Effects of glacier meltwater on the algal sedimentary record of an alpine lake in the central US Rocky Mountains throughout the late Holocene

2015 ◽  
Vol 53 (4) ◽  
pp. 385-399 ◽  
Author(s):  
Krista E. H. Slemmons ◽  
Jasmine E. Saros ◽  
Jeffery R. Stone ◽  
Suzanne McGowan ◽  
C. T. Hess ◽  
...  
Keyword(s):  
Rocky Mountains ◽  
Late Holocene ◽  
Alpine Lake ◽  
Sedimentary Record ◽  
Glacier Meltwater

scholarly journals Detection of Large Holocene Earthquakes in the Sedimentary Record of Wellington, New Zealand, Using Diatom Analysis

2021 ◽  
Author(s):  
◽  
Ursula Alyson Cochran
Keyword(s):  
New Zealand ◽  
Late Holocene ◽  
Weighted Averaging ◽  
Diatom Analysis ◽  
Sedimentary Record ◽  
Sedimentary Sequences ◽  
Quantitative Estimates ◽  
Modern Analogue ◽  
Environmental Transitions ◽  
Large Earthquakes

<p>New Zealand is situated on the boundary between the Pacific and Australian tectonic plates. The Wellington region lies near the southern end of the Hikurangi subduction zone and within a zone of major, active strike-slip faults. Wellington's paleoseismic and historic records indicate that large surface rupture earthquakes have occurred on these faults in the past. Development of a complete record of past large earthquakes is a high priority for the region because of the risk posed by occurrence of large earthquakes in the future. The existing paleoseismic record has been derived predominantly from studies of fault trench stratigraphy, raised beach ridges and offset river terraces. The sedimentary record of lakes and coastal waterbodies is a source of information that has not been used specifically for paleoseismic purposes in the region. Therefore investigation of Wellington's sedimentary record is used in this thesis to make a contribution to the paleoseismic record. Holocene sedimentary sequences are studied from three small, low elevation, coastal waterbodies: Taupo Swamp, Okupe Lagoon and Lake Kohangapiripiri. Sequences of between 200 and 650 cm depth were collected using a hand-operated coring device. Sedimentology and diatom microfossil content were analysed and interpreted to enable reconstruction of paleoenvironment at each site. Radiocarbon dating was used to provide chronologies for the sequences that are aged between 5000 and 7500 calibrated years before present (cal. years BP). Diatom analysis is the main tool used to reconstruct paleoenvironment and detect evidence for occurrence of past large earthquakes. To aid reconstruction of sedimentary sequences used in this project, as well as coastal sequences in New Zealand in general, a coastal diatom calibration set was constructed using 50 sites around New Zealand. Modern diatom distribution and abundance, and associated environmental variables are analysed using ordination and weighted averaging techniques. Detrended correspondence analysis arranges species according to salinity preferences and divides sites clearly into waterbody types along a coastal gradient. This analysis enables reconstruction of waterbody type from fossil samples by passive placement onto ordination diagrams. Weighted averaging regression of calibration set samples results in a high correlation (r2jack=0.84) between observed and diatom inferred salinity, and enables salinity preferences and tolerances to be derived for 100 species. This confirms for the first time that species' preferences derived in the Northern Hemisphere are generally applicable to diatoms living in the coastal zone of New Zealand. Weighted averaging calibration and the modern analogue technique are used to generate quantitative estimates of paleosalinity for fossil samples. Paleoenvironmental reconstructions of Taupo Swamp, Okupe Lagoon and Lake Kohangapiripiri indicate that each waterbody has been isolated from the sea during the late Holocene. Isolation has been achieved through interplay of sediment accumulation causing growth of barrier beaches, and coseismic uplift. Ten distinct transitions between different paleoenvironments are recognised from the three sequences. These transitions involve changes in relative sea level or water table level often in association with catchment disturbance or marine influx events. All transitions occur suddenly and are laterally extensive and synchronous within each waterbody. Quantitative estimates of paleosalinity and waterbody type are used to differentiate between large and small magnitude changes in paleoenvironment. Five transitions involve large amounts of paleoenvironmental change and provide evidence for earthquakes occurring at approximately 5200, approximately 3200, and approximately 2300 cal. years BP. Five other transitions are consistent with the effects of large earthquakes occurring at approximately 6800, 2200, approximately 1000, approximately 500 cal. years BP and 1855 AD but do not provide independent evidence of the events. Environmental transitions at Lake Kohangapiripiri clarify the timing of rupture of the Wairarapa Fault by bracketing incompatible age estimates derived from two different sites on the fault. The oldest environmental transitions recognised at Taupo Swamp and Okupe Lagoon both occur at approximately 3200 cal. years BP indicating that western Wellington was uplifted at this time. Environmental transitions are recorded at all three study sites at approximately 2300 cal. years BP indicating that the entire western and central Wellington region experienced coseismic uplift at this time. Because of the distance between sites this apparent synchroneity implies that several faults in the region ruptured at a similar time. Investigation of sedimentary sequences contributes to the existing paleoseismic record by providing additional estimates of timing for past large earthquakes, enabling estimation of the areal extent of the effects of past earthquakes, and by highlighting periods of fault rupture activity in the late Holocene.</p>

Late Quaternary Glacial and Vegetation Changes, Little Cottonwood Canyon Area, Wasatch Mountains, Utah

