A record of dust deposition in northern, mid-latitude Pangaea during peak icehouse conditions of the late Paleozoic ice age

2020 ◽  
Vol 90 (4) ◽  
pp. 337-363
Author(s):  
Andrew J. Oordt ◽  
Gerilyn S. Soreghan ◽  
Lars Stemmerik ◽  
Linda A. Hinnov
Keyword(s):  
High Frequency ◽  
Prolonged Exposure ◽  
Fine Sand ◽  
Ice Age ◽  
Dust Deposition ◽  
Atmospheric Dust ◽  
Silicate Mineral ◽  
Subaerial Exposure ◽  
Dust Loading ◽  
Sequence Boundaries

ABSTRACT The Wordiekammen Formation, a carbonate ramp on Spitsbergen developed on the Northern Pangaean margin in Moscovian (Carboniferous) through Sakmarian (Permian) time at a paleolatitude of 30–35° N. The study site on the Nordfjorden High was isolated from any source of fluvio-deltaic input, such that detrital material that occurs in this system experienced eolian transport, thus forming a proxy for atmospheric dust loading. We analyzed two intervals, of Moscovian (10 m) and Asselian (27 m) age, at 20 cm resolution, and identified five mid-ramp subtidal facies organized in upwardly shallowing, high-frequency sequences 3–5 m thick. High-frequency sequence boundaries commonly exhibit signs of subaerial exposure (e.g., Microcodium) developed atop subtidal facies, recording glacioeustatic falls (glacial phases), although the Moscovian section has a severe karst overprint attributable to prolonged exposure on a paleohigh. Samples were processed to isolate the silicate-mineral fraction (SMF), which includes both detrital silicate material and authigenic silica mostly in the form of (fine-sand-size) doubly terminated quartz crystals. Detrital cores in these crystals, together with other evidence, indicate recrystallization from fine-grained (silt- and clay-size) dust. Analysis of the dust record demonstrates that the Asselian (peak icehouse) had a significantly higher atmospheric dust load than the Moscovian (moderate icehouse). In the Asselian interval, dust input varies commensurate with glacial–interglacial cyclicity. Highest dust contents correspond to transgressive facies immediately above sequence boundaries, indicating peak atmospheric dust loading at lowstand to incipient interglacial times. Provenance data from detrital-zircon and whole-rock geochemistry indicate two distinct source regions for the dust. Dust from the Moscovian and lower Asselian intervals reflects a continental island-arc signature consistent with sourcing from the basement of northeast Greenland. Dust from the upper Asselian interval is more consistent with recycling from Devonian and Carboniferous strata of the east Greenland Caledonides, likely deflated from fluvial systems draining this orogenic system, indicating an expansion of regions of eolian deflation.

scholarly journals Atmospheric dust flux in northeastern Gondwana during the peak of the late Paleozoic ice age

2020 ◽  
Author(s):  
Mehrdad Sardar Abadi ◽  
Gerilyn S. Soreghan ◽  
Linda Hinnov ◽  
Nicholas G. Heavens ◽  
James D. Gleason
Keyword(s):  
High Frequency ◽  
Ice Age ◽  
Grain Size Analysis ◽  
Geochemical Data ◽  
Late Paleozoic ◽  
Dust Deposition ◽  
Atmospheric Dust ◽  
Data Set ◽  
Dust Flux ◽  
Late Paleozoic Ice Age

