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 Supplemental Material: Atmospheric dust flux in northeastern Gondwana during the peak of the late Paleozoic ice age

2020 ◽  
Author(s):  
Mehrdad Sardar Abadi ◽  
et al.
Keyword(s):  
Ice Age ◽  
Supplementary Information ◽  
Late Paleozoic ◽  
Atmospheric Dust ◽  
Dust Flux ◽  
Late Paleozoic Ice Age

Supplementary information and Figures S1–S10 and Tables S1 and S2.

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

2020 ◽  
Author(s):  
Mehrdad Sardar Abadi ◽  
et al.
Keyword(s):  
Ice Age ◽  
Supplementary Information ◽  
Late Paleozoic ◽  
Atmospheric Dust ◽  
Dust Flux ◽  
Late Paleozoic Ice Age

Supplementary information and Figures S1–S10 and Tables S1 and S2.

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 Carbonate collapse and the late Paleozoic ice age marine biodiversity crisis

Geology ◽  
2019 ◽  
Vol 48 (2) ◽  
pp. 118-122 ◽  
Author(s):  
Diego Balseiro ◽  
Matthew G. Powell
Keyword(s):  
Marine Invertebrates ◽  
Marine Invertebrate ◽  
Mechanistic Explanation ◽  
Ice Age ◽  
Late Paleozoic ◽  
Marine Biodiversity ◽  
Data Set ◽  
Biodiversity Crisis ◽  
Late Paleozoic Ice Age ◽  
Low Diversity

Abstract The late Paleozoic ice age (LPIA) was characterized by persistently low diversity of marine invertebrates following a second-order mass extinction. Here, we used a data set of North American (paleotropical) fossil occurrences of brachiopod, bivalve, and coral genera from the Paleobiology Database, combined with lithologic data from Macrostrat, to demonstrate that low diversity was caused by the collapse of carbonate environments during the LPIA. After dividing the data by lithology, low diversity was evident only in carbonate environments, whereas diversity within siliciclastic environments actually increased during the LPIA, after a brief decline in the Serpukhovian (late Mississippian). Diversity patterns closely matched respective changes in the volume of carbonate and siliciclastic rocks. The contrasting patterns observed in the two environments suggest that habitat loss was a direct cause of changes in diversity, because other factors, such as temperature, would have affected genera in both environments. A causal relationship is also supported by the finding that diversity remained high in carbonate refugia (carbonate beds within majority-siliciclastic formations) until the Bashkirian, postdating the onset of icehouse conditions by ∼8 m.y. Our results provide a unifying, mechanistic explanation for the distinctive characteristics of the biotic impact, including its disproportionate effect on the tropical marine invertebrate fauna, prolonged recovery from extinction, low macroevolutionary rates during the recovery interval, and regional differences in its expression.

SUBDUED ECOLOGICAL CONSEQUENCES OF THE LATE PALEOZOIC ICE AGE

2016 ◽  
Author(s):  
Matthew G. Powell ◽  
◽  
Ian-Michael Taylor-Benjamin
Keyword(s):  
Ice Age ◽  
Late Paleozoic ◽  
Ecological Consequences ◽  
Late Paleozoic Ice Age

CARBONIFEROUS HIGH PALEO-LATITUDE INVERTEBRATE PALEOECOLOGY OF PATAGONIA DURING THE LATE PALEOZOIC ICE AGE

2017 ◽  
Author(s):  
Kate M. Gigstad ◽  
◽  
Margaret L. Fraiser ◽  
John L. Isbell ◽  
Lydia T. Albright ◽  
...  
Keyword(s):  
Ice Age ◽  
Late Paleozoic ◽  
Late Paleozoic Ice Age
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