronological constraints, supported by 40Ar/ 39Ar ages of tephra layers, archaeo-tephro-stratigraphy and pollen analysis, permit identification of the main phases of the geological–geomorphologic evolution of the Sessano basin from the Middle Pleistocene onwards. The sedimentation within the basin was controlled by NE–SW extensional tectonics and occurred from the end of Oxygen Isotope Stage (OIS) 15 to the beginning of OIS 11 allowing the deposition of ca. 85 m of fluvial to lacustrine sediments, mainly made up of reworked volcaniclastic material. The first phase of sedimentation was lacustrine, while an important sedimentary change from lacustrine to fluvial-marshy environment occurred during OIS 14. After this phase, the variable input of volcaniclastic material from the Roccamonfina volcano together with climatic influences caused repeated changes from palustrine to fluvial sedimentation, and the formation of various palaeosols present mainly in the upper portion of the infill. Towards the end of OIS 11, NNW–SSE extensional tectonics caused the tilting of the fill succession and the drying up of the basin. The fill succession was then affected by fluvial erosion and denudation that generated an erosion surface nowadays hanging at 700–720 m asl. This surface can be related to the limbs of a palaeo-surface at about 600 m asl present in the adjacent Carpino-Le Piane intra-montane basin and referred to a fourth order, Tyrrhenian-ward oriented palaeo-landscape. This palaeo-landscape can be dated to ca. 350–300 ky and, therefore, represents an important morpho-chronological stage. It provides a robust maximum and minimum age framework for reconstructing the geological and geomorphological evolution of the study area and, in general, of the Molise Apennines including the Boiano, Carpino-Le Piane and Sessano intra-montane basins. In particular, the morpho-chronological data from the Sessano basin allow us to date more precisely the main tectonic phases that occurred during the Middle Pleistocene in this sector of the Apennine chain. Finally, the multi-proxy data derived from the Sessano basin can be compared and integrated with those referring to other proximal intra-montane basins in order to improve our knowledge on the relationships between tectonics, volcanism and climate and the stratigraphic–sedimentary features, geomorphologic evolution and palaeoenvironmental changes that characterized the Central-Southern Apennines during Middle Pleistocene.

Alluvial pedogenesis in Pleistocene and Holocene Mississippi River deposits: Effects of relative sea-level change

Research Article| November 01, 2001 Alluvial pedogenesis in Pleistocene and Holocene Mississippi River deposits: Effects of relative sea-level change Whitney J. Autin; Whitney J. Autin 1Department of the Earth Sciences, State University of New York, College at Brockport, Brockport, New York 14420, USA Search for other works by this author on: GSW Google Scholar Andres Aslan Andres Aslan 1Department of the Earth Sciences, State University of New York, College at Brockport, Brockport, New York 14420, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Whitney J. Autin 1Department of the Earth Sciences, State University of New York, College at Brockport, Brockport, New York 14420, USA Andres Aslan 1Department of the Earth Sciences, State University of New York, College at Brockport, Brockport, New York 14420, USA Publisher: Geological Society of America Received: 22 May 2000 Revision Received: 31 Jan 2001 Accepted: 27 Apr 2001 First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2001) 113 (11): 1456–1466. https://doi.org/10.1130/0016-7606(2001)113<1456:APIPAH>2.0.CO;2 Article history Received: 22 May 2000 Revision Received: 31 Jan 2001 Accepted: 27 Apr 2001 First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Whitney J. Autin, Andres Aslan; Alluvial pedogenesis in Pleistocene and Holocene Mississippi River deposits: Effects of relative sea-level change. GSA Bulletin 2001;; 113 (11): 1456–1466. doi: https://doi.org/10.1130/0016-7606(2001)113<1456:APIPAH>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Comparison of Pleistocene and Holocene soils developed in Mississippi River meander-belt deposits in Louisiana illustrates the influence of relative sea-level change on pedogenesis. Holocene and Pleistocene meander belts have similar landscape morphologies, lithofacies, and soil characteristics, and probably formed under similar hydrologic regimes. The Pleistocene Avoyelles Prairie meander belt is now terraced, but it was originally graded to a lower relative sea-level position than the Holocene flood plain. Holocene alluvial soils are generally weakly expressed cumulative profiles with abundant redoximorphic features, and formed on an aggrading flood plain with a shallow fluctuating water table. The soil morphology varies with respect to landscape position and overbank lithofacies.Pleistocene alluvial paleosols show evidence for two stages of pedogenesis. During the first stage of pedogenesis, water-table fluctuations and flood-plain aggradation produced profiles with color mottles, iron and carbonate nodules, and weak B and C horizons, similar to Holocene flood-plain soils. The second stage of pedogenesis occurred after the Avoyelles Prairie was terraced and the regional water table fell a minimum of 30 m. Improved soil drainage created oxidizing and acidic conditions, removed free carbonates, dehydrated iron oxides, and transformed clay minerals. This stage produced Pleistocene profiles with brighter matrix and mottle hues, lower pH values, larger and harder iron nodules, and greater kaolinite contents than comparable Holocene flood-plain soils.The primary influence on regional water- table lowering in the southern Lower Mississippi Valley was relative sea-level fall. Mississippi River flood-plain lowering adjacent to the Avoyelles Prairie most likely occurred between the end of oxygen isotope stage 3 and the maximum period of valley entrenchment, during oxygen isotope stage 2. Water-table fall affected pedogenic processes a minimum of 400 km upvalley of the continental shelf margin. Pleistocene Mississippi River paleosols represent excellent analogs for interpreting ancient alluvial paleosols formed during episodes of base-level fall and valley incision. As fluvial entrenchment terraced the meandering Avoyelles Prairie, a pedogenic threshold was crossed that altered the pathway of chemical weathering. The complexity of a multiple-step pedogenic history also highlights the fact that interpretation of relative profile development as a function of time can be problematic. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Zircon fission track age for middle Pleistocene Rangitawa Tephra, New Zealand: stratigraphic and paleoclimatic significance

