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1 Primary & Middle School Mathematics1–9 年级在线 2 High School Mathematics10–12 年级在线 3 University Mathematics — Year 1本科一年级在线 4 University Mathematics — Year 2本科二年级在线 5 University Mathematics — Year 3本科三年级在线

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1 Markets I: The Ecosystem and Exchange-Traded Markets市场在线 2 Markets II: Rates, FX and Credit市场在线 3 Markets III: Commodities, Energy and Crypto市场在线 4 Quantitative Methods方法在线 5 Derivatives and Volatility衍生品在线 6 Rates, Credit, XVA and Risk利率、信用与风险在线 7 Research Craft: Predictors, Backtests, Measurement, Portfolios研究在线 8 Strategies I: Equities and Futures策略在线 9 Strategies II: Volatility, Relative Value, Macro and the Bank Desks策略在线 10 Microstructure and Execution交易执行在线 11 Market Making and High-Frequency Trading做市在线 12 Machine Learning for Markets机器学习在线 13 Low-Latency Software技术在线 14 Networks, Hardware and Trading Infrastructure技术在线 15 Research, Data and Risk Platforms技术在线 16 The Desk and the Firm公司运营在线 17 The Industry: Firms, Roles and Careers职业发展在线 18 Interviews I: Maths, Probability and Speed职业发展在线 19 Interviews II: Markets, Trading Games and the Final Round职业发展在线 20 Interviews III: Code职业发展在线

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Earth and Space Sciences · 术语表

什么是 Bracketing age？

Definition 25.14 University Earth and Space Sciences — Year 1 · 第 25 章 — Radiometric Dating Methods

A bracketing age is a limit placed on the age of a sedimentary level by dated rocks related to it by the principles of stratigraphy: a maximum age from a dated layer below it, or from the youngest detrital grain in it; a minimum age from a dated layer above it, or from an intrusion that cuts it. A level between a maximum and a minimum is bracketed.

Ages that bracket a level in a sedimentary sequence (schematic). The ash bed below and the youngest detrital zircon in the sandstone give maximum ages; the lava flow above and the dyke that cuts the whole sequence give minimum ages. The level is younger than t_1 and older than t_2; the dyke adds only that it is older than t_3. — Ages that bracket a level in a sedimentary sequence (schematic). The ash bed below and the youngest detrital zircon in the sandstone give maximum ages; the lava flow above and the dyke that cuts the whole sequence give minimum ages. The level is younger than $t_1$ and older than $t_2$ ; the dyke adds only that it is older than $t_3$ .

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