THREE-DIMENSIONAL NETWORK OF CHROMITE CRYSTALS IN LAYERED INTRUSIONS AS EVIDENCE FOR SELF-NUCLEATION AND IN SITU GROWTH IN BASALTIC MAGMA CHAMBERS

AbstractAn understanding of magma chamber dynamics relies on answering three important yet highly controversial questions: where, why, and how magma chambers crystallize and differentiate. Here we report on a new natural phenomenon—the undercut-embayed chamber floor in the Bushveld Complex—which allows us to address these questions. The undercut-embayed floor is produced by magmatic karstification (i.e. erosion by dissolution) of the underlying cumulates by replenishing magmas that form basal flows on the chamber floor. This results in a few metres thick three-dimensional framework of spatially interconnected erosional remnants that separate the floor cumulates from the overlying resident melt. The basal flow in this environment is effectively cooled through the floor, inducing heterogeneous nucleation and in situ growth against much of its three-dimensional framework. The solidification front thus propagates in multiple directions from the surfaces of erosional remnants. Fractional crystallization may occur within this environment by convective removal of a compositional boundary layer from in situ growing crystals and is remarkably efficient even in very confined spaces. We propose that the way magma crystallizes and differentiates in the undercut-embayed chamber floor is likely common for the evolution of many basaltic magma chambers.

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A microscopic approach to investigate bacteria under in situ conditions in sea-ice samples

Annals of Glaciology ◽

10.3189/172756401781818275 ◽

2001 ◽

Vol 33 ◽

pp. 304-310 ◽

Cited By ~ 76

Author(s):

Karen Junge ◽

Christopher Krembs ◽

Jody Deming ◽

Aaron Stierle ◽

Hajo Eicken

Keyword(s):

Sea Ice ◽

Pore Space ◽

Three Dimensional ◽

Epifluorescence Microscopy ◽

Microbial Populations ◽

Microbial Life ◽

Dimensional Network ◽

In Situ Conditions ◽

Fluorescent Stain

AbstractMicrobial populations and activity within sea ice have been well described based on bulk measurements from melted sea-ice samples. However, melting destroys the micro-environments within the ice matrix and does not allow for examination of microbial populations at a spatial scale relevant to the organism. Here, we describe the development of a new method allowing for microscopic observations of bacteria localized within the three-dimensional network of brine inclusions in sea ice under in situ conditions. Conventional bacterial staining procedures, using the DNA-specific fluorescent stain DAPI, epifluorescence microscopy and image analysis, were adapted to examine bacteria and their associations with various surfaces within microtomed sections of sea ice at temperatures from −2° to −15°C. The utility and sensitivity of the method were demonstrated by analyzing artificial sea-ice preparations of decimal dilutions of a known bacterial culture. When applied to natural, particle-rich sea ice, the method allowed distinction between bacteria and particles at high magnification. At lower magnifications, observations of bacteria could be combined with those of other organisms and with morphology and particle content of the pore space. The method described here may ultimately aid in discerning constraints on microbial life at extremely low temperatures.

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In-Situ Formation and Coating of Cordierite Whiskers on Cordierite Based Honeycomb Support

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.317-318.701 ◽

2006 ◽

Vol 317-318 ◽

pp. 701-704

Author(s):

Daniel Doni Jayaseelan ◽

Shunkichi Ueno ◽

Hideki Kita ◽

Naoki Kondo ◽

Tatsuki Ohji

Keyword(s):

Three Dimensional ◽

Sem Analysis ◽

In Situ Method ◽

Dimensional Network ◽

In Situ Formation ◽

Cordierite Honeycomb ◽

Complete Formation ◽

Aqueous Slurry

In this work, cordierite whiskers were successfully coated on cordierite honeycomb support by in-situ method. Whisker coating was performed on walls of the pore channels of cordierite support from aqueous slurry. Sintering was carried out at 1300 °C for 4 hours. XRD measurements revealed a complete formation of cordierite phase, no traces of other phases were identified. A well adherence of coating on the support was identified from the microstructure. SEM analysis also revealed the formation of three-dimensional network of cordierite whiskers with open pores between them on the cordierite support.

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Intracellular Nonenzymatic In Situ Growth of Three-Dimensional DNA Nanostructures for Imaging Specific Biomolecules in Living Cells

ACS Nano ◽

10.1021/acsnano.9b09995 ◽

2020 ◽

Vol 14 (8) ◽

pp. 9572-9584

Author(s):

Ran Liu ◽

Songbai Zhang ◽

Ting-Ting Zheng ◽

Yan-Ru Chen ◽

Jing-Ting Wu ◽

...

Keyword(s):

Three Dimensional ◽

Living Cells ◽

In Situ Growth ◽

Dna Nanostructures

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Origin of non-cotectic cumulates: A novel approach

Geology ◽

10.1130/g47082.1 ◽

2020 ◽

Vol 48 (6) ◽

pp. 604-608 ◽

Cited By ~ 2

Author(s):

R.M. Latypov ◽

S.Yu. Chistyakova

Keyword(s):

Phase Equilibria ◽

Basaltic Magma ◽

Parental Magma ◽

Magma Chambers ◽

Mechanical Mixing ◽

Novel Approach ◽

In Situ Crystallization ◽

Mechanical Separation ◽

Novel Concept

Abstract Plutonic mafic complexes are composed of cumulates in which minerals mostly occur in cotectic proportions. This is consistent with a concept that basaltic magma chambers predominantly crystallize in situ from margins inward. However, cumulates with two (or more) minerals in proportions that are at odds with those expected from liquidus phase equilibria also locally occur in these complexes. Such non-cotectic cumulates are commonly attributed to either mechanical separation of minerals crystallizing from the same parental magma or mechanical mixing of minerals originating from different parental magmas. Here we introduce a novel concept that does not require any of these processes to produce non-cotectic cumulates. The model involves melts that start crystallizing upon their cooling, while ascending along feeder conduits from deep staging reservoirs toward the Earth’s surface. Depending on the degree of cooling, the melts become successively saturated in one, two, and more liquidus phases. Given that most crystals are kept in suspension, the resulting magmas would contain a cargo of equilibrium phenocrysts in notably non-cotectic proportions. The replenishment of basaltic chambers developing through in situ crystallization by such magmas is likely responsible for the occasional formation of non-cotectic cumulates in plutonic mafic complexes.

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