Early Pleistocene volcanism and glaciation in central Yukon: a new chronology from field studies and paleomagnetism

1996 ◽  
Vol 33 (6) ◽  
pp. 904-916 ◽  
Author(s):  
L. E. Jackson Jr ◽  
R.W. Barendregt ◽  
J. Baker ◽  
E. Irving
Keyword(s):  
Secular Variation ◽  
Field Studies ◽  
Early Pleistocene ◽  
Pleistocene Glaciations ◽  
Matuyama Chron ◽  
Filling Phase ◽  
Pleistocene Volcanism ◽  
Low K ◽  
Radiometric Dates

The paleomagnetism of the Selkirk Volcanics and nearby stratified Pleistocene sediments was investigated to resolve the chronology of Early Pleistocene glaciations in central Yukon. Radiometric dates on these low-K basalts have proven to be erroneously old. Most sampled sediments and all basalts accurately record the paleofield and true reversals. The valley-filling phase of the Selkirk Volcanics was in part coeval with the younger pre-Reid glaciation. It was erupted during the Matuyama Chron, either post-Cobb Mountain Subchron or post-Jaramillo Subchron, over a period too brief to average secular variation. The older pre-Reid glaciation occurred after ca. 1.60 Ma and prior to the eruption of the Fort Selkirk tephra (pre-Jaramillo or pre-Cobb Mountain). Sediments investigated at Revenue Creek and Braden's Canyon are normally magnetized. The assigned Brunhes age is compatible with their occurrence in valleys that were cut or deepened sometime after the pre-Reid glaciations.

Paleomagnetic evidence for multiple Late Pliocene - Early Pleistocene glaciations in the Klondike area, Yukon Territory

2000 ◽  
Vol 37 (6) ◽  
pp. 863-877 ◽  
Author(s):  
D G Froese ◽  
R W Barendregt ◽  
R J Enkin ◽  
J Baker
Keyword(s):  
Yukon Territory ◽  
Early Pleistocene ◽  
Pleistocene Glaciations ◽  
Glacial Sediments ◽  
Late Pliocene ◽  
Matuyama Chron ◽  
Normal Polarity ◽  
Ice Wedge ◽  
Brunhes Chron ◽  
Cordilleran Ice Sheet

The Late Pliocene - Early Pleistocene terraces of the Klondike area provide a conformal record of sedimentation which marks the transition from preglacial to glacial conditions, and is one of the most complete records of glaciation and interglaciation in the northern Cordillera. Preglacial sedimentation is recorded in the Lower White Channel gravel that contains a reverse-normal polarity sequence. A re-aggradation of the nonglaciated valleys of the goldfields in response to Late Pliocene cooling is recorded by the Upper White Channel gravel, which is characterized by a dominant normal polarity with a lower reversal likely associated with the first ice-wedge casts. Klondike gravel interfingers with Upper White Channel and is normally magnetized, indicating an equivalent magnetostratigraphic unit. This glaciofluvial gravel provides evidence of extra-basinal clasts, marking a major reorganization of drainage associated with the first advance of the Cordilleran Ice Sheet in western Yukon Territory correlated with the Gauss chron (>2.58 Ma). An intermediate terrace in Klondike valley is overlain by 8 m of fluvial and glaciofluvial gravel named the Midnight Dome gravel. This gravel is mantled by 15 m of loess and hillslope deposits, named the Midnight Dome loess, which preserve at least three interglacial pollen assemblages, and a reverse-normal-reverse-normal polarity sequence assigned to the late Matuyama chron, including Jaramillo subchron (1.07-0.99 Ma), and early Brunhes chron (<0.78 Ma). The oldest glaciations here, based on the preferred interpretation, extend well into the Pliocene (>2.58 Ma) making these among the oldest glacial sediments in North America.

