静水複合体のレニウム-オスミウムおよびサマリウム-ネオジミウム同位体体系論
まとめ
マグマの混合は,スティルウォーター・コンプレックスにおけるプラチナ系元素 (PGE) 堆積物の形成に重要な役割を果たした. 同位体データは,異なるマグマ源を明らかにし,アノソシートマグマは,鉱石の地平線にオスミウムのような不可欠な元素を寄与しています.
科学分野:
- 地質化学 地質化学
- 経済地質学 経済地質学
- イソトープ地球化学 イソトープ地球化学
背景:
- スティルウォーター・コンプレックス (モンタナ州) は,約2.7億年前に形成されました.
- この複合体の石化過程を理解することは,プラチナ基元素 (PGE) 堆積物の探査に不可欠です.
研究 の 目的:
- 戦略的なPGE鉱石鉱床の形成におけるマグマ混合の役割を調査する.
- 静水複合体の侵入に関与したマグマの同位体シグネチャーを分析する.
主な方法:
- ネオジミウム (Nd) とオズミウム (Os) の同位体データの取得と分析.
- ウルトラマフィック (U型) マグマとアノソシティック (A型) マグマの地化学的特徴の特徴化.
主要な成果:
- 同位体データは,静水複合体は,U型とA型の少なくとも2つの異なるマグマから生じたことを示しています.
- U型マグマはリサイクルされた地殻を持つ石層マントルの源を示し,A型マグマは地殻汚染または地殻下部の融解を示している.
- オスミウムおよび鉱石の地平線 (例えばJ-Mリーフ) に存在する他のPGEsは,A型マグマから発生した可能性がある.
- NdとOsの同位体の異質性は,U型マグマ室にA型マグマの複数の注入を示しています.
結論:
- マグマの混合は,スティルウォーター複合体とその関連するPGE堆積物の形成において重要なプロセスでした.
- U型とA型マグマの異なった同位体組成は,それらの源と進化の経路についての洞察を提供します.
- A型マグマは,J-Mリーフ鉱石埋蔵地内のオスミウムを含むPGEsの主要な源でした.
関連する概念動画
Electron Configuration of Multielectron Atoms
The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go into the lowest-energy subshell available, the 3s orbital, giving a 1s22s22p63s1 configuration. The electrons occupying the outermost shell orbital(s) (highest value of n) are called valence electrons, and those occupying the inner shell orbitals are called core electrons. Since the core electron shells correspond to noble gas electron configurations, we can abbreviate electron...
Nuclear Transmutation
Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with another particle. The first manmade nucleus was produced in Ernest Rutherford’s laboratory in 1919 by a transmutation reaction, the bombardment of one type of nuclei with other nuclei or with neutrons. Rutherford bombarded nitrogen-14 atoms with high-speed α particles from a natural radioactive isotope of radium and observed protons being...
¹H NMR: Pople Notation
The Pople nomenclature system classifies spin systems based on the difference between their chemical shifts. Coupled spins are denoted by capital letters with subscripts indicating the number of equivalent nuclei. When the coupled nuclei have well-separated chemical shifts, they are assigned letters that are far apart in the alphabet, such as A and X. When the difference in chemical shifts is small, coupled nuclei are named using adjacent letters of the alphabet (AB, MN, or XY).
A proton...
A proton...
Chemical Shift: Internal References and Solvent Effects
In an NMR sample, precise measurement of the absolute absorption frequencies of nuclei is difficult. A standard internal reference compound is added, and the frequency difference between the reference signal and sample signals is measured.
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
Elements: 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)...
Nuclear Stability
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together in the...
To hold positively charged protons together in the...


