Table 5-1 Some of the More Useful Nuclides for Radioactive Dating Half- Life Daughter tent nuclide* (in years)' Nuclide Materials Dated 5730 Nitrogen 14 Organic materials Uranium 235 704 million(7.04 X lor Lead 207 (and helium Zircon, uraninite pitchblende Potassium -40 125 1 million (1.25 x 10) Argon 40 (and calcium 40) Muscovite, biotite. hornblende, volcanic rock glauconite. K-felds Uranium 2 58 4468 million (4.47X 10) Lead 206(and helium) Zircon, uraninite, pitchblende Rubidium S7 48, 800 million (4.88x 10) Strontium 87 K-micas, K-feldspars, biotite metamorphic rock, glauconite *A nuclide is a convenient term for any particular atom (recognized by its particular combination of neutrons and protons. Half-life data from Steiger. R H. and Jager, E. 1977. Subcommission on geochronology: convention on the use of decay constants in geo-and cosmochronology. Earth and Planetary science Letters 300: 359-362 agh potassium 40)decays to argon 40 and calcium 40). only argon is used in the dating method because most minerals contain considera calcium l0) even hefore decay has begun 同位素年龄测定
同位素年龄测定
磁性地层划分对比/ Magnetostratigrapgy 地层中通常可以保存 沉积物沉积或成岩期 的磁性特征,即“剩 余磁性”。地史中地 磁极曾发生许多次倒 转。根据地磁极的倒 转并配合同位素年龄 测定,可以建立一个 地磁极向年表。由于mm066Mad 地球的磁极是全球性 such as those of the hawaiian island volcanoes retain a re- cord of the Ear th's magnetic field when they cool below the 的,利用地磁极向年 Curie point. Each magnetic reversal can be dated by the potassium-argon dating technique. b Magnetic reversals for 表可以对地层定年和 last 4.5 million years as determined from lava flows on land 进行磁性地层的对比 Dark bands represent normal magnetism and white bands represent reverse magnetism
地层中通常可以保存 沉积物沉积或成岩期 的磁性特征，即“剩 余磁性”。地史中地 磁极曾发生许多次倒 转。根据地磁极的倒 转并配合同位素年龄 测定，可以建立一个 地磁极向年表。由于 地球的磁极是全球性 的，利用地磁极向年 表可以对地层定年和 进行磁性地层的对比 磁性地层划分对比/ Magnetostratigrapgy
Magnetic reversal Magnetic time scale Magnetic imprint Epochs (in millions of years) in layered basalts 更新世磁极 Brunhes Normal Epoch.5 倒转时间表 1.0 Matuyama Reversed.5 figure 8-44 The imprint of normal and reversed Epoch magnetic polarity in a composite section of layered 2.0 2.5 netic reversal time scale is shown in the center col Gau Normal cA v2 3.0 after famous investigators of magnetic effects. The 3.5 magnetic epochs reflect a predominance of one kind Gilbert 4.0 Reversed Epoch 4.5 magnetic events of shorter duration. (Modified from 5.0 A. Cox. Science63:237-245.1969
更新世磁极 倒转时间表 Gilbert Reversed Epoch Matuyama Reversed Epoch
地震地层划分对比 Recording Van ⊙( Regolith Detectors shot Hole Dynamite Seismic Blast Reflection Record from 12 Detectors Seismic stratigraphy Reflected Waves Shale Reflecting Stratum Record of Reflecting Stratum Figure 3-40 The principle of seismic reflection surveying
Seismic stratigraphy 地震地层划分对比
Logging stratigraphy A R Magnetic recording Mechanical winching drum Loggin Instant display Digital transmittal Surface compute 测拜 Down hole 地层 tool 划分 对比
测井 地层 划分 对比 Logging stratigraphy