scholarly journals Preliminary study of fossil freshwater molluscs from the Plio-Pleistocene Kathmandu Basin sediments, central Nepal

2001 ◽  
Vol 25 ◽  
Author(s):  
Damayanti Gurung ◽  
Katsumi Takayasu ◽  
Hasko Nesemann
Keyword(s):  
Lacustrine Sediments ◽  
Early Pleistocene ◽  
Bivalve Species ◽  
Faunal Composition ◽  
Late Pliocene ◽  
Freshwater Molluscs ◽  
Central Nepal ◽  
Molluscan Fauna ◽  
Preliminary Study ◽  
Molluscan Species

Fossils of freshwater Mollusca from the fluvio-lacustrine sediments of the Kathmandu Basin are collected from localities in the upper part of the Lukundol Formation, of Late Pliocene to Early Pleistocene age, and the Gokarna Formation, of Late Pleistocene age. Despite the temporal differences of the two localities, the dominant molluscan species in each locality are similar. The fossil molluscan fauna in the older Lukundol Formation is entirely composed of prosobranch gastropod shells belonging to the genus Bellamya and opercula of the genus Digoniostoma. The fauna in the younger Gokarna Formation includes similar prosobranch species with addition of one prosobranch species, along with three pulmonate gastropods, an unidentified terrestrial gastropod and a bivalve species. The additional prosobranch species belong to the genus Gabbia, and the pulmonate gastropods are of the genera Lymnaea, Gyraulus, and Planorbis. The only bivalve species belong to the genus Pisidium. In the Lukundol Formation, fossil molluscan shells are abundant but poor in number of species and the assemblage is dominated by lacustrine taxa preferring permanent lentic water body of shallow depth. Conversely, in the Gokarna Formation, species diversity is comparatively higher, with inhabitant of the shallow lacustrine to marginal less stable habitats. The fossil molluscan faunal composition is more similar to the recent fauna that inhabits the warmer southern Terai region of Nepal.

scholarly journals Late Pliocene and early Pleistocene environments of the north-eastern Russian Arctic inferred from the Lake El'gygytgyn pollen record

2013 ◽  
Vol 9 (4) ◽  
pp. 4599-4653 ◽  
Author(s):  
A. A. Andreev ◽  
P. E. Tarasov ◽  
V. Wennrich ◽  
E. Raschke ◽  
U. Herzschuh ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Lacustrine Sediments ◽  
Early Pleistocene ◽  
Pollen Record ◽  
Russian Arctic ◽  
Coprophilous Fungi ◽  
Climate Conditions ◽  
Late Pliocene ◽  
The North ◽  
Lake El’Gygytgyn

Abstract. The 318 m thick lacustrine sediment record in Lake El'gygytgyn, northeastern Russian Arctic cored by the international El'gygytgyn Drilling Project provides unique opportunities allowing the time-continuous reconstruction of the regional paleoenvironmental history for the past 3.6 Myr. Pollen studies of the lower 216 m of the lacustrine sediments show their value as an excellent archive of vegetation and climate changes during the Late Pliocene and Early Pleistocene. About 3.50–3.35 Myr BP the vegetation at Lake El'gygytgyn, in nowadays tundra area, was dominated by spruce-larch-fir-hemlock forests. After ca. 3.4 Myr BP dark coniferous taxa gradually disappeared. A very pronounced environmental changes took place at ca. 3.305–3.275 Myr BP, corresponding with the Marine Isotope Stage (MIS) M2, when treeless tundra- and steppe-like habitats became dominant in the regional vegetation. Climate conditions were similar to those of Late Pleistocene cold intervals. Numerous coprophilous fungi spores identified in the pollen samples suggest the presence of grazing animals around the lake. Following the MIS M2 event, larch-pine forests with some spruce mostly dominated in the area until ca. 2.6 Myr BP, interrupted by colder and drier intervals ca. 3.04–3.02, 2.93–2.91, and 2.725–2.695 Myr BP. At the beginning of the Pleistocene, ca. 2.6 Myr BP, noticeable climatic deterioration occurred. Forested habitats changed to predominantly treeless and shrubby environments, which reflect a relatively cold and dry climate. Revealed peaks in green algae colonies (Botryococcus) around 2.53, 2.45, 2.320–2.305 and 2.175–2.150 Myr BP suggest a spread of shallow water environments. Few intervals (i.e. 2.55–2.53, ca. 2.37, and 2.35–2.32 Myr BP) with a higher presence of coniferous taxa (mostly pine and larch) document some relatively short-term climate ameliorations.