Stratigraphy and paleomagnetism of Late Pliocene and Pleistocene sediments in the Wellsch Valley and Swift Current Creek areas, southwestern Saskatchewan, Canada

1998 ◽  
Vol 35 (12) ◽  
pp. 1347-1361 ◽  
Author(s):  
R W Barendregt ◽  
E Irving ◽  
E A Christiansen ◽  
E K Sauer ◽  
B T Schreiner
Keyword(s):  
Late Pleistocene ◽  
Magnetic Polarity ◽  
Early Pleistocene ◽  
Western Canada ◽  
Marked Contrast ◽  
Glacial Deposits ◽  
Late Pliocene ◽  
Matuyama Chron ◽  
Reversed Polarity

The Late Pliocene and Pleistocene are represented in southern Saskatchewan by sequences of preglacial, glacial, and nonglacial deposits. These have been studied in surface exposures and bore cores and have been subdivided and correlated on the basis of their lithologies. In this study, new observations of magnetic polarity are presented. They reveal a lower preglacial sequence (Empress Group) with reversed polarity, and an upper normally magnetized sequence which contains glacial deposits of pre-Illinoian, Illinoian, and Wisconsinan age and which are correlative with the Saskatoon and Sutherland groups of central Saskatchewan. The reversed preglacial sequence is referred to the Matuyama Zone (Late Pliocene to Early Pleistocene: 2.58-0.78 Ma) and the normal glacial sequence to the Brunhes Zone (Middle to Late Pleistocene and Holocene: 0.78 Ma to present). In southern Saskatchewan there is no evidence of glaciation during the Late Pliocene and Early Pleistocene (Matuyama Chron) which is in marked contrast with parts of the Cordilleran region of western Canada where glaciations occur throughout this time.

Paleomagnetism of Quaternary and late Tertiary sediments on Mokowan Butte, southwestern Alberta

1991 ◽  
Vol 28 (12) ◽  
pp. 1956-1964 ◽  
Author(s):  
R. W. Barendregt ◽  
E. Irving ◽  
E. T. Karlstrom
Keyword(s):  
British Columbia ◽  
Geomagnetic Field ◽  
Early Pleistocene ◽  
Glacial Sediments ◽  
Banks Island ◽  
Quaternary Sequences ◽  
Matuyama Chron ◽  
Late Tertiary ◽  
Unconsolidated Sediment ◽  
Accurate Record

Mokowan Butte in southwestern Alberta is capped by 32 m of unconsolidated sediment comprising five tills and their associated paleosols. Previous stratigraphic work has indicated that the older tills are probably Early Pleistocene to late Tertiary in age. Paleomagnetic studies, based on 125 samples, show that the uppermost till–paleosol unit and the modern subsoil are normally magnetized, whereas the till–paleosol units from the middle of the sequence have reversed magnetization. We argue that these belong to the Brunhes and Matuyama polarity zones, respectively. The lowest part of the sequence has not been studied in detail and is generally too coarse for paleomagnetic sampling, and samples that have been obtained contain no accurate record of the paleofield. These new data, together with those from Wellsch Valley in Saskatchewan, Banks Island in the Northwest Territories, Fort Selkirk in the Yukon, and Merritt in British Columbia, bring to five the number of early Quaternary sequences in Canada that have yielded a record of glacial sediments deposited during the Matuyama chron, and hence record glacial events prior to the last reversal of the geomagnetic field (720 ka).

scholarly journals Snapshots of the Greenland ice sheet configuration in the Pliocene to early Pleistocene

2011 ◽  
Vol 57 (205) ◽  
pp. 871-880 ◽  
Author(s):  
Anne M. Solgaard ◽  
Niels Reeh ◽  
Peter Japsen ◽  
Tove Nielsen
Keyword(s):  
Flow Model ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Early Pleistocene ◽  
Pleistocene Glaciations ◽  
Ice Flow ◽  
Late Pliocene ◽  
Ice Caps ◽  
Climate Reconstructions

AbstractThe geometry of the ice sheets during the Pliocene to early Pleistocene is not well constrained. Here we apply an ice-flow model in the study of the Greenland ice sheet (GIS) during three extreme intervals of this period constrained by geological observations and climate reconstructions. We study the extent of the GIS during the Mid-Pliocene Warmth (3.3–3.0 Ma), its advance across the continental shelf during the late Pliocene to early Pleistocene glaciations (3.0–2.4 Ma) as implied by offshore geological studies, and the transition from glacial to interglacial conditions around 2.4 Ma as deduced from the deposits of the Kap København Formation, North Greenland. Our experiments show that no coherent ice sheet is likely to have existed in Greenland during the Mid-Pliocene Warmth and that only local ice caps may have been present in the coastal mountains of East Greenland. Our results illustrate the variability of the GIS during the Pliocene to early Pleistocene and underline the importance of including independent estimates of the GIS in studies of climate during this period. We conclude that the GIS did not exist throughout the Pliocene to early Pleistocene, and that it melted during interglacials even during the late Pliocene climate deterioration.