1979 ◽  
Vol 12 (2) ◽  
pp. 254-270 ◽  
Author(s):  
David B. Madsen ◽  
Donald R. Currey
Keyword(s):  
Rocky Mountains ◽  
Late Holocene ◽  
Late Quaternary ◽  
Summer Temperature ◽  
Vegetation Changes ◽  
Glacial Geology ◽  
The Holocene ◽  
Wasatch Mountains ◽  
Relative Moisture

Glacial geology and 14C dating in the central Wasatch Mountains indicate: an early canyon-mouth glaciation (Dry Creek till), probably during isotope stage 6; on that till, a paleosol (Majestic Canyon soil) dated at about 26,000 yr B.P.; overriding that soil, a later canyon-mouth glaciation (Bells Canyon till) probably beginning prior to about 19,000 yr B.P.; a midcanyon deglacial pause (Hogum Fork till) prior to 12,300 yr B.P.; an upper-canyon deglacial pause (Devils Castle till) prior to 7500 yr B.P.; and late Holocene periglaciation. Pollen ratios from bog profiles in the mid to upper reaches of the canyon suggest that temperatures cooler than the Holocene average occurred until after about 8000 yr B.P. Warmer and dryer than average conditions were initiated about 8000 to 7500 yr B.P. During the later portion of this Altithermal period conditions became relatively warm and wet. Two subsequent episodes of cooler than average temperatures correspond chronologically to the initial stades of Neoglaciation elsewhere in the Rocky Mountains. However, there is no geomorphic evidence of corresponding glacial activity in the canyon area. Relative moisture during these two periods differs significantly, suggesting that Neoglacial conditions were controlled primarily by changes in summer temperature.

Orbital and solar forcing of shifts in Mid- to Late Holocene flood intensity from varved sediments of pre-alpine Lake Ammersee (southern Germany)

2013 ◽  
Vol 61 ◽  
pp. 96-110 ◽  
Author(s):  
Markus Czymzik ◽  
Achim Brauer ◽  
Peter Dulski ◽  
Birgit Plessen ◽  
Rudolf Naumann ◽  
...  
Keyword(s):  
Late Holocene ◽  
Alpine Lake ◽  
Solar Forcing ◽  
Southern Germany ◽  
Varved Sediments ◽  
Flood Intensity

Late Holocene solifluction lobe activity in the Mount Rae area, southern Canadian Rocky Mountains

1987 ◽  
Vol 24 (8) ◽  
pp. 1634-1642 ◽  
Author(s):  
Daniel J. Smith
Keyword(s):  
Residence Time ◽  
Mean Residence Time ◽  
Rocky Mountains ◽  
Late Holocene ◽  
The Other ◽  
Canadian Rocky Mountains ◽  
Mass Wasting ◽  
Canadian Rockies

Solifluction lobes are tongue-shaped accumulations of sediment resulting from localized periglacial mass wasting. Radiocarbon records from beneath two turf-banked lobes in the Mount Rae area of the southern Canadian Rockies indicate that solifluction processes have been continuously active for at least the last 2000 years. The long-term rates of frontal movement at both sites average 0.49 cm/year, but vary in magnitude from 0.35 to 1.50 cm/year.Both lobes terminate above soil pedons progressively overridden by their advance. Estimates of the apparent mean residence time of the contemporary soil ranges from 962 ± 100 years in one case to 1600 ± 100 years in the other. This information was used to reconstruct a chronology of lobe activity. Collectively, the radiocarbon records indicate that solifluction lobes in this area were advancing quite rapidly between 1900–1750 years BP but declined to a much slower, but relatively constant, pace up until the present.

Sedimentary record of late Holocene event beds in a mid-ocean atoll lagoon, Maldives, Indian Ocean: Potential for deposition by tsunamis

2014 ◽  
Vol 348 ◽  
pp. 37-43 ◽  
Author(s):  
Lars Klostermann ◽  
Eberhard Gischler ◽  
David Storz ◽  
J. Harold Hudson
Keyword(s):  
Indian Ocean ◽  
Late Holocene ◽  
Sedimentary Record ◽  
Atoll Lagoon

A late Holocene record of disturbance from the northern Rocky Mountains, USA

2013 ◽  
Vol 310 ◽  
pp. 245
Author(s):  
Jennifer H. Watt ◽  
Andrea Brunelle ◽  
Kurt Kipfmueller
Keyword(s):  
Rocky Mountains ◽  
Late Holocene ◽  
Northern Rocky Mountains ◽  
Holocene Record

Late Holocene glacier expansion in the Cariboo and northern Rocky Mountains, British Columbia, Canada

2012 ◽  
Vol 51 ◽  
pp. 71-80 ◽  
Author(s):  
Malyssa K. Maurer ◽  
Brian Menounos ◽  
Brian H. Luckman ◽  
Gerald Osborn ◽  
John J. Clague ◽  
...  
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Late Holocene ◽  
Northern Rocky Mountains

Seasonal Food Habits of Bull Trout from a Small Alpine Lake in the Canadian Rocky Mountains

1999 ◽  
Vol 128 (6) ◽  
pp. 1176-1192 ◽  
Author(s):  
Frank M. Wilhelm ◽  
Brian R. Parker ◽  
David W. Schindler ◽  
David B. Donald
Keyword(s):  
Rocky Mountains ◽  
Food Habits ◽  
Alpine Lake ◽  
Bull Trout ◽  
Canadian Rocky Mountains
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