Topic 1. Geologic Time Scale

地质学专业英语课件

Topic 1. Geologic Time ScaleCompiled by OU Qiang, Oct. 2008

Early Life Evolution Lab, China University of Geosciences (Beijing)

地质学专业英语课件

地质学专业英语课件

Division of Geologic Time and RocksGeochronologic Units 地质年代单位) (地质年代单位) Chronostratigraphic Units 年代地层单位) (年代地层单位)

Eon(宙) Era (代) Period (纪) Epoch (世) Age(期)

Eonothem (宇) Erathem (界) System (系) Series (统) Stage (阶)

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Lithostratigraphic Units(岩石地层单位) 岩石地层单位) 超群) Supergroup (超群)

Group (群) Formation (组) Member (段) Bed (层)

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FORMATION The basic lithostratigraphic element is the formation, which is a mappabl rock unit with distinctive upper and lower boundaries.

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Early Cretaceous in Southern Tibet. From older to younger: Gyabula Formation, Chuangde Formation, and Zongzhuo Formation.西藏南部早白垩世地层：自下而上分为加不拉组、床得组、 西藏南部早白垩世地层：自下而上分为加不拉组、床得组、宗卓组

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!Stratotype (Type Section): The designated exposure of a named layered stratigraphic unit or of a stratigraphic boundary that serves as the standard of reference. A stratotype is the specific stratal sequence used for the definition and/or characterization of the stratigraphic unit or boundary being defined. 层型: 层型: 已命名的某地层单位或某地层界线的地质剖面，该剖 面被指定为此地层单位或地层界线的参考标准(即模式剖面)。 1.Unit-stratotype: The type section of a stratigraphic unit that serves as the standard of reference for the definition and characterization of the unit. 单位层型 单位层型:作为定义和识别某个地层 单元的参考标准的模式剖面。 2.Boundary-Stratotype: The specified sequence of strata that contains the specific point that defines a boundary between two stratigraphic units. 界线层型 界线层型:某个指定的地层序列，该地层序 列中含有定义某个地层界线的一个特殊的点。 !GSSP: Global Stratotype (Standard) Section and Point.

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The Meishan Section qualified as GSSP of the Permian-Triassic Boundary浙江长兴煤山剖面被确认为全球二叠系- 浙江长兴煤山剖面被确认为全球二叠系-三叠系界线层型剖面

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1. The development of the geologic time scale in the nineteenth century was based primarily on the fossil record. After many years of collecting fossils from numerous locations, geologists discovered that fossil species succeeded one another in a definite order, and that any period in the geologic history could be recognized by the fossils left behind.

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The fossil record

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2. The construction of the geologic time scale resulted from the work of many geologists who pieced together information from numerous rock exposures and reconstructed a chronology based on changes in the Earth’s biota through time.

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3. The pision of the geo

logic time scale into eons, eras, periods, epochs was primarily based on changes in the fossil record. Therefore, it was originally a relative time scale. Subsequently, with the development of various radiometric dating techniques, geologists have been able to assign absolute dates in years to the subpisions of the time scale and thus can determine how many years ago the various eras, periods, and epochs began.

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Quantitative Measurement of Geologic Time(Absolute Dating): Radiometric Method

Radioactive Parent Isotope Uranium-238 Uranium-235 Thorium-232 Rubidium-87 Potassium-40 Carbon-14

Stable Daughter Isotope Lead-206 Lead-207 Lead-208 Strontium-87 Argon-40 Nitrogen-14

Half-Life in Million Years 4500 704 14000 48800 1250 5730 x 10-6

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Zircon [ZrSiO4](锆石) (锆石)

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Quantitative Measurement of Geologic Time(Absolute Dating): Paleomagnetic Method

地质学专业英语课件

4. The geologic time scale subpides the history of the Earth into a few of hierarchies and many different units. 5. Eons represent the greatest spans of time. There are four eons in the geologic time scale. They are: Hadean, Archean, Proterozoic, and Phanerozoic.