scholarly journals Late Pliocene and Early Pleistocene vegetation history of northeastern Russian Arctic inferred from the Lake El'gygytgyn pollen record

2014 ◽  
Vol 10 (3) ◽  
pp. 1017-1039 ◽  
Author(s):  
A. A. Andreev ◽  
P. E. Tarasov ◽  
V. Wennrich ◽  
E. Raschke ◽  
U. Herzschuh ◽  
...  
Keyword(s):  
Vegetation History ◽  
Lacustrine Sediments ◽  
Early Pleistocene ◽  
Pollen Record ◽  
Russian Arctic ◽  
Coprophilous Fungi ◽  
Climate Conditions ◽  
Late Pliocene ◽  
Lake El’Gygytgyn ◽  
History Of

Abstract. The 318 m thick lacustrine sediment record from Lake El'gygytgyn, northeastern Russian Arctic cored by the international El'gygytgyn Drilling Project provides unique opportunities for the time-continuous reconstruction of the regional paleoenvironmental history for the past 3.6 Myr. Pollen studies of the lower 216 m of the lacustrine sediments demonstrate their value as an excellent archive of vegetation and climate changes during the Late Pliocene and Early Pleistocene. About 3.5–3.35 Myr BP, the vegetation at Lake El'gygytgyn, now an area of tundra was dominated by spruce-larch-fir-hemlock forests. After ca. 3.35 Myr BP dark coniferous taxa gradually disappeared. A very pronounced environmental change took place ca. 3.31–3.28 Myr BP, corresponding to the Marine Isotope Stage (MIS) M2, when treeless tundra- and steppe-like habitats became dominant in the regional vegetation. Climate conditions were similar to those of Late Pleistocene cold intervals. Numerous coprophilous fungi spores identified in the pollen samples suggest the presence of grazing animals around the lake. Following the MIS M2 event, larch-pine forests with some spruce mostly dominated the area until ca. 2.6 Myr BP, interrupted by colder and drier intervals ca. 3.043–3.025, 2.935–2.912, and 2.719–2.698 Myr BP. At the beginning of the Pleistocene, ca. 2.6 Myr BP, noticeable climatic deterioration occurred. Forested habitats changed to predominantly treeless and shrubby environments, which reflect a relatively cold and dry climate. Peaks in observed green algae colonies (Botryococcus) around 2.53, 2.45, 2.32–2.305, 2.20 and 2.16–2.15 Myr BP suggest a spread of shallow water environments. A few intervals (i.e., 2.55–2.53, ca. 2.37, and 2.35–2.32 Myr BP) with a higher presence of coniferous taxa (mostly pine and larch) document some relatively short-term climate ameliorations during Early Pleistocene glacial periods.

scholarly journals Millennial-scale climate change and oceanic processes in the Late Pliocene and Early Pleistocene

2001 ◽  
Vol 16 (5) ◽  
pp. 535-543 ◽  
Author(s):  
Katherine Mc Intyre ◽  
Margaret L. Delaney ◽  
A. Christina Ravelo
Keyword(s):  
Climate Change ◽  
Early Pleistocene ◽  
Late Pliocene ◽  
Millennial Scale

scholarly journals Khorbas: a Lower Palaeolithic site on Qeshm Island in the Persian Gulf

