scholarly journals Episodic construction of the early Andean Cordillera unravelled by zircon petrochronology

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
José Joaquín Jara ◽  
Fernando Barra ◽  
Martin Reich ◽  
Mathieu Leisen ◽  
Rurik Romero ◽  
...  
Keyword(s):  
Continental Lithosphere ◽  
Complex Interplay ◽  
Continental Arcs ◽  
The Andes ◽  
Andean Cordillera ◽  
Continental Arc ◽  
The World ◽  
Oceanic Plates ◽  
Orogenic Belts ◽  
Continental Growth

AbstractThe subduction of oceanic plates beneath continental lithosphere is responsible for continental growth and recycling of oceanic crust, promoting the formation of Cordilleran arcs. However, the processes that control the evolution of these Cordilleran orogenic belts, particularly during their early stages of formation, have not been fully investigated. Here we use a multi-proxy geochemical approach, based on zircon petrochronology and whole-rock analyses, to assess the early evolution of the Andes, one of the most remarkable continental arcs in the world. Our results show that magmatism in the early Andean Cordillera occurred over a period of ~120 million years with six distinct plutonic episodes between 215 and 94 Ma. Each episode is the result of a complex interplay between mantle, crust, slab and sediment contributions that can be traced using zircon chemistry. Overall, the magmatism evolved in response to changes in the tectonic configuration, from transtensional/extensional conditions (215–145 Ma) to a transtensional regime (138–94 Ma). We conclude that an external (tectonic) forcing model with mantle-derived inputs is responsible for the episodic plutonism in this extensional continental arc. This study highlights the use of zircon petrochronology in assessing the multimillion-year crustal scale evolution of Cordilleran arcs.

scholarly journals Geographical variability of bacterial communities of cryoconite holes of Andean glaciers

2021 ◽  
Author(s):  
Francesca Pittino ◽  
Michael Seeger ◽  
Roberto Azzoni ◽  
Roberto Ambrosini ◽  
Andrea Franzetti
Keyword(s):  
Bacterial Communities ◽  
High Elevation ◽  
Glacier Surface ◽  
Organic Matter Production ◽  
The Andes ◽  
Matter Production ◽  
O2 Concentration ◽  
The World ◽  
Water Ph ◽  
Andean Glaciers

AbstractCryoconite holes, ponds full of melting water with a sediment on the bottom, are hotspot of biodiversity of glacier surface. They host a metabolically active bacterial community that is involved in different dynamics concerning glacier ecosystems. Indeed, they are responsible of organic matter production and with other microorganisms establish a real microecosystem. Cryoconite holes have been described in different areas of the world (e.g., Arctic, Antarctic, Alps, Himalaya), and with this study we will provide the first description of bacterial communities of cryoconite holes of the Andes in South America. We collected samples on three high elevation glaciers of the Andes (Iver, Iver East and Morado glaciers) and two Patagonian glaciers located at sea level (Exploradores glacier and Perito Moreno). Results show that the most abundant orders are Burkholderiales, Cytophagales, Sphingobacteriales, Actinomycetales, Pseudomonadales, Rhodospiarillales, Rhizobiales, Sphingomonadales and Bacteroidales, which have been reported on glaciers of other areas of the world, Bacterial communities change from one glacier to another and both water pH and O2 concentration affect bacterial communities composition.

Experiencing Religion

2021 ◽  
pp. 126-149
Author(s):  
Uta A. Balbier
Keyword(s):  
Complex Interplay ◽  
Community Of Faith ◽  
Transnational Community ◽  
The World ◽  
Altar Call

At each of Graham’s revival meetings a modern, lived, and transnational community of faith formed, connecting believers to past and future crusades. By following the audience to the meetings themselves, this chapter shows how they experienced the “modern” faith that had featured prominently in the contemporary religious debates discussed in Chapter 1. In the complex interplay between the sacred and the profane in the meetings’ orchestration, this faith became tangible. At the revival meetings, relationships formed within the audiences, and through practices such as singing and praying participants contributed to the charging of the spiritual atmosphere that finally climaxed in the altar call. Several aspects of the revival meetings—the presence of international guests, the awareness of prayers being said around the world for those in attendance, and the translation and accessibility of conversation narratives—enhanced the feeling in audiences that they were part of the transnational community of Billy Graham’s followers.

Status of Ordovician and Silurian Radiolarian Studies in North America

1995 ◽  
Vol 8 ◽  
pp. 19-30 ◽  
Author(s):  
P. J. Noble ◽  
J. C. Aitchison
Keyword(s):  
North America ◽  
Middle Devonian ◽  
Pacific Rim ◽  
The Pacific ◽  
The World ◽  
Radiolarian Biostratigraphy ◽  
Orogenic Belts

Polycystine radiolaria that produce siliceous tests are known to range from Cambrian to Holocene. They have proven to be enormously useful in providing age control for siliceous marine sequences of Middle Devonian and younger ages, particularly for cherts and shales that are commonly devoid of other biostratigraphically useful fossils. The utility of radiolarian biostratigraphy became widely recognized in the 1970s and 1980s when it was applied in dating deformed marine siliceous sequences in orogenic belts around the world, most notably in Cordilleran North America and other areas along the Pacific rim (e.g., Jones and Murchey, 1986; Aitchison and Murchey, 1992; Ichikawa et al., 1990).