Palaeoenvironmental and climatic inferences from the late early Pleistocene lacustrine deposits in the eastern Tiberino Basin (central Italy)

2018 ◽  
Vol 90 (1) ◽  
pp. 201-221 ◽  
Author(s):  
Roberto Bizzarri ◽  
Paolo Corrado ◽  
Donatella Magri ◽  
Edoardo Martinetto ◽  
Daniela Esu ◽  
...  
Keyword(s):  
Central Italy ◽  
Early Pleistocene ◽  
Interglacial Period ◽  
Pollen Record ◽  
Southern Europe ◽  
Climate Conditions ◽  
Lacustrine Deposits ◽  
Matuyama Chron ◽  
Chemical Composition Of Water ◽  
Definition Of

AbstractWithin the Neogene-Quaternary evolution of the Mediterranean intermountain basins, the eastern Tiberino Basin provides new multifaceted chronological, biostratigraphic, palaeoecological, and palaeoenvironmental information, appreciably improving the knowledge of palaeoenvironmental and climate conditions during the middle-late Matuyama Chron (late early Pleistocene). Shallow to relatively deep lacustrine deposits and alluvial plain deposits, magnetostratigraphically calibrated, hold malacofaunas, ostracofaunas, and carpological remains, as well as a pollen record. Palaeocarpological remains widely originated from the local (azonal) vegetation of waterlogged environments. Nonetheless, some taxa show transitional morphology between possibly extinct Pliocene-Pleistocene forms and living taxa. The pollen record highlights a conifer-dominated forest phase, indicating a temperate-wet interglacial period, well aligned inside the schemes for the same latitudinal band. The abundance of tree taxa currently absent from the Italian peninsula points to pre-Jaramillo late early Pleistocene biostratigraphical characters, here compared to other sections from central Italy, and contributes to a better definition of modes and timing of their disappearance in southern Europe. Malacofaunas and ostracods, still with late early Pleistocene features, together with Charophyte, mark repeated fluctuations in energy, temperature, and chemical composition of water. The overall record identifies an incipient diachronous cooling trend, for the first time recognized in southern Europe.

Evidence for an Early Pleistocene glaciation in the Okanagan Valley, southern British Columbia

2014 ◽  
Vol 51 (2) ◽  
pp. 125-141 ◽  
Author(s):  
Murray A. Roed ◽  
René W. Barendregt ◽  
Jeff A. Benowitz ◽  
C.A.S. Smith ◽  
P.T. Sanborn ◽  
...  
Keyword(s):  
British Columbia ◽  
First Nation ◽  
Early Pleistocene ◽  
Pleistocene Glaciation ◽  
Pleistocene Glaciations ◽  
The West ◽  
Glacial Sediments ◽  
Fabric Analysis ◽  
Minimum Age ◽  
Okanagan Valley

Depositional evidence of Early Pleistocene glaciations in British Columbia are documented at only a few sites. Near Kelowna, in southern British Columbia, a construction project exposed glacial sediments beneath Lambly Creek Basalt, providing a minimum age for this glaciation. The basalt is composed of a number of flows yielding ages that range from 0.76 ± 0.11 to 1.5 ± 0.1 Ma. The sediments consist of a diamicton, interpreted to be till, up to 3 m thick mantled by a weakly developed paleosol. The diamicton is underlain by fluvial sands up to 5 m thick, in places revealing injection features, and minor faulting. A unit of stratified gravel underlain by grey clay is inferred to underlie the exposed sediments, based on nearby outcrops and excavations. Sediments and overlying basalts are normally magnetized and are assigned to the Jaramillo normal subchron (1.069–0.987 Ma). The till is here referred to as the Westbank First Nation Till. It is Early Pleistocene in age and represents the earliest evidence of glaciation in the Okanagan Valley. Stone fabric analysis and clast lithologies suggest that ice movement was from northwest to southeast, and is here referred to as the West Kelowna Advance; we infer that this advance was part of a larger regional glaciation. Other Early Pleistocene glaciations in the Cordillera are briefly reviewed.

