How the closure of paleo-Tethys and Tethys oceans controlled the early breakup of Pangaea

AbstractNinety-six mummified crabeater seals discovered at Seymour Island (Isla Marambio) are reported. Each specimen was georeferenced, photographed and assigned to five different taphonomic states. Previous work stated that seals at Seymour Island get stranded inland around the breeding season. However, it is not clear if the species breeds in this area. The abundance of crabeater seals and the ice condition along Admiralty Sound (Estrecho Bouchard) were obtained by aerial surveys during spring (2015–17). It appears that the species uses the strait as a passage to breeding grounds. Under heavy ice conditions, the seals become stranded in the middle section of this strait and wander inland through a valley that represents the mouth of an ephemeral stream that ends at the pack ice level. This situation was observed in 2014 and 2015 when recently dead seals were found, evidencing that this natural trap is still active. Nonetheless, in 2016 and 2017, during an early breakup of Admiralty Sound, the seals that remained in the area were more numerous than in 2015 but they did not get stranded inland. This early breakup may encourage the seals to breed there in the presence of open water areas with ice floes.

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Tricentennial trends in spring ice breakups in three rivers in northern Europe

10.5194/tc-2021-326 ◽

2021 ◽

Author(s):

Stefan Norrgård ◽

Samuli Helama

Keyword(s):

21St Century ◽

18Th Century ◽

Hydroelectric Power Plant ◽

Hydroelectric Power ◽

Ice Breakup ◽

Breakup Date ◽

Long Term Trends ◽

The Difference ◽

Early Breakup ◽

Three Rivers

Abstract. In Finland, ice breakup observations have been recorded for centuries for Aura River (1749–2020), Torne River (1693–2020) and Kokemäki River (1793–2020). The Kokemäki River is a newly revised, extended, and updated ice breakup series from Pori. The Spearman analysis shows that the correlation between Aura and Kokemäki rivers is strong, while the correlation between the two southern rivers (Aura and Kokemäki) and Torne River is weaker. The difference is attributed to the longitudinal distance between the rivers. Temperature correlations are strong for all three rivers and the long-term trends towards earlier breakups are statistically significant. Aura and Kokemäki rivers show considerable changes. Aura and Kokemäki river have had two respectively three years without a complete ice cover in the 21st century. These are the first non-freeze events in over 270 years of recorded observations. In Torne River, however, the earliest recorded breakup date has changed only marginally the last 100 years. Moreover, the earliest recorded breakup date in the 21st century occurred only five days earlier than the earliest breakup date in the 18th century. Kokemäki River did not escape the hydroelectric power plant boom in the mid-1900s, and this has speeded up the breakup process. A qualitative analysis shows that exceptionally late ice breakups occurred in all three rivers in 1807, 1810 and 1867. There are noticeable clusters of late events in the early 1800s in all three series, while an exceptionally early breakup event occurred in Aura and Kokemäki rivers in 1822.

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The Importance of Spring and Autumn Atmospheric Conditions for the Evaporation Regime of Lake Superior

Journal of Hydrometeorology ◽

10.1175/jhm-d-12-0170.1 ◽

2013 ◽

Vol 14 (5) ◽

pp. 1647-1658 ◽

Cited By ~ 39

Author(s):

C. Spence ◽

P. D. Blanken ◽

J. D. Lenters ◽

N. Hedstrom

Keyword(s):

