粒状地層の起源と,最も下の大陸の地殻の形成
Science (New York, N.Y.)
|April 21, 1989
まとめ
粒状地殻は,以前考えられていたように,地殻の最も下位の部分ではなく,地殻の中間層を表しています. この発見は,グラヌライトとクセノライトからの圧力データに基づいて,地球の地殻構造に関する私たちの理解を修正しています.
科学分野:
- 地質学 地質学 地質学
- ペトロロジー・ペトロロジーとは
- テクトニクス (地質学) とは
背景:
- 粒状地層は,地球の地殻の進化を理解するための鍵です.
- 以前の仮定では,粒状地殻は地殻の最下層から生じたと考えられていた.
- 粒状のゼノライトは,地殻のより深いプロセスへの洞察を提供します.
研究 の 目的:
- 露出した粒状地層と粒状クセノリトによって表される地殻レベルを区別するために.
- 粒子の形成に関連した地殻の圧力と深さの理解を洗練する.
- 地殻の加厚と粒子の形成の背後にあるメカニズムを調査する.
主な方法:
- グラヌライト・テランとクセノリフの組成の比較分析.
- バランス圧力を測定するために,校正されたバロメーターを適用する.
- 地殻構造の文脈における圧力データの地質学的解釈.
主要な成果:
- 露出した粒状地層は,より低い均衡圧 (0.6〜0.8 GPa,深さ20〜30 km) を記録しています.
- 粒状のゼノライトは,著しく高い圧力 (≥1.01.5 GPa,深さ3550 km) を示しています.
- 粒状地層は,地殻の最下部ではなく,中から下部までの地殻レベルを表しています.
結論:
- 粒状地層は,発掘された最下層の地殻を表しません.
- 地殻-マントルの境界にあるマフィカルマグマの結晶化による地殻の厚み付けは,妥当なメカニズムである.
- このプロセスは,地域的な粒状地層と,深い地殻のマフィカルクセノリトの両方を説明します.
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