scholarly journals Fluvial stacking due to plate collision and uplift during the Early Pleistocene in Cyprus

2010 ◽  
Vol 2 (4) ◽  
Author(s):  
Wolfgang Schirmer ◽  
Josef Weber ◽  
Valerian Bachtadse ◽  
Marcelle BouDagher-Fadel ◽  
Friedrich Heller ◽  
...  
Keyword(s):  
Early Pleistocene ◽  
Eurasian Plate ◽  
The North ◽  
The Earth ◽  
Matuyama Chron ◽  
Southern Cyprus ◽  
River Deposits ◽  
River Plain ◽  
Restraining Bend ◽  
Landscape Formation

AbstractSouthern Cyprus is situated within a mosaic terrane that has been fragmented between the northward drifting African and Arabian plates and the Eurasian plate. Enormous uplift of the earth mantle in the Tróodos Mountains is explained by two models. The subduction model explains subduction along the Cyprean arc to be the driving force for uplift whereas after the restraining bend model westward squeezing of Cyprus along strike-slip faulting is responsible for the enormous uplift at restraining bends. Since its emergence as an island in early Miocene times, landscape formation on Cyprus has been strongly controlled by this uplift. Until the Plio-Pleistocene, a strait belt separated the southern unroofed ophiolitic core region-the Tróodos Mountains-from the folded Kyrenia range to the north. This former sea basin, nowadays the Mesaoría Basin, is linked with the Tróodos Mountains by a dissected glacis with a thick cover of river deposits. The highest and oldest river deposits (Apalós Formation) were studied in the Vlokkariá hill southwest of Lefkosía. The 45.5 m thick Apalós Formation of Early Pleistocene age exhibits 24 sedimentary units (Fluviatile Series). Their magnetostratigraphical characters align with the Matuyama chron including the Olduvai and Jaramillo subchrons thus comprising about 1.15 Ma within the Early Pleistocene. This fluvial stack indicates a very flat and deeply lying river environment flowing from a slowly uplifting Tróodos hinterland. It happened during the end of Early Pleistocene when the enhanced Tróodos uplift started the dissection of the stacked river plain.

The Eastern Beringian vole Microtus deceitensis (Rodentia, Muridae, Arvicolinae) in Late Pliocene and Early Pleistocene faunas of Alaska and Yukon

2003 ◽  
Vol 60 (1) ◽  
pp. 84-93 ◽  
Author(s):  
John E. Storer
Keyword(s):  
Fission Track ◽  
Tooth Enamel ◽  
Magnetic Polarity ◽  
Yukon Territory ◽  
Type Locality ◽  
Early Pleistocene ◽  
Late Pliocene ◽  
Radiometric Dates

AbstractThe fossil vole Microtus deceitensis occurs in Early Pleistocene deposits at Fort Selkirk, Yukon Territory, and Late Pliocene beds at the type locality, Cape Deceit, Alaska. Analyses of simple vs complex morphotypes in the cheek teeth, and of differentiation of tooth enamel, show that the Cape Deceit sample of M. deceitensis is less derived, and thus appears to be older, than the Fort Selkirk sample. The fossiliferous deposits at Fort Selkirk are well constrained by fission-track and radiometric dates and are 1.5 to 1.7 myr. Sediments at Cape Deceit bear a normal magnetic polarity, are correlated with the Olduvai subchron, and probably are latest Pliocene.