The silicate mineral fraction of shallow marine carbonates archives dust contributions to the Central Persian Terranes along the northeastern margin of Gondwana (∼30ºS paleolatitude), enabling reconstruction of atmospheric dust loading and circulation for intervals of the late Paleozoic ice age. The Central Persian Terranes hosted cyclic deposition of warm water carbonates from middle Pennsylvanian to earliest Permian time, and our data set includes two ∼28 m sections from the Moscovian and Asselian sampled at 20 cm intervals. Bounding surfaces between successive cycles (high-frequency sequences) are recognized by either abrupt basinward shifts in facies or subtle exposure features; these high-frequency sequences range from 1 m to 5 m thick and are interpreted to record glacioeustatic variations. Time series analysis of the dust fraction through the studied interval supports the hypothesis of orbital forcing for the dust signal. The stratigraphic pattern of the dust flux indicates minimal flux during interglacial highstands (0.19−0.27 g/cm2/kyr) and peak flux during glacial lowstands (3.77−4.57 g/cm2/kyr) after accounting for hiatal time at sequence boundaries. Grain size analysis of the dust for all samples (n = 230) reveals modal sizes (volume-based) of 1−15 µm through the Moscovian interval and 10−75 µm through the Asselian interval. Dust deposition increased during glacial times relative to interglacial times by a factor of 16 to 19. Additionally, the Asselian interval exhibits higher dust flux overall relative to the Moscovian interval, which is interpreted to reflect the more extreme icehouse conditions of the Asselian. Variation in the dust content through the studied sections provides an indicator of temporal changes in atmospheric loading that varied at both glacial−interglacial and higher-frequency (<104 yr) scales. Geochemical data reveal that the Arabian−Nubian Shield and southwestern Pangaea (South America) are the most likely sources of dust deposition in the Central Persian Terranes, with sources shifting during different phases. Increased dust flux during glacials likely reflects multiple factors, including enhanced aridity in the source region, exposure of shelf regions, and potential changes in winds. However, the discrepancy in model reconstructions of the amplitude of glacial−interglacial dust variations indicates that increased production of dust sourced by dynamic glaciation played a large role in enhancing dust flux during glacial phases.

scholarly journals Combined impacts of current and future dust deposition and regional warming on Colorado River Basin snow dynamics and hydrology

2013 ◽  
Vol 17 (11) ◽  
pp. 4401-4413 ◽  
Author(s):  
J. S. Deems ◽  
T. H. Painter ◽  
J. J. Barsugli ◽  
J. Belnap ◽  
B. Udall
Keyword(s):  
River Basin ◽  
Radiative Forcing ◽  
Colorado River ◽  
Climate Forcing ◽  
Flow Volume ◽  
Prior Work ◽  
Climate Scenarios ◽  
Dust Deposition ◽  
Snow Albedo ◽  
Dust Loading

Abstract. The Colorado River provides water to 40 million people in seven western states and two countries and to 5.5 million irrigated acres. The river has long been overallocated. Climate models project runoff losses of 5–20% from the basin by mid-21st century due to human-induced climate change. Recent work has shown that decreased snow albedo from anthropogenic dust loading to the CO mountains shortens the duration of snow cover by several weeks relative to conditions prior to western expansion of the US in the mid-1800s, and advances peak runoff at Lees Ferry, Arizona, by an average of 3 weeks. Increases in evapotranspiration from earlier exposure of soils and germination of plants have been estimated to decrease annual runoff by more than 1.0 billion cubic meters, or ~5% of the annual average. This prior work was based on observed dust loadings during 2005–2008; however, 2009 and 2010 saw unprecedented levels of dust loading on snowpacks in the Upper Colorado River Basin (UCRB), being on the order of 5 times the 2005–2008 loading. Building on our prior work, we developed a new snow albedo decay parameterization based on observations in 2009/10 to mimic the radiative forcing of extreme dust deposition. We convolve low, moderate, and extreme dust/snow albedos with both historic climate forcing and two future climate scenarios via a delta method perturbation of historic records. Compared to moderate dust, extreme dust absorbs 2× to 4× the solar radiation, and shifts peak snowmelt an additional 3 weeks earlier to a total of 6 weeks earlier than pre-disturbance. The extreme dust scenario reduces annual flow volume an additional 1% (6% compared to pre-disturbance), a smaller difference than from low to moderate dust scenarios due to melt season shifting into a season of lower evaporative demand. The sensitivity of flow timing to dust radiative forcing of snow albedo is maintained under future climate scenarios, but the sensitivity of flow volume reductions decreases with increased climate forcing. These results have implications for water management and suggest that dust abatement efforts could be an important component of any climate adaptation strategies in the UCRB.