Numerical Models ◽

Lake Superior ◽

Ice Cover ◽

Heat Fluxes ◽

Atmospheric Conditions ◽

Air Temperatures ◽

Synoptic Conditions ◽

Annual Evaporation ◽

Evaporative Flux ◽

Early Breakup

Abstract Feedbacks between ice extent and evaporation have long been suspected to be important for Lake Superior evaporation because it is during autumn and winter when latent heat fluxes are highest. Recent direct measurements of evaporation made at the Stannard Rock Lighthouse have provided new information on the physical controls on Lake Superior evaporation, in particular that evaporation can react within hours to days to a change in synoptic conditions. However, the large heat capacity of the lake creates a strong seasonal cycle of energy storage and release. There is a complex interaction among heat storage, evaporation, and ice cover that is highly dependent on atmospheric conditions in the spring and autumn “shoulder seasons.” Small changes in conditions in November and March caused by synoptic-scale events can have profound impacts on annual evaporation, the extent of ice cover, and the length of the ice-covered period. Early winter air temperatures in November and December dictate the nature of ice formation and much of the winter evaporative flux. Decreased ice cover, by itself, does not necessarily lead to enhanced annual evaporation losses. Rather, a combination of low ice cover and warm spring air temperatures, leading to an early breakup, can significantly lengthen the next evaporation season and cause greater cumulative water loss the subsequent year. The influence of individual synoptic events on annual evaporation is notable enough that the research community should ensure that their role is properly captured in numerical models to provide sound predictions of future Laurentian Great Lakes evaporation regimes.

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Deterioration of trembling aspen clones in the Great Lakes region

Canadian Journal of Forest Research ◽

10.1139/x81-073 ◽

1981 ◽

Vol 11 (3) ◽

pp. 530-537 ◽

Cited By ~ 34

Author(s):

W. J. Shields Jr. ◽

J. G. Bockheim

Keyword(s):

Soil Properties ◽

Basal Area ◽

Mean Annual Temperature ◽

Genotypic Differences ◽

Trembling Aspen ◽

Temperature Regimes ◽

Exchangeable Ca ◽

Similar Temperature ◽

The Difference ◽

Early Breakup

In order to test the hypothesis that the deterioration of trembling aspen (Populustremuloides Michx.) is related to variations in climate, soil properties, and genotype, 59 trembling aspen clones were sampled in Michigan, Wisconsin, Minnesota, and Ontario. A longevity index (LI) was calculated by taking the difference between predicted basal area from normal yield tables and measured basal area for each clone. Correlations of environmental variables with LI indicate that aspen longevity decreases with increasing mean annual temperature. Under similar temperature regimes, aspen growing on xeric sites and on sites low in exchangeable Ca are most susceptible to early breakup. Since there were negligible differences in soil properties between nine pairs of adjacent deteriorating and relatively well stocked clones, we hypothesize that, under similar environmental conditions, variation in the timing of deterioration may be due to genotypic differences between clones.

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Deciphering the Late Paleozoic–Cenozoic Tectonic History of the Inner Central Andes Forearc: An Update From the Salar de Punta Negra Basin of Northern Chile

Frontiers in Earth Science ◽

10.3389/feart.2021.790526 ◽

2022 ◽

Vol 9 ◽

Author(s):

Fernando Martínez ◽

Mauricio Parra ◽

Rodrigo Gonzalez ◽

Cristopher López ◽

Patiño Ana ◽

...

Keyword(s):

Seismic Data ◽

Tectonic Setting ◽

Upper Permian ◽

Late Paleozoic ◽

Rift System ◽

Northern Chile ◽

Basin Inversion ◽

Half Graben ◽

Intermontane Basins ◽

Early Breakup

We integrated new and existing geological, geochronological, thermochronological, and two-dimensional (2D) seismic data from the Salar de Punta Negra Basin to define the Late Paleozoic–Cenozoic tectonic evolution of the inner Andean forearc of northern Chile more precisely. Our results indicate that this region experienced early Late Paleozoic–Mesozoic crustal extension, creating several basement half-graben structures bounded by east- and west-dipping master faults. These extensional basins were filled by Upper Permian to Jurassic volcanic and sedimentary (continental and marine) syn-rift deposits. The genesis of these structures is related to the early breakup of the western Gondwana continent and the development of the large Tarapacá Basin in northern Chile and southern Perú. Subsequently, Late Cretaceous to Paleocene contraction occurred, which led to the tectonic inversion of the pre-existing rift system and the uplift of the Paleozoic–Mesozoic syn-rift deposits. Seismic data show that Upper Cretaceous and Paleocene synorogenic deposits accumulated along and over inversion anticlines, recording the initial contraction and marking the change from an extensional to a contractional tectonic setting. During the final episodes of basin inversion, crustal shortening was accommodated by the Eocene to recent basement reverse faulting accompanied by the rapid exhumation of basement pre-rift blocks, which served as the principal sources for the sediments that filled the pre-Andean basins during the Late Cenozoic. Finally, the exhumed basement pre-rift blocks and the reverse faults compartmentalized the contractional intermontane basins, which constitute the main low topographic relief of the inner forearc of northern Chile.

