Tag Archives: Sedimentation Saturday

Evaporites

If you evaporate a 1000m column of sea water only 1.5m of evaporites are produced. Given this, how would you account for the 2km thickness of Permian Zechstein deposits? In your answer make reference to the sequence of minerals you … Continue reading

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Oxygen Isotopes

How are oxygen isotopes used in the correlation of Quaternary sediments? Chemostratigraphy is using stable isotopes in determining stratigraphic ages. Isotopes are variations in the number of neutrons of a particular element. Some isotopes, like oxygen ¹⁶O and ¹⁸O, have … Continue reading

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Walther’s Law

With reference to Walther’s Law, describe how changes in sea level can change the vertical and lateral relationship of facies. Accommodation rate is when the subsidence of a depositional basin allows for the accumulation of more sediments. When the accommodation … Continue reading

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1929 Grand Banks, Newfoundland earthquake

Following an earthquake in 1929 in the Grand Banks area, south of Newfoundland, 12 Atlantic submarine cables were broken in at least 23 places over a period of 12 hours. The breaks occurred progressively in a southward direction. The times … Continue reading

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Weathering of Igneous Rocks

What physical processes contribute to the weathering of rock and why might you expect mafic igneous rocks to weather at a faster rate than felsic igneous rocks? Weathering is the physical disintegration and chemical decomposition of rocks into soil, loose … Continue reading

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Reefs

What is a reef? In your answer provide a definition, general diagnostic features and explain how the reef fauna and flora aid in the precipitation of calcium carbonate. Reefs are self-generated limestone deposits, created by the organisms living in them. … Continue reading

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Carbonate Classification

Compare and contrast the carbonate classification schemes of Folk and Dunham. Carbonate rocks are composed of allochems and orthochems. Allochems are the outside components, effectively grains that are the equivalent of clasts in sandstones. Orthochems are the inside components, the … Continue reading

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Sandstone Maturity

With reference to quartz arenites, feldspathic arenites and lithic arenites, explain what is meant by “sandstone maturity.” Mineralogy & Weathering Supracrustal rocks are those formed at the surface. Subcrustal rocks are those formed below the surface. Where minerals form impact … Continue reading

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Sedimentation Saturday: An Introduction

A Problem I’m usually a geophysicist, trying to figure out what’s down there while staying safely up there. For geophysicists, classification of rocks is by their physical properties. Is it conductive, resistive, magnetic, or opaque to all my methods? This … Continue reading

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