scholarly journals Evolution of the Earth’s atmosphere during Late Veneer accretion

2020 ◽  
Vol 499 (4) ◽  
pp. 5334-5362
Author(s):  
Catriona A Sinclair ◽  
Mark C Wyatt ◽  
Alessandro Morbidelli ◽  
David Nesvorný
Keyword(s):  
Terrestrial Planet ◽  
Hydrodynamic Simulations ◽  
Substantial Growth ◽  
Early Atmosphere ◽  
The Earth ◽  
Wide Range ◽  
History Of ◽  
Current Mass ◽  
Low Mass ◽  
Late Veneer

ABSTRACT Recent advances in our understanding of the dynamical history of the Solar system have altered the inferred bombardment history of the Earth during accretion of the Late Veneer, after the Moon-forming impact. We investigate how the bombardment by planetesimals left-over from the terrestrial planet region after terrestrial planet formation, as well as asteroids and comets, affects the evolution of Earth’s early atmosphere. We develop a new statistical code of stochastic bombardment for atmosphere evolution, combining prescriptions for atmosphere loss and volatile delivery derived from hydrodynamic simulations and theory with results from dynamical modelling of realistic populations of impactors. We find that for an initially Earth-like atmosphere, impacts cause moderate atmospheric erosion with stochastic delivery of large asteroids, giving substantial growth (× 10) in a few ${{\ \rm per\ cent}}$ of cases. The exact change in atmosphere mass is inherently stochastic and dependent on the dynamics of the left-over planetesimals. We also consider the dependence on unknowns including the impactor volatile content, finding that the atmosphere is typically completely stripped by especially dry left-over planetesimals ($\lt 0.02 ~ {{\ \rm per\ cent}}$ volatiles). Remarkably, for a wide range of initial atmosphere masses and compositions, the atmosphere converges towards similar final masses and compositions, i.e. initially low-mass atmospheres grow, whereas massive atmospheres deplete. While the final properties are sensitive to the assumed impactor properties, the resulting atmosphere mass is close to that of current Earth. The exception to this is that a large initial atmosphere cannot be eroded to the current mass unless the atmosphere was initially primordial in composition.

Isotopes as clues to the origin and earliest differentiation history of the Earth

2008 ◽  
Vol 366 (1883) ◽  
pp. 4129-4162 ◽  
Author(s):  
Stein B Jacobsen ◽  
Michael C Ranen ◽  
Michael I Petaev ◽  
John L Remo ◽  
Richard J O'Connell ◽  
...  
Keyword(s):  
Time Scale ◽  
Magma Ocean ◽  
Crust Formation ◽  
Early Atmosphere ◽  
The Earth ◽  
Metal Silicate ◽  
Deep Earth ◽  
History Of ◽  
Mean Time ◽  
Late Veneer

Measurable variations in 182 W/ 183 W, 142 Nd/ 144 Nd, 129 Xe/ 130 Xe and 136 Xe Pu / 130 Xe in the Earth and meteorites provide a record of accretion and formation of the core, early crust and atmosphere. These variations are due to the decay of the now extinct nuclides 182 Hf, 146 Sm, 129 I and 244 Pu. The l82 Hf– 182 W system is the best accretion and core-formation chronometer, which yields a mean time of Earth's formation of 10 Myr, and a total time scale of 30 Myr. New laser shock data at conditions comparable with those in the Earth's deep mantle subsequent to the giant Moon-forming impact suggest that metal–silicate equilibration was rapid enough for the Hf–W chronometer to reliably record this time scale. The coupled 146 Sm– 147 Sm chronometer is the best system for determining the initial silicate differentiation (magma ocean crystallization and proto-crust formation), which took place at ca 4.47 Ga or perhaps even earlier. The presence of a large 129 Xe excess in the deep Earth is consistent with a very early atmosphere formation (as early as 30 Myr); however, the interpretation is complicated by the fact that most of the atmospheric Xe may be from a volatile-rich late veneer.

