A 5-km-thick reservoir with >380,000 km3 of magma within the ancient Earth's crust

2021 ◽  
Author(s):  
Rais Latypov ◽  
Sofya Chistyakova ◽  
Richard Hornsey ◽  
Gelu Costin ◽  
Mauritz van der Merwe
Keyword(s):  
Bushveld Complex ◽  
Earth’S Crust ◽  
Magma Chambers ◽  
Crystallization Sequence ◽  
Igneous Provinces ◽  
Research Concept ◽  
History Of ◽  
Mineral Compositions ◽  
Earth's Crust ◽  
Chamber Floor

Abstract Several recent studies have argued that large, long-lived and molten magma chambers1–10 may not occur in the shallow Earth’s crust11–23. Here we present, however, field-based observations from the Bushveld Complex24 that provide evidence to the contrary. In the eastern part of the complex, the magmatic layering was found to continuously drape across a ~4-km-high sloping step in the chamber floor. Such deposition of magmatic layering implies that the resident melt column was thicker than the stepped relief of the chamber floor. Prolonged internal differentiation within such a thick magma column is further supported by evolutionary trends in crystallization sequence and mineral compositions through the sequence. The resident melt column in the Bushveld chamber during this period is estimated to be >5-km-high in thickness and >380,000 km3 in volume. This amount of magma is three orders of magnitude larger than any known super-eruptions in the Earth’s history25 and is only comparable to the extrusive volumes of some of Earth’s large igneous provinces26. This suggests that super-large, entirely molten and long-lived magma chambers, at least occasionally, occur in the geological history of our planet. Therefore, the classical view of magma chambers as ‘big magma tanks’1–10 remains a viable research concept for some of Earth’s magmatic provinces.

The history of the Earth's crust [book review]

1969 ◽  
Vol 267 (7) ◽  
pp. 853-0
Author(s):  
B. C. Burchfiel
Keyword(s):  
Earth’S Crust ◽  
History Of ◽  
Earth's Crust

Modeling of convective heat-mass transfer in permeable parts of seismic focal zones of the Kamchatka region and associated volcanic arcs

2021 ◽  
Author(s):  
Yuri Perepechko ◽  
Konstantin Sorokin ◽  
Anna Mikheeva ◽  
Viktor Sharapov ◽  
Sherzad Imomnazarov
Keyword(s):  
Mass Transfer ◽  
Mantle Wedge ◽  
Earth’S Crust ◽  
Magma Chambers ◽  
Volcanic Arcs ◽  
Fluid Systems ◽  
The Pacific ◽  
Kamchatka Region ◽  
The Pacific Ocean ◽  
Earth's Crust

<p>The paper presents a non-isothermal model of hydrodynamic heating of lithospheric rocks above magma chambers in application to the seismic focal zone of the Kamchatka region and associated volcanic arcs. The effect of convective heating of mantle and crustal rocks on dynamics of metasomatic changes and convective melting was studied. In the existing models of ore-forming systems, fluid mass transfer is determined mainly by the retrograde boiling of magmas in meso-abyssal intrusive chambers. Analysis of the manifestations of deposits of the porphyry formation of the Pacific Ocean active margins shows the decisive participation in their formation of mantle-crust ore-igneous systems. The model of convective heat-mass transfer in fluid mantle-crust systems coupled with magma chambers is designed with the consideration of effects of interphase interaction in rocks of permeable zones above igneous fluid sources. Numerical simulation of the dynamics of fluid systems under the volcanoes of the frontal zone of Kamchatka shows altered ultramafic rocks in metasomatic zoning and the presence of facial changes in the mineral composition of wehrlitized rocks. In the mantle wedge of the northwestern margin of the Pacific Ocean, over which epicontinental volcanic arcs developed in the post-Miocene stage, there is possible combination of the products of different-time and different-level igneous systems in the same permeable "earth's crust-lithospheric mantle" transition zones. Assuming that the "cratonization" of volcanic sections of the continental Earth's crust follows the "metasomatic granitization" pattern, the initial element of which is the wehrlitization of mantle wedge ultramafic rocks, the processes of metasomatic fertilization of mantle wedge rocks were investigated using a flow-through multiple-reservoir reactor. In the seismically active regions of the Pacific transition lithosphere, specific conditions for heating of areas of increased permeability above mantle fluid sources should be recorded. Metasomatic columns in such fluid systems can describe the formation of at least three levels of convective melting of metasomatized mantle wedge substrates, as well as the formation of a region of high-temperature fluid change of mafic intrusion rocks in the Earth's crust. The work was financially supported by the Russian Foundation for Basic Research, grants No. 19-05-00788.</p>