Antiquity ◽  
2017 ◽  
Vol 91 (358) ◽  
Author(s):  
Sirvan Mohammadi Ghasrian
Keyword(s):  
Persian Gulf ◽  
Early Pleistocene ◽  
Fars Province ◽  
Potential Importance ◽  
Zagros Mountains ◽  
The West ◽  
Qeshm Island ◽  
Late Pliocene ◽  
The Persian Gulf ◽  
Lower Palaeolithic

Despite the potential importance of southern Iran, and the Persian Gulf area in particular, for discussions on the dispersal of early hominins from Africa into Eurasia during the late Pliocene and early Pleistocene (Bar-Yosef & Belfer-Cohen 2001; Rose 2010), this area has remained almost unexplored until recently. Historically, Palaeolithic survey and excavations in Iran have mainly concentrated in western regions, especially the Zagros Mountains. As a result of recent studies, however, evidence for Palaeolithic sites in the southern regions of Iran, from Fars province to Qeshm Island, has greatly increased (Dashtizade 2009, 2010). Even with this improvement, no sites of Lower Palaeolithic date have yet been reported from the southern coastal areas on one of the proposed early hominin routes into Eurasia. As a result, it has been suggested that the few Lower Palaeolithic sites reported from other parts of Iran, especially in the west (e.g. Biglari & Shidrang 2006), were not populated from the south.

Molluscan biostratigraphy of the lower River Bend Formation at the Martin Marietta Quarry, New Bern, North Carolina

1991 ◽  
Vol 65 (1) ◽  
pp. 80-118 ◽  
Author(s):  
Thomas J. Rossbach ◽  
Joseph G. Carter
Keyword(s):  
North Carolina ◽  
Coastal Plain ◽  
Warm Water ◽  
Gulf Coastal Plain ◽  
Generic Level ◽  
Evolutionary Transitions ◽  
Molluscan Fauna ◽  
Molluscan Diversity ◽  
Molluscan Species ◽  
River Bend

The lower River Bend Formation at the Martin Marietta New Bern quarry in Craven County, North Carolina, contains a diverse and abundant moldic molluscan fauna. This fauna, reconstructed by latex casts, suggests a Vicksburgian or a post-Vicksburgian, pre-Chickasawhayan age for the New Bern exposure. Forty-one molluscan species and subspecies are presently identified from the lower River Bend Formation, 11 of which are new: Turritella caelatura alani, Turritella neusensis, Galeodaria britti, Phalium newbernensis, Cymatium planinodum, Oocorys vadosus, Ecphora wheeleri, Lyria concinna, Scaphella saintjeani, Turricula (Orthosurcula) aequa, and Lucina (Stewartia) micraulax. This fauna is virtually identical at the generic level and similar at the species level to the Vicksburgian faunas of the Gulf Coastal Plain. About 37 percent of the New Bern species also occur in the Vicksburgian of Mississippi, although many of these species reach considerably larger sizes at New Bern. Apparent evolutionary transitions between previously known Vicksburgian and Chickasawhayan mollusks suggest a time of deposition intermediate between these two Oligocene stages.Moderately high molluscan diversity, the abundance of characteristically warm-water genera, and associated carbonate-rich sediments suggest that the lower River Bend Formation represents a subtropical, open-marine, predominantly carbonate environment immediately seaward of a nearshore lagoonal or barrier island complex.The lower River Bend Formation at New Bern differs faunally, climatically, and sedimentologically from the upper River Bend Formation in quarry exposures near Belgrade, North Carolina. The upper River Bend Formation contains a lower diversity molluscan fauna with marked dominance diversity and few warm-water taxa. It represents a slightly cooler nearshore, open-marine environment in a transitional siliciclastic-carbonate sedimentary regime. The considerable taxonomic and sedimentologic differences between the lower and upper parts of the River Bend Formation corroborate microfossil evidence suggesting that they represent temporally distinct depositional cycles.

