Century to millennial-scale temperature variations for the last two thousand years indicated from glacial geologic records of Southern Alaska

Wiles, Gregory C.; Barclay, David J.; Calkin, Parker E.; Lowell, Thomas V.

doi:10.1016/j.gloplacha.2006.07.036

Cited by 83 publications

(90 citation statements)

References 40 publications

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“…Accumulation rates range from ~100 to 800 cm/kyr in the jumbo piston core, with highest sedimentation rates in the upper 600 cmbsf (~1,500 cal ybp), peaking in the 200 to 500 cmbsf interval (~800 to 1000 cal ybp) presumably associated with a neoglacial expansion of the South Alaskan glacial system (Wiles et al,2008;Barclay et al, 2013). Slope core EW0408-85JC spans 17,400 cal ybp (Figure 3), and documents the most recent deglaciation of the Northeast Pacific (Davies et al, 2011).…”

Section: Chronologymentioning

confidence: 99%

A 17,000 yr paleomagnetic secular variation record from the southeast Alaskan margin: Regional and global correlations

Walczak

Stoner

Mix

et al. 2017

Earth and Planetary Science Letters

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High-resolution sedimentary records from two cores from the Gulf of Alaska margin allow development of a ~17,400 year reconstruction of paleomagnetic secular variation informing on regional and global variability. General agreement between the two records on their independent chronologies confirms that local PSV is recorded, demonstrating that such archives, notwithstanding complexities due to variable sedimentary regimes, deposition rates, and diagenetic conditions, can provide meaningful information on the past changes of the geomagnetic field. Comparisons with other independently-dated sedimentary paleomagnetic records from the greater Northeast Pacific indicate largely coherent inclination records that can be used to produce a regional inclination anomaly stack (NEPSIAS) capturing the common signal over an area spanning >30° longitude and latitude from Alaska through Oregon to Hawaii. Comparison of NEPSIAS with high quality declination records from the northern North Atlantic show significant similarity. Negative (shallow) anomalies in NEPSIAS inclination are associated with eastward NNA declination while positive (steep) anomalies in NEPSIAS inclination are associated with NNA westward declinations. The directional records can be compared to regional geomagnetic intensity over the past ~3000 years in North America and back nearly 9000 years in the Euro/Mediterranean region, suggesting oscillations in the relative strength of the North American flux lobe and Euro/Mediterranean extension of the Siberian flux lobe. This implicates a long-lived organizing structure imposed on the geomagnetic field, perhaps controlled by lower mantle and/or inner core heterogeneities, and supports the potential for stratigraphic correlation of directional PSV as a dating tool throughout the Holocene and perhaps beyond.

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Section: Chronologymentioning

confidence: 99%

A 17,000 yr paleomagnetic secular variation record from the southeast Alaskan margin: Regional and global correlations

Walczak

Stoner

Mix

et al. 2017

Earth and Planetary Science Letters

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“…Again, using this modern rate of deposition as a constant for the late Holocene record, the unit I basal unconformity would underlie ∼4500 years of sediment. Using these sedimentation rates, we define the unit I unconformity base as consistent with the onset of rapid deposition following a 3.5-4.5 ka neoglacial pulse (e.g., Wiles et al, 2008;Barclay et al, 2009;Zander et al, 2013). We term this seismic boundary the neoglacial unconformity (NGU) and assume an onset of late Holocene deposition at 4 ka for unit I beneath eastern PWS. We define the unit II strata beneath unit I as early Holocene sediment that is typically less than a few hundred meters thick.…”

Section: Pws Seismic Stratigraphymentioning

confidence: 99%

Landslides and Megathrust Splay Faults Captured by the Late Holocene Sediment Record of Eastern Prince William Sound, Alaska

Finn¹,

Liberty²,

Haeussler³

et al. 2015

Bulletin of the Seismological Society of America

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We present new marine seismic-reflection profiles and bathymetric maps to characterize Holocene depositional patterns, submarine landslides, and active faults beneath eastern and central Prince William Sound (PWS), Alaska, which is the eastern rupture patch of the 1964 M w 9.2 earthquake. We show evidence that submarine landslides, many of which are likely earthquake triggered, repeatedly released along the southern margin of Orca Bay in eastern PWS. We document motion on reverse faults during the 1964 Great Alaska earthquake and estimate late Holocene slip rates for these growth faults, which splay from the subduction zone megathrust. Regional bathymetric lineations help define the faults that extend 40-70 km in length, some of which show slip rates as great as 3:75 mm=yr. We infer that faults mapped below eastern PWS connect to faults mapped beneath central PWS and possibly onto the Alaska mainland via an en echelon style of faulting. Moderate (M w > 4) upper-plate earthquakes since 1964 give rise to the possibility that these faults may rupture independently to potentially generate M w 7-8 earthquakes, and that these earthquakes could damage local infrastructure from ground shaking. Submarine landslides, regardless of the source of initiation, could generate local tsunamis to produce large run-ups along nearby shorelines. In a more general sense, the PWS area shows that faults that splay from the underlying plate boundary present proximal, perhaps independent seismic sources within the accretionary prism, creating a broad zone of potential surface rupture that can extend inland 150 km or more from subduction zone trenches.