STORIA DELLA TERRA E TEMPI GEOLOGICI IN UNO SCRITTO INEDITO DI GIOVANNI ARDUINO: LA «RISPOSTA ALLEGORICO-ROMANZESCA» A FERBER

Nuncius ◽  
1991 ◽  
Vol 6 (2) ◽  
pp. 171-188 ◽  
Author(s):  
EZIO VACCARI
Keyword(s):  
Nineteenth Century ◽  
Earth Science ◽  
Earth’S Crust ◽  
Crucial Aspect ◽  
History Of ◽  
Earth's Crust

Abstract<title> SUMMARY </title>The publication of Giovanni Arduino's Risposta allegorico-romanzesc<?CTRLerr type="1" mess="Doute sur la typo" ?>a to J. J. Ferber highlights an unpublished and crucial aspect of Arduino's geology. The concept of epoch, applied to the history of the changes undergone by the Earth's crust, is put forward well before Buffon's Epoques de la Nature. Moreover the reflections of Arduino open up a «third possibility» between the catastrophist and uniformitarian hypotheses. This goes beyond the rigid antithesis between «Neptunism» and «Plutonism», which constituded the conditioning element of the study of Earth Science in Europe around the end of the eighteenth and the beginning of the nineteenth century.

Old Shore Lines of Palestine

1937 ◽  
Vol 74 (2) ◽  
pp. 68-78 ◽  
Author(s):  
G. S. Blake
Keyword(s):  
Earth’S Crust ◽  
The South ◽  
History Of ◽  
Earth's Crust

The object of this article is to bring up to date the known history of the earth's crust in the south-east Levant.

Drawing sedimentary outcrops

2019 ◽  
pp. 141-168
Author(s):  
Matthew J. Genge
Keyword(s):  
Depositional Environment ◽  
Sedimentary Rocks ◽  
Sedimentary Facies ◽  
Worked Examples ◽  
Earth’S Crust ◽  
Sedimentary Structures ◽  
History Of ◽  
Earth's Crust ◽  
Life On Earth

Sedimentary rocks are the commonest rocks found on the surface of the Earth’s crust and record much of the history of both our planet and life on Earth. This chapter describes how to draw outcrops of sedimentary rocks in the field and the most important features of these rocks to record and describe. The stratigraphy and interpretation of sedimentary rocks is also considered in the chapter and includes a description of common sedimentary structures. The use of sedimentary facies in evaluation of depositional environment is introduced. Five worked examples of field sketches of sedimentary outcrops are given to illustrate how to make accurate and detailed observations of sediments. Examples include how to draw unconformities, sedimentary structures, lithologies, and graphic logs.

Solidification timescale for the Dufek Intrusion, Antarctica determined by U-Pb zircon ages

2020 ◽  
Author(s):  
Jill VanTongeren ◽  
Aidan Taylor ◽  
Blair Schoene
Keyword(s):  
Bushveld Complex ◽  
Lower Section ◽  
Magma Chambers ◽  
Skaergaard Intrusion ◽  
Mafic Intrusion ◽  
Three Samples ◽  
Two Samples ◽  
Mineral Compositions ◽  
Layered Mafic Intrusion ◽  
Stratigraphic Thickness

&lt;p&gt;The 8-9 km thick Dufek layered mafic intrusion of Antarctica was emplaced at approximately 182 Ma associated with the Ferrar dolerites and the breakup of the supercontinent Gondwana.&amp;#160; It is rivaled in thickness only by the Bushveld Complex of South Africa and shows a similar progression in mineral compositions all the way to the uppermost contact with an overlying granophyre layer.&amp;#160; This progression in mineral composition suggests that it crystallized from the bottom to the top and did not form an upper solidification front (a.k.a., Upper Border Series) typical of smaller intrusions such as the Skaergaard Intrusion.&amp;#160; Unlike the Bushveld Complex, however, the Dufek Intrusion is exposed in only two ~1.8 km thick sections: the lowermost Dufek Massif, and the uppermost Forrestal Range, which are separated from one another by a ~50km wide snowfield.&amp;#160; The remainder of the stratigraphy is inferred from geophysics, evolution of mineral compositions, and projection of the dip of the layering through the snowfield.&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; We obtained precise CA-ID-TIMS U-Pb zircon ages from samples from the Dufek Massif and Forrestal Range in order to determine the timescale of solidification of a large layered mafic intrusion.&amp;#160; What we found is surprising - zircons from the bottom of the intrusion record younger ages than those from the top of the intrusion.&amp;#160; Two samples from the Dufek Massif have zircon U-Pb ages of 182.441&amp;#177;0.048 Ma and 182.496&amp;#177;0.057 Ma; whereas three samples from the Forrestal Range have zircon U-Pb ages of 182.601&amp;#177;0.064 Ma, 182.660&amp;#177;0.10 Ma, 182.78&amp;#177;0.21 Ma.&amp;#160; Thus, the lower section of the Dufek Intrusion solidified approximately 160,000 years after the upper.&amp;#160; We explore two possibilities for this reverse-age stratigraphy, (1) that the ages reflect the solidification of interstitial melt in a single magma chamber cooling from the top down, or (2) that the Dufek Massif and Forrestal Range are two separate magma chambers that are not connected at depth.&amp;#160; Our results have implications for the stratigraphic thickness estimates of the Dufek Intrusion as well as the duration of magmatism associated with continental breakup.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals Chromitite layers require the existence of large, long-lived, and entirely molten magma chambers