Computers in Geology - 25 Years of Progress

1994 ◽  
Keyword(s):  
Computer Modeling ◽  
Quantitative Methods ◽  
State Of The Art ◽  
International Association ◽  
Mathematical Geology ◽  
25Th Anniversary ◽  
The Earth ◽  
Wide Range ◽  
History Of ◽  
Mapping Techniques

This volume vividly demonstrates the importance and increasing breadth of quantitative methods in the earth sciences. With contributions from an international cast of leading practitioners, chapters cover a wide range of state-of-the-art methods and applications, including computer modeling and mapping techniques. Many chapters also contain reviews and extensive bibliographies which serve to make this an invaluable introduction to the entire field. In addition to its detailed presentations, the book includes chapters on the history of geomathematics and on R.G.V. Eigen, the "father" of mathematical geology. Written to commemorate the 25th anniversary of the International Association for Mathematical Geology, the book will be sought after by both practitioners and researchers in all branches of geology.

scholarly journals In-Situ Cosmogenic 14C: Production and Examples of its Unique Applications in Studies of Terrestrial and Extraterrestrial Processes

Radiocarbon ◽  
2001 ◽  
Vol 43 (2B) ◽  
pp. 731-742 ◽  
Author(s):  
D Lal ◽  
A J T Jull
Keyword(s):  
Half Life ◽  
Earth Science ◽  
Chemical Properties ◽  
Radioactive Isotopes ◽  
Earth’S Atmosphere ◽  
The Earth ◽  
Wide Range ◽  
History Of ◽  
Earth's Atmosphere

Nuclear interactions of cosmic rays produce a number of stable and radioactive isotopes on the earth (Lai and Peters 1967). Two of these, 14C and 10Be, find applications as tracers in a wide variety of earth science problems by virtue of their special combination of attributes: 1) their source functions, 2) their half-lives, and 3) their chemical properties. The radioisotope, 14C (half-life = 5730 yr) produced in the earth's atmosphere was the first to be discovered (Anderson et al. 1947; Libby 1952). The next longer-lived isotope, also produced in the earth's atmosphere, 10Be (half-life = 1.5 myr) was discovered independently by two groups within a decade (Arnold 1956; Goel et al. 1957; Lal 1991a). Both the isotopes are produced efficiently in the earth's atmosphere, and also in solids on the earth's surface. Independently and jointly they serve as useful tracers for characterizing the evolutionary history of a wide range of materials and artifacts. Here, we specifically focus on the production of 14C in terrestrial solids, designated as in-situ-produced 14C (to differentiate it from atmospheric 14C, initially produced in the atmosphere). We also illustrate the application to several earth science problems. This is a relatively new area of investigations, using 14C as a tracer, which was made possible by the development of accelerator mass spectrometry (AMS). The availability of the in-situ 14C variety has enormously enhanced the overall scope of 14C as a tracer (singly or together with in-situ-produced 10Be), which eminently qualifies it as a unique tracer for studying earth sciences.

Partitioning experiments in the laser-heated diamond anvil cell: volatile content in the Earth's core

2008 ◽  
Vol 366 (1883) ◽  
pp. 4295-4314 ◽  
Author(s):  
Andrew P Jephcoat ◽  
M. Ali Bouhifd ◽  
Don Porcelli
Keyword(s):  
Trace Elements ◽  
Diamond Anvil Cell ◽  
The Core ◽  
The Earth ◽  
Wide Range ◽  
Recent Developments ◽  
Mantle Reservoir ◽  
History Of ◽  
Diamond Anvil ◽  
Laser Heated

The present state of the Earth evolved from energetic events that were determined early in the history of the Solar System. A key process in reconciling this state and the observable mantle composition with models of the original formation relies on understanding the planetary processing that has taken place over the past 4.5 Ga. Planetary size plays a key role and ultimately determines the pressure and temperature conditions at which the materials of the early solar nebular segregated. We summarize recent developments with the laser-heated diamond anvil cell that have made possible extension of the conventional pressure limit for partitioning experiments as well as the study of volatile trace elements. In particular, we discuss liquid–liquid, metal–silicate (M–Sil) partitioning results for several elements in a synthetic chondritic mixture, spanning a wide range of atomic number—helium to iodine. We examine the role of the core as a possible host of both siderophile and trace elements and the implications that early segregation processes at deep magma ocean conditions have for current mantle signatures, both compositional and isotopic. The results provide some of the first experimental evidence that the core is the obvious replacement for the long-sought, deep mantle reservoir. If so, they also indicate the need to understand the detailed nature and scale of core–mantle exchange processes, from atomic to macroscopic, throughout the age of the Earth to the present day.

scholarly journals Leibniz and geography: geologist, paleontologist, biologist, historian, political theorist and geopolitician

