コンドルルとカルシウム・アルミニウムに富んだインクルージョンの鉛同位体年齢
Yuri Amelin1, Alexander N Krot, Ian D Hutcheon
1Department of Earth Sciences, Royal Ontario Museum, Toronto, ON M5S 2C6, Canada. yamelin@NRCan.gc.ca
Science (New York, N.Y.)
|September 7, 2002
まとめ
隕石に含まれるカルシウムとアルミニウムが豊富なインクルージョン (CAI) とコンドルールの形成は,何百万年にもわたって起こりました. この研究は,これらの初期の太陽系イベントの正確な年齢制限を提供します.
科学分野:
- 宇宙化学 (コスモケミストリー)
- 惑星科学は惑星科学である.
- ジオクロノロジー (Geochronology) について
背景:
- カルシウムとアルミニウムが豊富なインクルージョン (CAI) とコンドルールは,隕石の原始的な成分です.
- それらの形成のタイムラインを理解することは,初期の太陽系プロセスを解明するために非常に重要です.
研究 の 目的:
- CVコンドライトにおけるCAIの形成と,CRコンドライトにおけるコンドルールの形成の間の年齢間隔を正確に決定する.
- 初期の太陽系におけるCAIおよびコンドルル形成イベントの期間を制限するために.
主な方法:
- Acfer 059隕石のコンドルールの鉛-鉛同位年代測定.
- エフレモフカ隕石のCAIの鉛同位体年代測定.
- 最初の26Al/27Al比率の分析.
主要な成果:
- リード・リード・イソクロン年齢は4564.7 ±0.6万年前です.
- CV CAIの鉛同位体の年齢は4567.2 ± 0.6 Maである.
- これは,CV CAIとCRコンドルル形成の間の2.5 ± 1.2百万年 (My) の間隔を示し,イベントは少なくとも1.3 My.続きます.
結論:
- CAIとコンドルル形成は,太陽系初期の重要な期間をカバーしました.
- 決定された時間間隔は,26Al-26Mgの体系化に基づいた時系列と一致しています.
- これは,太陽系物質の年代測定における26Al-26Mgイソトープ比の年代的重要性を裏付けるものである.
関連する概念動画
01:12Isotopes
Elements have a set number of protons that determines their atomic number (Z). For example, all atoms with eight protons are oxygen; however, the number of neutrons can vary for atoms of the same element. The sum of the number of protons and the number of neutrons is the mass number (A). Atoms with the same atomic number but different mass numbers are called isotopes. Elements can have multiple isotopes, for example, carbon-12, carbon-13, and carbon-14.An element's atomic mass, or weight, is a...
02:31Elements: Chemical Symbols and Isotopes
A chemical symbol is an abbreviation used to indicate an element or an atom of an element. For example, the symbol for mercury is Hg. The same symbol is used to indicate one atom of mercury (microscopic domain) or to label a container of many atoms of the element mercury (macroscopic domain).
Some symbols are derived from the common English name of the element; others are abbreviations of the name in another language — Latin, Greek or German. For example, the symbol for aluminum (common name)...
Some symbols are derived from the common English name of the element; others are abbreviations of the name in another language — Latin, Greek or German. For example, the symbol for aluminum (common name)...
04:00Periodic Classification of the Elements
The periodic table arranges atoms based on increasing atomic number so that elements with the same chemical properties recur periodically. When their electron configurations are added to the table, a periodic recurrence of similar electron configurations in the outer shells of these elements is observed. Because they are in the outer shells of an atom, valence electrons play the most important role in chemical reactions. The outer electrons have the highest energy of the electrons in an atom...
03:46Qualitative Analysis
For solutions containing mixtures of different cations, the identity of each cation can be determined by qualitative analysis. This technique involves a series of selective precipitations with different chemical reagents, each reaction producing a characteristic precipitate for a specific group of cations. Metal ions within a group are further separated by varying the pH, heating the mixture to redissolve a precipitate, or adding other reagents to form complex ions.
For instance, group IV...
For instance, group IV...
02:48Radioactive Decay and Radiometric Dating
Radioactivity is a spontaneous disintegration of an unstable nuclide and is a random process, as all the nuclei in the sample do not decay simultaneously. The number of disintegrations per unit time is called the activity (A), which is directly proportional to the number of nuclei in the sample. The decay constant (λ) is an average probability of decay per nucleus in unit time.
01:29Imperfections in Crystal Structure: Non-Stoichiometric Defects
Non-stoichiometric defects refer to a type of defect in the crystal structure of a compound where the ratio of its constituent elements deviates from the ideal stoichiometric ratio. There are two main types of non-stoichiometric defects: metal excess defects and metal deficiency defects.Metal excess defects occur when there is a slight surplus of metal ions than what is required by the stoichiometric ratio of the compound. For example, heating a sodium chloride crystal in sodium vapor results...