scholarly journals Contribution of changes in opal productivity and nutrient distribution in the coastal upwelling systems to Late Pliocene/Early Pleistocene climate cooling

2012 ◽  
Vol 8 (5) ◽  
pp. 1435-1445 ◽  
Author(s):  
J. Etourneau ◽  
C. Ehlert ◽  
M. Frank ◽  
P. Martinez ◽  
R. Schneider
Keyword(s):  
Southern Ocean ◽  
Coastal Upwelling ◽  
Atmospheric Co2 ◽  
Early Pleistocene ◽  
Silicon Isotope ◽  
Time Interval ◽  
Nutrient Distribution ◽  
Biogenic Opal ◽  
Late Pliocene ◽  
Polar Ocean

Abstract. The global Late Pliocene/Early Pleistocene cooling (~3.0–2.0 million years ago – Ma) concurred with extremely high diatom and biogenic opal production in most of the major coastal upwelling regions. This phenomenon was particularly pronounced in the Benguela upwelling system (BUS), off Namibia, where it is known as the Matuyama Diatom Maximum (MDM). Our study focuses on a new diatom silicon isotope (δ30Si) record covering the MDM in the BUS. Unexpectedly, the variations in δ30Si signal follow biogenic opal content, whereby the highest δ30Si values correspond to the highest biogenic opal content. We interpret the higher δ30Si values during the MDM as a result of a stronger degree of silicate utilisation in the surface waters caused by high productivity of mat-forming diatom species. This was most likely promoted by weak upwelling intensity dominating the BUS during the Late Pliocene/Early Pleistocene cooling combined with a large silicate supply derived from a strong Southern Ocean nutrient leakage responding to the expansion of Antarctic ice cover and the resulting stratification of the polar ocean 3.0–2.7 Ma ago. A similar scenario is hypothesized for other major coastal upwelling systems (e.g. off California) during this time interval, suggesting that the efficiency of the biological carbon pump was probably sufficiently enhanced in these regions during the MDM to have significantly increased the transport of atmospheric CO2 to the deep ocean. In addition, the coeval extension of the area of surface water stratification in both the Southern Ocean and the North Pacific, which decreased CO2 release to the atmosphere, led to further enhanced atmospheric CO2 drawn-down and thus contributed significantly to Late Pliocene/Early Pleistocene cooling.

scholarly journals Petrography of the Siwalik sandstones, Amlekhganj-Suparitar area, central Nepal Himalaya

2003 ◽  
Vol 28 ◽  
Author(s):  
Naresh Kazi Tamrakar ◽  
Shuichiro Yokota ◽  
Suresh Das Shrestha
Keyword(s):  
Middle Miocene ◽  
Foreland Basin ◽  
Early Pleistocene ◽  
Nepal Himalaya ◽  
Central Nepal ◽  
Present Study Area ◽  
Mean Grain Size ◽  
Siwalik Group ◽  
Variation Trends ◽  
The Himalaya

Middle Miocene to early Pleistocene sedimentary sequence deposited in the foreland basin of the Himalaya is represented by the Siwalik Group. In the present study area the Siwalik Group extends in a NW-SE direction and well-exposed. Forty­four sandstone samples were studied for texture, fabric and composition in order to assess their petrographic properties and variation trends of these properties in stratigraphic levels. Sandstones were classified into sublitharenite, subarkose, lithic arenite, arkosic arenite and feldspathic graywacke and further thirteen sub-clans. Mean grain size (M) and Trask sorting coefficient (So) increase up-section. Recalculated quartz, matrix, modified maturity index (MMI), total cement (Ct), cement versus matrix index (CMI) and ratio of strong cement over total cement ((Cfc/Cs)/Ct) also increase, whilst packing proximity (PP), packing density (PD) and consolidation factor (Pcc) decrease up-section showing distinct trends, and therefore, these properties are promising in recognizing the older sandstones from the younger ones.

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