Magnetic Stratigraphy and a Test for Block Rotation of Sedimentary Rocks within the San Andreas Fault Zone, Mecca Hills, Southeastern California

1987 ◽  
Vol 27 (1) ◽  
pp. 30-40 ◽  
Author(s):  
Shih-Bin R. Chang ◽  
Clarence R. Allen ◽  
Joseph L. Kirschvink
Keyword(s):  
Fault Zone ◽  
San Andreas Fault ◽  
Late Quaternary ◽  
Early Pleistocene ◽  
Tectonic Activity ◽  
Block Rotation ◽  
San Andreas ◽  
Matuyama Chron ◽  
Least Squares Fit ◽  
Tectonic Rotation

AbstractA 500-m section of the Palm Spring Formation in the southern Mecca Hills, located within the San Andreas fault zone in southeastern California, has been paleomagnetically sampled to determine possible tectonic rotation in this area and to establish time-stratigraphic control. This work was partly stimulated by the fact that 80 km farther south, previous studies demonstrated 35° of postdepositional rotation in the Palm Spring Formation of the Vallecito-Fish Creek basin east of the Elsinore fault. Several lines of evidence suggest that hematite is the main magnetic carrier of the Mecca Hills samples. Large anhedral hematite grains observed in magnetic extracts and a positive fold test imply a detrital origin of the remanence. The polarity reversal patterns, together with earlier vertebrate paleontologic studies, restrict the time span for deposition of this unit to the middle-late Matuyama chron (2.0–0.75 myr ago), thus of uppermost Pliocene and early Pleistocene age. Characteristic directions of best least-squares fit for 73 samples suggest little or no overall rotation, despite the severe late Quaternary tectonic activity demonstrated by the intense deformation of these strata.

scholarly journals Evolution of Early Pleistocene fluvial systems in central Poland prior to the first ice sheet advance – a case study from the Bełchatów lignite mine

Geologos ◽  
2017 ◽  
Vol 23 (2) ◽  
pp. 89-107
Author(s):  
Jan Goździk ◽  
Tomasz Zieliński
Keyword(s):  
Current Knowledge ◽  
Ice Sheet ◽  
Grain Morphology ◽  
Field Studies ◽  
Early Pleistocene ◽  
Cold Desert ◽  
Fluvial Systems ◽  
Central Poland ◽  
Lignite Mine ◽  
Channel Patterns

AbstractDeposits formed between the Neogene/Pleistocene transition and into the Early Pleistocene have been studied, mainly on the basis of drillings and at rare, small outcrops in the lowland part of Polish territory. At the Bełchatów lignite mine (Kleszczów Graben, central Poland), one of the largest opencast pits in Europe, strata of this age have long been exposed in extensive outcrops. The present paper is based on our field studies and laboratory analyses, as well as on research data presented by other authors. For that reason, it can be seen as an overview of current knowledge of lowermost Pleistocene deposits at Bełchatów, where exploitation of the Quaternary overburden has just been completed. The results of cartographic work, sedimentological, mineralogical and palynological analyses as well as assessment of sand grain morphology have been considered. All of these studies have allowed the distinction of three Lower Pleistocene series, i.e., the Łękińsko, Faustynów and Krzaki series. These were laid down in fluvial environments between the end of the Pliocene up to the advance of the first Scandinavian ice sheet on central Poland. The following environmental features have been interpreted: phases of river incision and aggradation, changes of river channel patterns, source sediments for alluvia, rates of aeolian supply to rivers and roles of fluvial systems in morphological and geological development of the area. The two older series studied, i.e., Łękińsko and Faustynów, share common characteristics. They were formed by sinuous rivers in boreal forest and open forest environments. The Neogene substratum was the source of the alluvium. The younger series (Krzaki) formed mainly in a braided river setting, under conditions of progressive climatic cooling. Over time, a gradual increase of aeolian supply to the fluvial system can be noted; initially, silt and sand were laid down, followed by sand only during cold desert conditions. These fluvio-periglacial conditions are identified in the foreground of the advance of the oldest ice sheet into this part of central Poland. The series studied have been compared with other fluvial successions which accumulated in the Kleszczów Graben during subsequent glaciations so as to document general changes in fluvial systems as reactions to climatic evolution. Thus, a palaeoenvironmental scenario has emerged which could be considered to be characteristic of central Poland during the Early Pleistocene.

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