scholarly journals Holocene climate variability in the Winter Rainfall Zone of South Africa

2013 ◽  
Vol 9 (3) ◽  
pp. 2309-2356 ◽  
Author(s):  
S. Weldeab ◽  
J.-B. W. Stuut ◽  
R. R. Schneider ◽  
W. Siebel
Keyword(s):  
South Africa ◽  
Surface Water ◽  
Thermal State ◽  
Causal Link ◽  
Major Elements ◽  
Ice Age ◽  
Time Interval ◽  
Dust Deposition ◽  
Winter Rainfall ◽  
Phytoplankton Productivity

Abstract. We established a multi-proxy time series comprising analyses of major elements in bulk sediments, Sr and Nd isotopes and grain size of terrigenous fraction, and δ18O and δ13C in tests of Neogloboquadrina pachyderma (sinistral) from a marine sediment sequence recovered off the Orange River. The records reveal coherent patterns of variability that reflect changes in wind strength, precipitation over the river catchments, and upwelling of cold and nutrient-rich coastal waters off western South Africa. The wettest episode of the Holocene in the Winter Rainfall Zone (WRZ) of South Africa occurred during the "Little Ice Age" (700–100 yr BP). Wet phases were accompanied by strengthened coastal water upwellings, a decrease of Agulhas water leakage into the southern Atlantic, and a reduced dust incursion over Antarctica. A continuous aridification trend in the WRZ and a weakening of the southern Benguela Upwelling System (BUS) between 9000 and 5500 yr BP parallel with increase of dust deposition over Antarctica and an enhanced leakage of warm Agulhas water into the southeastern Atlantic. The temporal relationship between precipitation changes in the WRZ, the thermal state of the coastal surface water, and leakage of warm water in southern Atlantic, and variation of dust incursion over Antarctica suggests a causal link that most likely was related to latitudinal shifts of the Southern Hemisphere westerlies. Our results of the mid-Holocene time interval may serve as an analogue to a possible long-term consequence of the current and future southward shift of the westerlies that may result in a decline of rainfall over southwest Africa and a weakened upwelling with implication for phytoplankton productivity and fish stocks. Furthermore, warming of the coastal surface water as a result of warm Agulhas water incursion into the southern BUS may affect coastal fog formation that is critical as moisture source for the endemic flora of the Namaqualand.

The Glacial World

2012 ◽  
Author(s):  
Jan Zalasiewicz ◽  
Mark Williams
Keyword(s):  
Johann Wolfgang Von Goethe ◽  
Fine Sand ◽  
Ice Age ◽  
Central Germany ◽  
Sea Floor ◽  
Alpine Valley ◽  
Geological Past ◽  
Fine Clay ◽  
Natural Dam ◽  
George Iii

It is a scene of devastation, as far as the eye can see. Swathes of bleak landscape, with strewn boulders embedded in a sticky mass of sandy clay. Here and there are signs of a little more order—distinct spreads of gravel or patches of fine sand. Mostly, though, it looks as though every type of sediment, from fine clay to house-sized blocks, has simply been stirred together and spread across the land. Remove the crops and topsoil of gentle Leicestershire and Suffolk, or of central Germany or Kansas, and this is what lies beneath. Between the ordered sedimentary strata of the distant geological past and the ordered calm of the present is evidence of an only-just-elapsed catastrophe, and two centuries ago, when the science of the Earth was young, the naturalists of those days pondered on what it might mean. There were those like the young William Buckland, both Reader in mineralogy at Oxford and priest (he went on to become Dean of Westminster), who saw in it evidence of the biblical Deluge. Or Jean André de Luc, mentor to the wife of George III, who considered that the large blocks had been fired, like Roman ballista, from the mountains by some powerful but mysterious explosions. Or Sir James Hall, a savant of Edinburgh, who thought that the blocks had been carried into position by tsunamis, generated when large areas of sea floor (he supposed) suddenly popped up like blisters—he was clearly of an intellectually playful disposition. Or Leopold von Buch, who invoked catastrophic mudflows (one such, indeed, did take place in an Alpine valley, the Val de Bagnes, just after von Buch’s paper on this topic was published, when a natural dam burst, scattering mud and boulders far down the valley, and killing many people). But it was that extraordinary polymath, Johann Wolfgang von Goethe (a one-time Superintendent of Mines, if you please) who was among the first to sense what had been going on, when he associated the scattered blocks with a great expansion of the Alpine glaciers he was familiar with, and coined the term Eiszeit —the Ice Age.