2013 ◽  
Vol 68 (2) ◽  
pp. 81-93 ◽  
Author(s):  
S. Elden
Keyword(s):  
Middle Ages ◽  
Louis Xiv ◽  
Political Theorist ◽  
The Earth ◽  
Wide Range ◽  
German Philosopher ◽  
History Of ◽  
The Middle Ages ◽  
The Way

Abstract. This article discusses the way that the German philosopher and mathematician Gottfried Leibniz (1646–1716) made a number of significant contributions to geography. In outlining his contributions as a geologist, palaeontologist, biologist, historian, political theorist and geopolitician, it challenges the straightforward way he is read in geography. Particular focus is on his Protogaea, the Annales Imperii and the Consilium Aegyptiacum, respectively a pre-history of the earth, a chronology of German nobility in the Middle Ages, and a military-strategic proposal to King Louis XIV. Making use of contemporary debates about ways of reading Leibniz, and drawing on a wide range of his writings, the article indicates just how much remains to be discovered about his work.

Contributions of Volatiles to the Venus Atmosphere from the Observed Extrusive Volcanic Record: Implications for the History of the Venus Atmosphere

2021 ◽  
Author(s):  
James Head ◽  
Lionel Wilson ◽  
Mikhail Ivanov ◽  
Robin Wordsworth
Keyword(s):  
Atmospheric Pressure ◽  
Volcanic Eruptions ◽  
Planetary Science ◽  
Wide Range ◽  
History Of ◽  
Magma Compositions ◽  
Current Mass ◽  
Geologic Record ◽  
Limit Estimate ◽  
Venus Atmosphere

<p>One of the most important questions in planetary science is the origin of the current Venus atmosphere, its relationship and coupling to Venus’ geologic and geodynamic evolution, andwhy it is so different from that of the Earth. We specifically address the following question:Does the eruption of the total volume of extrusive volcanic deposits observed in the exposed geologic record of Venus contribute significantly to the current atmosphere through volatile release during emplacement of the extruded lavas? To address this question, we used the observed geologic and stratigraphic record of volcanic units and features, and their volumes, as revealed by Magellan (1; their Fig. 26 and Table 5).  We converted the volumes of the main volcanic units to lava/magma masses using a density of 3000 kg m<sup>-3</sup>. Next, we chose the upperthickness values, and added the contributions from allof the units; summing the values of the "total eruptives" gives the absolute upper limit estimate of the mass of documented volcanics that could contribute to the atmosphere, 7.335 x 10<sup>20 </sup>kg. We then compare this with the current mass of the Venus atmosphere (4.8 x 10<sup>20 </sup>kg). We find that in order to make the current atmosphere from the above volcanics, the magma would have to consist of 65.4% by mass volatiles, which is, of course, impossible. We conclude that the grand totalof the currently documented volcanics can not have produced other than a very small fraction of the current atmosphere.</p><p>Exsolution of volatiles during volcanic eruptions is significantly dependent on surface atmospheric pressure (2-3). However, the total volumeof lava erupted in the period of global volcanic resurfacingis still insufficient to produce the CO<sub>2</sub>atmosphere observed today, even if the ambient atmospheric pressure at that time was only 50% of what it is today. Therefore, a very significant part of the current CO<sub>2</sub>atmosphere must have been inherited from a time prior to the observed geologic record, sometime in the first ~80% of Venus history. Furthermore, the total volumeof lava erupted in the stratigraphically youngest period of the observed record (1) is insufficient to account for the current abundance of SO<sub>2 </sub>in the atmosphere; thus, it seems highly unlikely that current and recently ongoing volcanism could be maintaining the currently observed ‘elevated’ levels of SO<sub>2 </sub>in the atmosphere (4).  In addition, because of the fundamental effect of atmospheric pressure on the quantity of volatiles that will be degassed, varying the nature of the mantle melts over a wide range of magma compositions and mantle fO<sub>2 </sub>appears to have minimal influence on the outcome.  We conclude that the current Venus atmosphere must be a “fossil atmosphere”, largely inherited from a previous epoch in Venus history, and if so, may provide significant insight into the conditions during the first 80% of Venus history.</p><p>(1) Ivanov and Head (2013) Plan. Space Sci. 84, 66; (2) Gaillard & Scaillet, 2014, EPSL 403, 307; (3) Head & Wilson, 1986, JGR 91, 9407;(4)Esposito, 1984, Science 223, 1072.</p>

scholarly journals Internet Portal "Earth History: Geological Perspective". High-Technology Popularization of Scientific Geological Knowledge