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Late Cretaceous to Paleogene sand provenance, deposition and tectonomagmatic development in the southern Møre Basin, Norway

10.5194/egusphere-egu2020-8117 ◽

2020 ◽

Author(s):

Hans Jørgen Kjøll ◽

Ivar Midtkandal ◽

Sverre Planke

Keyword(s):

Late Cretaceous ◽

Field Work ◽

Ne Atlantic ◽

Source To Sink ◽

Igneous Activity ◽

History Of ◽

Chemical History ◽

Early Breakup ◽

Sand Provenance ◽

Increased Activity

<p>Upper Cretaceous and Paleocene sandstone strata represent promising reservoirs along the NE Atlantic margins, including new discoveries in recent years that has spurred increased activity in the area. Exploration and seismic imaging is complicated by massive Paleocene magmatism related to late rifting and early breakup, forming voluminous sill and dyke complexes hosted in the sedimentary succession and extrusive complexes, such as volcanic edifices and lava flows along the margin. Such igneous activity may have played an important role in the thermal and chemical history of reservoir zones. Their diagenetic properties as well as their physical appearance is expected to have been altered by the intrusions, breaking predictive trends otherwise common for deep-marine sedimentary strata. A new understanding of the nature and implication of igneous processes and deposition of sediments, combined with new understanding of sand source-to-sink systems in the region, is thus important to better evaluate the prospectivity of the southern M&#248;re Basin. The focus of this project will therefore be to asses sand provenance and depositional systems in basins in this area by incorporating on shore field work with integrated borehole and seismic studies. The main goal is to develop a new understanding of deposition of sand fairways during the Late Cretaceous and Paleogene to better understand this part of the break-up history of the NE Atlantic.</p>

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Emperors on thin ice: three years of breeding failure at Halley Bay

Antarctic Science ◽

10.1017/s0954102019000099 ◽

2019 ◽

Vol 31 (3) ◽

pp. 133-138 ◽

Cited By ~ 15

Author(s):

Peter T. Fretwell ◽

Philip N. Trathan

Keyword(s):

Historical Record ◽

Future Climate Change ◽

Emperor Penguin ◽

Climate Change Scenarios ◽

Tenfold Increase ◽

Breeding Failure ◽

Penguin Colony ◽

Fast Ice ◽

Strong Winds ◽

Early Breakup

AbstractSatellite imagery is used to show that the world's second largest emperor penguin colony, at Halley Bay, has suffered three years of almost total breeding failure. Although, like all emperor colonies, there has been large inter-annual variability in the breeding success at this site, the prolonged period of failure is unprecedented in the historical record. The observed events followed the early breakup of the fast ice in the ice creeks that the birds habitually used for breeding. The initial breakup was associated with a particularly stormy period in September 2015, which corresponded with the strongest El Niño in over 60 years, strong winds, and a record low sea-ice year locally. Conditions have not recovered in the two years since. Meanwhile, during the same three-year period, the nearby Dawson-Lambton colony, 55 km to the south, has seen a more than tenfold increase in penguin numbers. The authors associate this with immigration from the birds previously breeding at Halley Bay. Studying this ‘tale of two cities’ provides valuable information relevant to modelling penguin movement under future climate change scenarios.

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