scholarly journals Vertical and horizontal heterogeneity of atmospheric dust loading in northern Gale Crater, Mars

Icarus ◽  
2019 ◽  
Vol 329 ◽  
pp. 197-206 ◽  
Author(s):  
Casey A. Moore ◽  
John E. Moores ◽  
Claire E. Newman ◽  
Mark T. Lemmon ◽  
Scott D. Guzewich ◽  
...  
Keyword(s):  
Atmospheric Dust ◽  
Gale Crater ◽  
Horizontal Heterogeneity ◽  
Dust Loading

scholarly journals Coupled stratigraphic and U-Pb zircon age constraints on the late Paleozoic icehouse-to-greenhouse turnover in south-central Gondwana

Geology ◽  
2019 ◽  
Vol 47 (12) ◽  
pp. 1146-1150 ◽  
Author(s):  
Neil Patrick Griffis ◽  
Isabel Patricia Montañez ◽  
Roland Mundil ◽  
Jon Richey ◽  
John Isbell ◽  
...  
Keyword(s):  
Ice Age ◽  
Late Paleozoic ◽  
Karoo Basin ◽  
Base Level ◽  
South Central ◽  
Paraná Basin ◽  
Forcing Mechanisms ◽  
Sequence Boundaries ◽  
Parana Basin ◽  
Order Sequence

Abstract The demise of the Late Paleozoic Ice Age has been hypothesized as diachronous, occurring first in western South America and progressing eastward across Africa and culminating in Australia over an ∼60 m.y. period, suggesting tectonic forcing mechanisms that operate on time scales of 106 yr or longer. We test this diachronous deglaciation hypothesis for southwestern and south-central Gondwana with new single crystal U-Pb zircon chemical abrasion thermal ionizing mass spectrometry (CA-TIMS) ages from volcaniclastic deposits in the Paraná (Brazil) and Karoo (South Africa) Basins that span the terminal deglaciation through the early postglacial period. Intrabasinal stratigraphic correlations permitted by the new high-resolution radioisotope ages indicate that deglaciation across the S to SE Paraná Basin was synchronous, with glaciation constrained to the Carboniferous. Cross-basin correlation reveals two additional glacial-deglacial cycles in the Karoo Basin after the terminal deglaciation in the Paraná Basin. South African glaciations were penecontemporaneous (within U-Pb age uncertainties) with third-order sequence boundaries (i.e., inferred base-level falls) in the Paraná Basin. Synchroneity between early Permian glacial-deglacial events in southwestern to south-central Gondwana and pCO2 fluctuations suggest a primary CO2 control on ice thresholds. The occurrence of renewed glaciation in the Karoo Basin, after terminal deglaciation in the Paraná Basin, reflects the secondary influences of regional paleogeography, topography, and moisture sources.

scholarly journals ESD Ideas: Propagation of high-frequency forcing to ice age dynamics