A Yilgarn seed to the Pilbara Craton (Australia)? Evidence from inherited zircons

Geology ◽  
2019 ◽  
Vol 47 (11) ◽  
pp. 1098-1102 ◽  
Author(s):  
Andreas Petersson ◽  
Anthony I.S. Kemp ◽  
Martin J. Whitehouse
Keyword(s):  
Western Australia ◽  
Pivotal Role ◽  
Early Earth ◽  
Continental Lithosphere ◽  
Yilgarn Craton ◽  
Zircon Population ◽  
O Isotope ◽  
Continental Growth ◽  
Pilbara Craton

Abstract Knowledge of the age and compositional architecture of Archean cratonic lithosphere is critical for models of geodynamics and continental growth on early Earth, but can be difficult to unravel from the exposed geology. We report the occurrence of numerous >3.7 Ga zircon crystals in 3.45 Ga rhyolites of the eastern Pilbara Craton (Western Australia), which preserve evidence for an Eoarchean meta-igneous component in the deep Pilbara crust. This inherited zircon population shares similar and distinctive age and Hf-O isotope characteristics with the oldest gneissic components of the Yilgarn Craton ∼500 km farther south, suggesting a common ca. 3.75 Ga felsic crustal nucleus to these two Archean granite-greenstone terranes. We infer a pivotal role for such ‘seeds’ in facilitating the growth and persistence of Archean continental lithosphere.

First airborne gravity wave observations at the world’s hotspot in Southern Argentina

2020 ◽  
Author(s):  
Markus Rapp ◽  
Bernd Kaifler ◽  
Andreas Dörnbrack ◽  
Sonja Gisinger ◽  
Tyler Mixa ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Antarctic Peninsula ◽  
Wave Activity ◽  
Airborne Lidar ◽  
Tierra Del Fuego ◽  
Mountain Waves ◽  
The Andes ◽  
Chemistry Research ◽  
The World ◽  
The Antarctic

<p>The region around Southern Argentina and the Antarctic peninsula is known as the world’s strongest hotspot of stratospheric gravity wave activity. In this region, large tropospheric winds are perturbed by the orography of the Andes and the Antarctic peninsula resulting in the excitation of mountain waves which might propagate all the way up into the upper mesosphere when the polar night jet is intact. In addition, satellite observations also show large stratospheric wave activity in the region of the Drake passage, i.e., in between the Andes and the Antarctic peninsula, and along the corresponding latitudinal circle of 60°S. The origin of these waves is currently not entirely understood. Several hypotheses are currently being investigated, like for example the idea that the mountain waves that were originally excited over the Andes and the Antarctic peninsula propagate horizontally to 60°S and along the latitudinal circle. In order to investigate this and other hypotheses the German research aircraft HALO was deployed to Rio Grande, Tierra del Fuego, at the Southern Tip of Argentina in September and November 2019 in the frame of the SOUTHTRAC (Southern hemisphere Transport, Dynamics, and Chemistry) research mission. A total of 6 dedicated research flights with a typical length of 7000km were conducted to obtain gravity wave observations with the newly developed ALIMA (ALIMA=Airborne LIdar for Middle Atmosphere research)-instrument and the GLORIA (GLORIA=Gimballed Limb Observer for Radiance Imaging of the Atmosphere) limb sounder. While ALIMA measures temperatures and temperature perturbations in the altitude range from 20-90 km, GLORIA observations allow to characterize wave perturbations in temperatures and trace gas concentrations below flight level (<~14 km). This paper gives an overview of the mission objectives, the prevailing atmospheric conditions during the HALO deployment, and highlights some outstanding initial results of the gravity wave observations.</p>

Darwin the geologist in southern South America

2016 ◽  
Vol 35 (2) ◽  
pp. 303-345 ◽  
Author(s):  
Robert H. Dott ◽  
Ian W. D. Dalziel
Keyword(s):  
South America ◽  
Charles Darwin ◽  
Lateral Compression ◽  
Central Chile ◽  
Southern South America ◽  
The Andes ◽  
Andean Cordillera ◽  
Marine Terraces ◽  
Four Books ◽  
Geological Map

Charles Darwin was a reputable geologist before he achieved biological fame. Most of his geological research was accomplished in southern South America during the voyage of H.M.S. Beagle (1831–1836). Afterward he published four books and several articles about geology and coral atolls and became active in the Geological Society of London. We have followed Darwin's footsteps during our own researches and have been very impressed with his keen observations and inferences. He made some mistakes, however, such as appealing to iceberg rafting to explain erratic boulders and to inundations of the sea to carve valleys. Darwin prepared an important hand-colored geological map of southern South America, which for unknown reasons he did not publish. The distributions of seven map units are shown. These were described in his books wherein he also documented multiple elevated marine terraces on both coasts of South America. While exploring the Andean Cordillera in central Chile and Argentina, he discovered two fossil forests. Darwin developed a tectonic theory involving vertical uplift of the entire continent, which was greatest in the Andes where magma leaked up from a hypothetical subterranean sea of magma to form volcanoes and earthquakes. The theory had little impact and was soon eclipsed by theories involving lateral compression of strata. His and other contemporary theories suffered from a lack of knowledge about the earth's interior. Finally with modern plate tectonic theory involving intense lateral compression across the Andean Cordillera we can explain satisfactorily the geology so carefully documented by Darwin.

