Layered intrusions and traffic jams

Bons, Paul D.; Baur, Albrecht; Elburg, Marlina; Lindhuber, Matthias J.; Marks, Michael A.W.; Соэсоо, Алвар; Walte, Nicolas P.

doi:10.1130/g36276.1

Cited by 20 publications

(16 citation statements)

References 28 publications

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“…One possibility to produce a melt dense enough for feldspar to float is to crystalize large amounts of light minerals (sodalite) during an early stage. As cooling of the magma continues, amphibole, eudialyte and feldspar start to crystallize and the sinking amphibole and eudialyte interfere with the bouyont feldspar causing "traffic jams" (Bons et al 2015). These crowding effects may result in amphibole-rich mats underlain by alkali feldspar-rich horizons (the later black and white layers).…”

Section: Crystal Mat Formation and The Origin Of The Layered Kakortokmentioning

confidence: 98%

“…A quantitative treatment of crowding effects and mat-forming processes in the lower layered kakortokites is given by Baur (2012) and Bons et al (2015) and fur- ther implies that (depending on melt viscosity and a number of other factors) the formation of a thick layer of low-density minerals (e.g., sodalite) above a rhythmically layered sequence is also possible. This raises the possibility that parts of the naujaites may have formed simultaneously to kakortokites (see Sect.…”

Section: Crystal Mat Formation and The Origin Of The Layered Kakortokmentioning

confidence: 99%

“…Preliminary numerical simulations (Baur 2012;Bons et al 2015 show that it is possible to produce an uppermost light layer (sodalite-dominated), followed downwards by a rhythmic layered sequence (rich in alkali feldspar, eudialyte and amphibole), which is underlain by an amphibole-dominated unit (potentially represented by the "slumped kakortokites"?) out of one magma volume.…”

Section: A Genetic Link Between Kakortokites and Naujaites?mentioning

confidence: 99%

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The Ilímaussaq Alkaline Complex, South Greenland

Marks

Markl

2015

Springer Geology

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The Ilímaussaq complex in South Greenland is a well-studied multiphase alkaline to peralkaline intrusion of Mesoproterozoic age. Most of the Ilímaussaq rocks are extremely enriched in alkalis, iron, halogens, high-field-strength elements (HFSE) and other rare elements, forming one of the most differentiated peralkaline rock suites known.The major factors causing the extreme differentiation trends are low oxygen fugacity and silica activity as well as very low water activity in the melts. These inhibit the early exsolution of aqueous NaCl-bearing fluids and facilitate the enrichment of alkalis and halogens in the melts, thereby increasing the solubility of HFSE. The unusually long crystallization interval of these rocks and the suspected continuous transition from melt to fluid results in extensive (auto)metasomatism and hydrothermal overprint. Primary mineral assemblages are therefore partially resorbed in most rock units and replaced by secondary minerals to various extents.The Ilímaussaq complex is a well-known example of magmatic layering in peralkaline plutonic rocks. Recent investigations of mineral chemical trends in the layered rocks permit better understanding of their formation. The mechanism of crystal mats formation in the cooling magma causing crowding effects during settling of the layering-forming minerals is believed to govern the formation of the Ilímaussaq layered sequence.Despite more than 100 years of research and hundreds of publications on Ilí-maussaq, important aspects on the origin of some Ilímaussaq rocks, the architecture and deep structure of the complex and the significance of hydrocarbons and bitumens present in the peralkaline rocks remain unclear. Thus, plenty of room for further studies on these unusual rocks exists and interdisciplinary research is needed to better understand the genesis of this unique magmatic complex.

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Section: Crystal Mat Formation and The Origin Of The Layered Kakortokmentioning

confidence: 98%

Section: Crystal Mat Formation and The Origin Of The Layered Kakortokmentioning

confidence: 99%

Section: A Genetic Link Between Kakortokites and Naujaites?mentioning

confidence: 99%

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The Ilímaussaq Alkaline Complex, South Greenland

Marks

Markl

2015

Springer Geology

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“…The term pyroclastic density current encompasses a wide range of flows from dilute surges to dense flows, block-andash flows, and pumice flows (Branney and Kokelaar, 2002;Sulpizio and Dellino, 2008). Such flows occur as a mixture of particles and gas that is emplaced as a gravity current which propagates down the slopes of a volcano and is related to, for example, collapse of a volcanic column or lava dome.…”