2019 ◽  
Vol 10 (2) ◽  
pp. 257-260 ◽  
Author(s):  
Mikhail Y. Verbitsky ◽  
Michel Crucifix ◽  
Dmitry M. Volobuev
Keyword(s):  
Conservation Laws ◽  
High Frequency ◽  
Ice Sheet ◽  
Ice Age ◽  
Ice Flow ◽  
Age Dynamics ◽  
Nonlinear Character ◽  
Continuous Background ◽  
Ice Sheet Dynamics ◽  
Flow Conservation

Abstract. Palaeoclimate records display a continuous background of variability connecting centennial to 100 kyr periods. Hence, the dynamics at the centennial, millennial, and astronomical timescales should not be treated separately. Here, we show that the nonlinear character of ice sheet dynamics, which was derived naturally from the ice-flow conservation laws, provides the scaling constraints to explain the structure of the observed spectrum of variability.

Radiative forcing of climate by ice-age atmospheric dust

2003 ◽  
Vol 20 (2) ◽  
pp. 193-202 ◽  
Author(s):  
T. Claquin ◽  
C. Roelandt ◽  
K. Kohfeld ◽  
S. Harrison ◽  
I. Tegen ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Ice Age ◽  
Atmospheric Dust

Analysis of coastal-plain fluvial architecture and high-frequency stacking patterns in the Upper Cretaceous Masuk Formation, Utah, U.S.A.: Climate-driven cyclicity?

2020 ◽  
Vol 90 (10) ◽  
pp. 1265-1285
Author(s):  
Aaron M. Hess ◽  
Christopher R. Fielding
Keyword(s):  
Coastal Plain ◽  
High Frequency ◽  
Upper Cretaceous ◽  
Alternative Hypothesis ◽  
Water Discharge ◽  
Short Interval ◽  
Directed Dispersal ◽  
Composite Channel ◽  
Sequence Boundaries ◽  
Stacking Patterns

ABSTRACT Most sequence stratigraphic models are based on the premise that relative changes in sea level (RSL) control stacking patterns in continental-margin settings. An alternative hypothesis, however, is that upstream factors, notably variations in relative water discharge (RQW) or the ratio of water to sediment discharge can influence or control stratal stacking patterns in fluvial systems. Sequence boundaries of RQW-driven systems differ from those driven by base-level fluctuations in that: 1) the depth of incision increases updip, and 2) rates of erosion are spatially uniform, leading to the formation of widespread, planar sequence boundaries. This paper presents an architectural and stratigraphic analysis of the well-exposed Masuk Formation of the Henry Mountains Syncline in southern Utah, an Upper Cretaceous coastal-plain fluvial succession that is interpreted to have been influenced significantly by RQW. Six lithofacies are recognized, three (Facies 1–3) recording floodbasin, mire, and (in one short interval) estuarine environments, and three (Facies 4–6) record different kinds of channel fills on a coastal alluvial plain. Seven major composite channel bodies (Facies 4–6), separated by intervals of non-channel deposits (Facies 1–3), are recognized in the stratigraphic interval. Composite channel bodies display planar, sheet-like geometry and are laterally continuous to a significantly greater extent (> 10 km) than would be expected from purely autogenic channel-belt construction. Together, these intervals record a series of high-frequency sequences, formed along the western margin of the Western Interior Seaway. In each individual sequence is a repetitive facies succession from a basal chaotic sandstone with admixed mudrock and sandstone transitioning upward to a more organized cross-bedded and stratified sandstone. This is interpreted to record cyclical changes from a peaked (flashy) discharge regime to a more normal runoff regime. Paleoflow data indicate a dominance of transverse (eastward-directed) dispersal early in the accumulation of the Masuk Formation, shifting to a pattern of greater axial (northward) dispersal over time. The RQW signal is strong in the lower part of the formation, decreasing upward. This suggests that the relatively short-headed streams draining from the rising Sevier fold–thrust belt were strongly influenced by climatic cyclicity, whereas more distally sourced systems were not. This study provides new insights into the architecture and stacking patterns of coastal-plain fluvial successions, emphasizing the plausible role that climate can play in shaping alluvial architecture in the rock record.

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