概括
新的-测年法揭示了印度东部的古代地演变,岩石可以追溯到3.775亿年前. 这与之前的鲁比-测年相反,表明复杂的地质过程和早期地幔分化.
科学领域:
- 地质化学 地质化学
- 同位素地质学的同位素.
- 古代地质学 古代地质学
背景情况:
- 印度东部的辛格布姆花岩宝石中含有较古老的gneisses的遗迹.
- 以前使用鲁比-测年法进行的地质年代学研究显示,这些岩石的年龄为3.2亿年.
- 为了理解古老地的演变,需要精确的地质年代数据.
研究的目的:
- 为了更准确地确定辛格布姆花岩宝石中的花岩和色状岩的年龄.
- 调查印度东部的阿凯纪地的早期演变.
- 评估大约3.8亿年前地球地幔的分化状态.
主要方法:
- 对九个花岩和色素岩格内斯样本进行了- (Sm-Nd) 同位素分析.
- 使用Sm-Nd数据进行同步约会,以确定年龄和初始同位素比率.
- 集成Sm-Nd数据与现有的现场和岩石学数据.
主要成果:
- 根据SM-Nd等离子测年法,格尼斯的年龄为3.775 ± 8.9亿年.
- 最初的 (143) Nd/(144) Nd比率被确定为0.50798 ± 0.00007.
- 这种Sm-Nd年龄与先前报告的3200亿年卢比-年龄形成了显著的对比.
结论:
- Sm-Nd数据表明辛格布姆石的年龄要大得多,这表明了印度东部的阿凯纪地演变的修订时间表.
- 这些发现支持了基于综合地质年代学,现场学和岩石学证据的阿凯纪地的演化方案.
- 同位素证据表明,地球地幔的部分已经在3.8亿年前就已经与合体Sm-Nd比率差异化.
相关概念视频
Conditions on Early Earth
Around 4 billion years ago, oceans began to condense on earth while volcanic eruptions released nitrogen, carbon dioxide, methane, ammonia, and hydrogen into the primordial atmosphere. However, organisms with the characteristics of life were not initially present on earth. Scientists have used experimentation to determine how organisms evolved that could grow, reproduce, and maintain an internal environment.
Conditions on Early Earth
Around 4 billion years ago, oceans began to condense on earth while volcanic eruptions released nitrogen, carbon dioxide, methane, ammonia, and hydrogen into the primordial atmosphere. However, organisms with the characteristics of life were not initially present on earth. Scientists have used experimentation to determine how organisms evolved that could grow, reproduce, and maintain an internal environment.
The Fossil Record
The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...
Isothermal Processes
A thermodynamic process that occurs at constant temperature is called an isothermal process. Heat slowly flows into the system or out of the system to maintain thermal equilibrium. Processes involving phase changes like water evaporation into steam or freezing water into ice at a constant temperature are examples of Isothermal Processes.
An ideal gas can also undergo isothermal expansion or compression.
For example, consider 1 mole of an ideal gas inside an isolated cylinder at initial volume V...
An ideal gas can also undergo isothermal expansion or compression.
For example, consider 1 mole of an ideal gas inside an isolated cylinder at initial volume V...
Diversity of Archaea III
Crenarchaeota, a prominent phylum of Archaea, is remarkable for its ability to thrive in extreme environments characterized by high temperatures and acidity. These microorganisms inhabit sulfuric hot springs, volcanic systems, and submarine hydrothermal vents, where temperatures often exceed 100°C. The unique adaptations of Crenarchaeota not only allow survival under such extreme conditions but also provide insights into the mechanisms of life in primordial Earth-like environments.Morphological...
Diversity of Archaea I
Archaea, a domain of single-celled microorganisms, are classified into five major phyla based on genetic and biochemical characteristics: Euryarchaeota, Crenarchaeota, Thaumarchaeota, Korarchaeota, and Nanoarchaeota. Among these, the phylum Euryarchaeota is notable for its remarkable diversity in morphology, metabolism, and ecological adaptations.Morphological and Metabolic DiversityMembers of Euryarchaeota exhibit a variety of cellular shapes, including rods and cocci. Their metabolic pathways...