The Limits of Possibility: Rand McNally in American Culture, 1898-1929

2000 ◽  
pp. 7-26
Author(s):  
Susan Schulten
Keyword(s):  
United States ◽  
Twentieth Century ◽  
The United States ◽  
Large Share ◽  
Complex Interplay ◽  
History Of Cartography ◽  
The World ◽  
Commercial Market ◽  
History Of ◽  
The Subject

In the early twentieth century, Rand McNally held a large share of the commercial market for maps and atlases in the United States. How the company built its reputation as an American cartographic authority—by both accepting and resisting change—is the subject of this essay. Critical to the company’s success was its ability to design materials that reinforced American notions of how the world ought to appear, an indication that the history of cartography is governed not just by technological and scientific advances, but also by a complex interplay between mapmakers and consumers.

scholarly journals Reference values for oxygen saturation from sea level to the highest human habitation in the Andes in acclimatised persons

Thorax ◽  
2017 ◽  
Vol 73 (8) ◽  
pp. 776-778 ◽  
Author(s):  
Jose Rojas-Camayo ◽  
Christian Richard Mejia ◽  
David Callacondo ◽  
Jennifer A Dawson ◽  
Margarita Posso ◽  
...  
Keyword(s):  
Oxygen Saturation ◽  
Sea Level ◽  
Reference Range ◽  
Age Groups ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
The Andes ◽  
The World ◽  
Human Habitation

Oxygen saturation, measured by pulse oximetry (SpO2), is a vital clinical measure. Our descriptive, cross-sectional study describes SpO2 measurements from 6289 healthy subjects from age 1 to 80 years at 15 locations from sea level up to the highest permanent human habitation. Oxygen saturation measurements are illustrated as percentiles. As altitude increased, SpO2 decreased, especially at altitudes above 2500 m. The increase in altitude had a significant impact on SpO2 measurements for all age groups. Our data provide a reference range for expected SpO2 measurements in people from 1 to 80 years from sea level to the highest city in the world.

State by Proxy: Privatized Government in the Andes

2010 ◽  
Vol 52 (2) ◽  
pp. 319-350 ◽  
Author(s):  
Christopher Krupa
Keyword(s):  
Political Power ◽  
State Theory ◽  
The State ◽  
Political Systems ◽  
African Countries ◽  
World Today ◽  
The Andes ◽  
Administration Of Justice ◽  
The World ◽  
State Functions

Recent ethnographic work on the state has exposed a crack in one of the founding myths of modern political power. Despite the state's transcendental claim to wielding absolute, exclusive authority within national territory, scholars have shown that in much of the world there are, in fact, “too many actors competing to perform as state,” sites where various power blocs “are acting as the state and producing the same powerful effects” (Aretxaga 2003: 396, 398) Achille Mbembe (2001: 74), writing of the external fiscal controls imposed upon African countries during the late 1980s, has termed this a condition of “fractionated sovereignty”—the dispersal of official state functions among various non-state actors. There is, as Mbembe suggests, “nothing particularly African” about this situation (ibid.). Around the world, the power of various “shadow” organizations like arms dealers and paramilitary groups seems increasingly to depend upon their ability to out-perform the state in many of its definitive functions, from the provision of security and welfare to the collection of taxes and administration of justice (Nugent 1999; Nordstrom 2004; Hansen 2005). These observations present a serious challenge to conventional state theory. They force us to consider whether such conditions of fragmented, competitive statecraft might be better understood not as deviant exceptions to otherwise centralized political systems but, rather, as the way that government is actually experienced in much of the world today.

Closing remarks

1977 ◽  
Vol 199 (1134) ◽  
pp. 187-187
Keyword(s):  
World Bank ◽  
International Organizations ◽  
Rural Populations ◽  
Complex Interplay ◽  
The World Bank ◽  
The World ◽  
Intractable Problems ◽  
Voluntary Agencies

We have all learned much during these two days, as we have been taking a broader view of the complex interplay of health and economics and development in the rural populations of the world. We are now better able to appreciate the need for an informed multi-disciplinary approach to the multifactorial basis of ill-health and poverty. Just as friction generates heat, and the rubbing together of rough ferrous surfaces produces sparks, so we have seen here a display of multi-professional sparks that should ignite policies and people. And remember Augustine’s phrase. ‘One loving spirit sets another on fire’. We have seen the urgent need to work together if these intractable problems are to be solved. This cooperation will embrace the World Bank and governments; governments and voluntary agencies; international organizations with their flexibility and initiative, and executive bodies like ministries of health; the technical and the cultural; the indigenous and the imported.

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