2021 ◽  
Vol 24 (4) ◽  
pp. 604-621
Author(s):  
Aleksandr Sergeevich Eremenko ◽  
Vera Viktorovna Naumova ◽  
Aleksey Andreevich Zagumennov ◽  
Vitaliy Sergeevich Eremenko ◽  
Anastasia Nikolaevna Zlobina
Keyword(s):  
High Technology ◽  
Popular Science ◽  
High Tech ◽  
Multimedia Content ◽  
Internet Resource ◽  
Internet Portal ◽  
The Earth ◽  
Internet Users ◽  
Wide Range ◽  
History Of

This work is related to the development of a high-tech popular science Internet portal "History of the Earth". The developed resource sets as its main goal the popularization of modern scientific geological knowledge using popular science multimedia content and software tools for interactive work with it. The Internet resource is intended for schoolchildren and students, as well as a wide range of Internet users.

Isotopes

2016 ◽  
Author(s):  
Rob Ellam
Keyword(s):  
Solar System ◽  
Nuclear Power ◽  
Chemical Element ◽  
Radioactive Isotopes ◽  
Variant Form ◽  
Short Introduction ◽  
Carbon Dating ◽  
The Earth ◽  
Wide Range ◽  
History Of

An isotope is a variant form of a chemical element, containing a different number of neutrons in its nucleus. Most elements exist as several isotopes. Many are stable, others are radioactive, and some may only exist fleetingly before decaying into other elements. The study of isotope ratios has become central to many areas of science, and used to probe the age and history of the Earth and the origins of the Solar System. Radioactive isotopes find wide applications, from nuclear power to medicine and carbon dating. Isotopes: A Very Short Introduction provides an overview of the nature of stable and radioactive isotopes, considering their wide range of modern applications.

scholarly journals Extreme close encounters between proto-Mercury and proto-Venus in terrestrial planet formation

2020 ◽  
Vol 496 (3) ◽  
pp. 3781-3785
Author(s):  
Tong Fang ◽  
Hongping Deng
Keyword(s):  
Angular Momentum ◽  
Mass Fraction ◽  
Planet Formation ◽  
Orbital Motion ◽  
Terrestrial Planet ◽  
Small Mass ◽  
Tidal Dissipation ◽  
Hydrodynamic Simulations ◽  
Close Encounters ◽  
The Earth

ABSTRACT Modern models of terrestrial planet formation require solids depletion interior to 0.5–0.7 au in the planetesimal disc to explain the small mass of Mercury. The Earth and Venus analogues emerge after ∼100 Myr collisional growth, while Mercury forms in the diffusive tails of the planetesimal disc. We carried out 250 N-body simulations of planetesimal discs with mass confined to 0.7–1.0 au to study the statistics of close encounters that were recently proposed as an explanation for the high iron mass fraction in Mercury. We formed 39 Mercury analogues in total and all proto-Mercury analogues were scattered inwards by proto-Venus. Proto-Mercury typically experiences six extreme close encounters (closest approach smaller than six Venus radii) with Proto-Venus after Proto-Venus acquires 0.7 Venus Mass. At such close separation, the tidal interaction can already affect the orbital motion significantly such that the N-body treatment itself is invalid. More and closer encounters are expected should tidal dissipation of orbital angular momentum accounted. Hybrid N-body hydrodynamic simulations, treating orbital and encounter dynamics self-consistently, are desirable to evaluate the degree of tidal mantle stripping of proto-Mercury.

The Design of a Small Satellite for Earth Observation

1996 ◽  
Vol 210 (4) ◽  
pp. 323-332 ◽  
Author(s):  
S J Gardner ◽  
G G Swinerd ◽  
A K Ward
Keyword(s):  
Low Cost ◽  
Earth Observation ◽  
Low Earth Orbit ◽  
Small Satellite ◽  
Satellite Design ◽  
The Earth ◽  
Wide Range ◽  
Low Mass ◽  
Available Technology ◽  
Selection Of

The concept of the Teaching Company Scheme Satellite (TuCSAT), has been developed to meet the requirements of the Earth observation user community for inexpensive and flexible opportunities to launch remote sensing instruments into low earth orbit (LEO). This paper describes the satellite design process, together with the philosophy behind the selection of a baseline mission. The satellite is shown to demonstrate the ability to meet a wide range of requirements within a strict low mass and low cost philosophy, while making use of currently available technology in order to achieve the design aims.

Sign in / Sign up

Export Citation Format

Share Document