2021 ◽  
Author(s):  
Rais Latypov ◽  
Sofya Chistyakova ◽  
Stephen Barnes ◽  
Belinda Godel ◽  
Gary Delaney ◽  
...  
Keyword(s):  
Grain Size ◽  
Bushveld Complex ◽  
Layered Intrusions ◽  
Magma Chambers ◽  
Magmatic Body ◽  
Lateral Extent ◽  
Relationship Of ◽  
The Relationship ◽  
3D Framework ◽  
Chamber Floor

Abstract An emerging and increasingly pervasive school of thought is that large, long-lived and largely molten magma chambers are transient to non-existent in Earth’s history1–13. These ideas attempt to supplant the classical paradigm of the ‘big magma tank’ chambers in which the melt differentiates, is replenished, and occasionally feeds the overlying volcanoes14–23. The stratiform chromitites in the Bushveld Complex – the largest magmatic body in the Earth’s crust24 – however, offers strong contest to this shifting concept. Several chromitites in this complex occur as layers up to 2 metres in thickness and more than 400 kilometres in lateral extent, implying that chromitite-forming events were chamber-wide phenomena24–27. Field relations and microtextural data, specifically the relationship of 3D coordination number and grain size, indicate that the chromitites grew as a 3D framework of touching chromite grains directly at the chamber floor from a melt saturated in chromite only28–30. Mass-balance estimates dictate that a 1 to 4 km thick column of this melt26,31,32 is required to form each of these chromitite layers. Therefore, an enormous volume of melt (>1,00,000 km3)24,25 must have been involved in the generation of all the Bushveld chromitite layers, with half of this melt being expelled from the magma chamber24,26. We therefore argue that the very existence of thick and laterally extensive chromitite layers in the Bushveld and other layered intrusions strongly buttress the classical paradigm of ‘big magma tank’ chambers.

scholarly journals II.—On Faults in Strata

1869 ◽  
Vol 6 (62) ◽  
pp. 341-347
Author(s):  
Henry B. Medlicott
Keyword(s):  
Structural Features ◽  
Earth’S Crust ◽  
Geological Survey ◽  
Rock Series ◽  
Experimental Field ◽  
History Of ◽  
The Subject ◽  
Earth's Crust

A Little time back there appeared in the Magazine, some short papers on the subject of faults, and on the nature of the conditions and the forces through which these important structural features may-have been produced. The points I would now bring to notice are more elementary; they refer to the evidence for faults; hence involving the principal data upon which the higher discussion of the phenomena must be based, and the same data very argely affect our attempted restoration and history of bygone phases of the earth's surface. Faults and flexures in stratified rocks are the leading features through which we interpret the disturbances that have affected the earth's crust; and any looseness in determining their existence, form and amount, must vitiate many of our inferences. No one but an experimental field geologist can appreciate the difficulty of such determinations, and understand how faults are particularly liable to elude observation. This circumstance accounts for, but does not justify, the arbitrary use of faults in interpreting sections. To call in question the evidence upon such a familiar subject implies, of course, dissatisfaction at the manner in which it is handled in practice. This I at once admit, and will proceed to explain. The criticism I have to make is no more than might oceur to one who had never left his study; but I would state that with me it has had a most practical origin: in the progress of the work of the Geological Survey of India, several great boundary faults have been proposed in connection with our main rock-series, and in some cases published descriptions have been already given; but both on the score of the in-sufficiency of the evidence brought forward, and after personal examination in the field, I am unable to admit that some of the features in question can, without very implicit qualifications, be brought within the received definitions of a fault.

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