Rangitawa Tephra is an important stratigraphic marker in mid-Pleistocene marine and terrestrial sequences in New Zealand and adjacent ocean basins. Zircon fission track ages (ZFTA) on Rangitawa Tephra from five sites in the southern North Island yield mean site ages in the range 0.34 to 0.40 Ma with a weighted mean of 0.35±0.04 Ma (1 σ). On the basis of glass shard major-element chemistry, ferromagnesian mineralogy, ZFTA and similarity of paleomagnetic dates of proposed tephra correlatives in deep-sea cores, it is concluded that Rangitawa Tephra represents a major eruptive event in the Taupo Volcanic Zone most probably associated with eruption of the Whakamaru-group ignimbrites (0.35−0.39 Ma) or less likely the Paeroa Range Group Ignimbrites (0.36–0.38 Ma). Pollen analyses from two onshore sites, together with regional loess stratigraphy, show that Rangitawa Tephra was erupted during a glacial period. The ZFTA and previously reported oxygen isotope data from DSDP Site 594 indicate that Rangitawa Tephra was erupted near the end of oxygen isotope stage 10.

Palynological evidence for upper Putikian (middle Pleistocene) interglacial and glacial climates at Rangitawa Stream, South Wanganui Basin, New Zealand

Abstract Putikian strata exposed at Rangitawa Stream, Palmerston North, New Zealand, include the Rangitawa Fossil Beds, containing Pecten bene-dictus marwicki (Finlay), and the overlying Rangitawa Pumice (c. 370 000 years B.P.). Palynofloras indicate that a warm, humid climate existed when the Rangitawa Fossil Beds were deposited in very shallow marine and estuarine environments. Beech-podocarp forest predominated in the coastal areas. Subsequently, a climatic deterioration occurred and Rangitawa Pumice fell when a cold, glacial climate had developed as indicated by palynofloras dominated by shrub and grassland taxa. Stratigraphic position, palynology, and the fission-track age of Rangitawa Pumice suggest that the Rangitawa Fossil Beds were deposited near the end of oxygen isotope stage 11, and Rangitawa Pumice fell near the beginning of oxygen isotope stage 10.

New Faunal and Isotopic Evidence on the Late Weichselian—Holocene Oceanographic Changes in the Norwegian Sea

Downcore studies of planktonic and benthonic foraminifera and δ18O and δ13C in the planktonic foraminifer Neogloboquadrina pachyderma (sin.) in two piston cores from the southern part of the Norwegian Sea suggest large changes in the oceanic circulation pattern at the end of oxygenisotope stage 2 and in the early part of stage 1. Prior to oxygen-isotope Termination IA (16,000–13,000 yr B.P.), an isolated watermass with lower oxygen content and temperature warmer than today existed below a low salinity ice-covered surface layer in the Norwegian Sea. Close to Termination IA, well-oxygenated deep water, probably with positive temperatures, was introduced. This deep water, which must have had physical and/or chemical parameters different from those of present deep water in the Norwegian Sea, could have been introduced from the North Atlantic or been formed within the basin by another mechanism than that which forms the present deep water of the Norwegian Sea. A seasonal ice cover in the southern part of the Norwegian Sea is proposed for the period between Termination IA and the beginning of IB (close to 10,000 yr B.P.). The present situation, with strong influx of warm Atlantic surface-water and deep-water formation by surface cooling, was established at Termination IB.