オブシディアンの水分化は,氷河積載の時期をさかのぼります

I Friedman, K L Pierce, J D Obradovich

Science (New York, N.Y.)

|May 18, 1973

まとめ

オブシディアンの水分化皮の分析は,17万6000年前の火山の位置と,氷河期の出来事と相関する異なる年齢層を明らかにします. この方法は,イエローストーン国立公園の地質学的な形成を年代付けします.

科学分野:

地質化学地質化学
ジオクロノロジー (Geochronology) について
氷河地質学氷河地質学

背景:

イエローストーン国立公園にあるオブシディアン・クリフは,貴重な地質学的記録を提供している.
水分化皮分析は,火山ガラスと地質学的出来事を年代測定するための方法である.

研究の目的:

オブシディアン崖のオブシディアンの水分補給皮の厚さを分析するために.
これらの測定を,火山の転移と氷河化を含む,既知の地質学的な出来事と相関させるため.

主な方法:

オブシディアンの薄い部分の水分化皮の厚さの測定.
カリウムアルゴン年代測定と氷河モレーンによる確立された年代と皮の厚さの比較.

主要な成果:

平均厚さは16.3ミクロメートル,14.5ミクロメートル,7.9ミクロメートルで,水分補給皮の3つの異なるグループが特定されました.
最古の皮層群 (16.3ミクロメートル) は,17万6000年前のオブシディアン流の位置に対応しています.
若い皮層群 (14.5ミクロメートルと7.9ミクロメートル) は,それぞれブル湖とピネデール氷河モレーンのオブシディアン小石と相関しています.

結論:

水分補給皮の厚さは,イエローストーンの地質学的な出来事の年代測定のための信頼できるプロキシを提供します.
裂け目や,水分補給皮が若い表面は,ブル湖とピネデール氷河期における氷河の負荷による形成を示唆しています.

さらに関連する動画

06:48

Fluid-cell Raman Spectroscopy for operando Studies of Reaction and Transport Phenomena during Silicate Glass Corrosion

Published on: May 9, 2025

06:06

Sediment Core Extrusion Method at Millimeter Resolution Using a Calibrated, Threaded-rod

Published on: August 17, 2016

関連する概念動画

01:24

Hydration of Cement

Hydration of cement is a chemical reaction between cement particles and water. This process occurs primarily through two mechanisms: through-solution and topochemical. In the through-solution process, anhydrous compounds dissolve into their constituents, hydrates form in the solution, and then precipitate from the supersaturated solution. The topochemical process involves solid-state reactions at the cement particle surface. The through-solution process dominates the topochemical process at the...

01:19

Specific Gravity of Aggregate

Aggregates typically contain pores, which can be either permeable or impermeable. Considering the pores in the aggregates, the specific gravity of aggregates is defined in three different forms, namely, bulk or gross specific gravity, apparent specific gravity, and absolute specific gravity.
Bulk or gross specific gravity is calculated by taking the ratio of the mass of aggregates in the saturated surface-dry state to the total volume that includes both the solids and the voids within the...

01:20

Porosity and Absorption of Aggregate

Aggregates contain pores of varying sizes; while some are completely enclosed within the particles, others open onto the surface, allowing water to penetrate. The porosity of aggregates is a major factor contributing to the overall porosity of concrete, given that aggregates constitute about three-quarters of concrete's volume.
When all pores in an aggregate are filled with water, the aggregate is considered saturated and surface-dry. If left in dry air, water will evaporate until the aggregate...

01:29

Strength and Heat of Hydration

The hydration of cement is an exothermic reaction in which heat is generated as cement hydrates. This heat of hydration is critical to cement's strength development. The rate at which this heat is generated affects the temperature rise, with a majority of the heat being released early in the hydration process, half within the first three days, and about 75% within the first week.
The heat of hydration for each cement compound is significant; for instance, tricalcium aluminate (C3A) and...

01:10

Moisture Content and Bulking of Aggregate

The moisture content of aggregates is a crucial factor in construction, particularly in concrete mixing, as it influences the total water required in the mix. Moisture content represents the water coated on the exterior surface of the aggregate existing in a saturated and surface-dry condition. The total water content of a moist aggregate is the sum of its moisture content and water absorption.
When aggregates are exposed to rain or sit in stockpiles, they absorb moisture, which must be...

01:50

Global Climate Change

Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global temperatures is well outside of the Earth’s cyclic norms, and evidence for human-caused global climate change is compelling. Paleoclimatology, the study of ancient climate conditions, provides ample evidence for human-caused global climate change by comparing recent conditions with those in the past.

関連する実験動画