Section: Pyroclastic Density Currentsmentioning

confidence: 99%

“…Bons et al (2015) developed a simple one-dimensional model using the finite-difference method to simulate the vertical profile of the evolving crystal fraction of an initially liquid magma chamber. Based on equations that are analogous to the inviscid Burgers' equation (Burgers, 1974), their model applied the so-called "traffic jam theory", which has also been used to explain the spontaneous formation of traffic jams on a motorway, where cars interact and slow down due to locally dense traffic.…”

Section: Magma Chamber To Plutonmentioning

confidence: 99%

A review of laboratory and numerical modelling in volcanology

Kavanagh¹,

Engwell²,

Martin³

2018

Solid Earth

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Abstract. Modelling has been used in the study of volcanic systems for more than 100 years, building upon the approach first applied by Sir James Hall in 1815. Informed by observations of volcanological phenomena in nature, including eyewitness accounts of eruptions, geophysical or geodetic monitoring of active volcanoes, and geological analysis of ancient deposits, laboratory and numerical models have been used to describe and quantify volcanic and magmatic processes that span orders of magnitudes of time and space. We review the use of laboratory and numerical modelling in volcanological research, focussing on sub-surface and eruptive processes including the accretion and evolution of magma chambers, the propagation of sheet intrusions, the development of volcanic flows (lava flows, pyroclastic density currents, and lahars), volcanic plume formation, and ash dispersal.When first introduced into volcanology, laboratory experiments and numerical simulations marked a transition in approach from broadly qualitative to increasingly quantitative research. These methods are now widely used in volcanology to describe the physical and chemical behaviours that govern volcanic and magmatic systems. Creating simplified models of highly dynamical systems enables volcanologists to simulate and potentially predict the nature and impact of future eruptions. These tools have provided significant insights into many aspects of the volcanic plumbing system and eruptive processes. The largest scientific advances in volcanology have come from a multidisciplinary approach, applying developments in diverse fields such as engineering and computer science to study magmatic and volcanic phenomena. A global effort in the integration of laboratory and numerical volcano modelling is now required to tackle key problems in volcanology and points towards the importance of benchmarking exercises and the need for protocols to be developed so that models are routinely tested against "real world" data.

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Pearce Element Ratio Diagrams and Cumulate Rocks

Nicholls

2018

Handbook of Mathematical Geosciences

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While this chapter is about Pearce element ratios, I've included some personal reflections as this book is a 50th Anniversary project of the IAMG. Pearce element ratios, Felix Chayes and the Chayes medal, came together on September 11, 2001. As the recipient of the Chayes Medal, I was in Cancún, Mexico on that fateful date to deliver a talk on Pearce element ratios. Pearce element ratios are designed to model processes of fractionation and accumulation in igneous systems. They are frequently used to extract information from analyses of rocks formed from melts produced by fractionation-volcanic suites. Rock bodies formed from the fractionated crystals-the cumulate rocks-have received practically no attention. From the standard paradigm describing the formation of cumulate rocks, based on studies of the Skaergaard Intrusion, one expects a predicted pattern of data points on a Pearce element ratio diagram. Points derived from the mean compositions of the units in the cumulate body should fall up-slope from the point representing the initial melt composition on a diagram that accounts for the cumulate assemblage. Points derived from the compositions of the inferred residual melts present at the beginning of crystallization of a unit in the rock body should fall down-slope from the point representing the initial magma. The distance between a point on the line of a Pearce element ratio diagram and the point representing the initial magma composition depends on (1) the size of the aliquot that crystallized to form the rock unit and (2) the ratio of crystals to melt in the mush that solidified to form the rock unit. Patterns extracted from computer simulations compared to analogous data points from units of the Skaergaard Intrusion indicate that the crystal mushes that formed the units of the Marginal Border Series had a smaller ratio of trapped melt to crystals than did coeval mushes forming the Upper Border Series. Simulation patterns further indicate that the LZa and UZa units of the Layered Series formed from assemblages with larger ratios of melt to crystals than did the respective coeval units, LZa* and UZa*, of the Marginal Border Series.

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Layered intrusions and traffic jams

Cited by 20 publications

References 28 publications

The Ilímaussaq Alkaline Complex, South Greenland

The Ilímaussaq Alkaline Complex, South Greenland

A review of laboratory and numerical modelling in volcanology

Pearce Element Ratio Diagrams and Cumulate Rocks

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