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“…In forefields of mountain glaciers and perennial snow and ice patches, in most cases quite close to the tree line, exposure of megafossil tree remnants of different species spanning major parts of the Holocene is quite common (e.g., Nicolussi and Patzelt, 2000;Hormes et al, 2001;Schlüchter and Jörin, 2004;Koch et al, 2007;Benedict et al, 2008;Joerin et al, 2008;Wiles et al, 2008;Scapozza et al, 2010;Koehler and Smith, 2011;Nicolussi and Schlüchter, 2012). In the Swedish Scandes, reconnaissance surveys of these newly emerging habitats have highlighted a surprising plethora of debris wood currently being released from beneath receding perennial ice and snow bodies at unprecedented elevations high above the tree line (Kullman, 2004a;Öberg and Kullman, 2011a;Kullman and Öberg, 2012).…”

Section: Introductionmentioning

confidence: 99%

New Aspects of High-Mountain Palaeobiogeography: A Synthesis of Data from Forefields of Receding Glaciers and Ice Patches in the Tärna and Kebnekaise Mountains, Swedish Lapland

Kullman¹,

Öberg²

2015

ARCTIC

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ABSTRACT. Recent recession of high-mountain glacier ice and perennial snow and ice patches has exposed megafossil and macrofossil tree remnants and peat, offering a new source of Holocene high alpine vegetation history in the Scandes. Radiocarbon dates of 90 tree megafossils from Swedish Lapland, 29 of which had not previously been published, range from 11 980 to 1950 cal yr BP. During the interval 9500 -8500 cal yr BP, mountain birch (Betula pubescens ssp. czerepanovii) and Scots pine (Pinus sylvestris) grew 600 -700 m higher upslope than they do today, which is a new and remarkable discovery. Subsequently, tree density gradually declined at higher elevations, and as the tree line moved downslope, the ratio of Betula to Pinus increased. Tree growth ceased around 4500 cal yr BP, presumably in response to the return of perennial ice and snow. A short episode of resumed tree growth of Betula indicates conditions warmer than present around 2000 years ago. Between c. 8500 and 7300 cal yr BP, Picea abies, Larix sibirica, Populus tremula, Sorbus aucuparia and Alnus incana were subordinate species on a forest floor dominated by plant species characteristic of prealpine or subalpine woodlands. Growth of trees as much as 700 m higher upslope than today around 9500 cal yr BP implies that summer temperatures at that time may have been 3.0˚C warmer than today's temperatures (corrected for land uplift). This inferred temperature difference between the early Holocene and the present concurs with changes in the Earth's orbital parameters.Key words: glaciers; tree growth; megafossils; macrofossils; Holocene; radiocarbon dating; climate change; Swedish Scandes RÉSUMÉ. Le recul récent de la glace de glacier, de la neige pérenne et des bancs de glace en haute montagne a permis de découvrir des mégafossiles et des macrofossiles de restes d'arbres et de tourbe, ce qui offre une nouvelle source d'histoire de la végétation alpine des Scandes en haute altitude pendant l'Holocène. La datation au carbone 14 de 90 mégafossiles d'arbres en provenance de la Laponie suédoise, dont 29 n'avaient jamais fait l'objet d'une publication, donne des résultats variant de 11 980 à 1 950 années cal. BP. Au cours de l'intervalle allant de 9 500 à 8 500 années cal. BP, le bouleau de montagne (Betula pubescens ssp. czerepanovii) et le pin sylvestre (Pinus sylvestris) poussaient à une hauteur de 600 à 700 m plus élevée qu'aujourd'hui, ce qui représente une découverte à la fois nouvelle et remarquable. Subséquemment, la densité des arbres a diminué graduellement en haute altitude, et au fur et à mesure que la limite forestière s'est mise à descendre, le rapport entre Betula et Pinus s'est accru. La croissance des arbres a cessé vers 4 500 années cal. BP, probablement en raison du retour de la glace et de la neige pérennes. Un bref épisode de reprise de la croissance des arbres de Betula indique la présence de conditions plus chaudes qu'à présent il y a environ 2 000 ans. Entre 8 500 et 7 300 années cal. BP environ, Picea abies, Larix sibirica, Populus tremu...

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Century to millennial-scale temperature variations for the last two thousand years indicated from glacial geologic records of Southern Alaska

Cited by 83 publications

References 40 publications

A 17,000 yr paleomagnetic secular variation record from the southeast Alaskan margin: Regional and global correlations

A 17,000 yr paleomagnetic secular variation record from the southeast Alaskan margin: Regional and global correlations

Landslides and Megathrust Splay Faults Captured by the Late Holocene Sediment Record of Eastern Prince William Sound, Alaska

New Aspects of High-Mountain Palaeobiogeography: A Synthesis of Data from Forefields of Receding Glaciers and Ice Patches in the Tärna and Kebnekaise Mountains, Swedish Lapland

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