北京大学 地球科学基础 Lecture16 地质年代.pdf

Chapter16

GeologicTime

地质年代

Outline

•IntroductiontoGeologicTime

•RelativeDatingMethods

–FundamentalPrinciplesofRelativeDating

–Unconformities

•CorrelatingRockUnits

•AbsoluteDatingMethods

•DevelopmentoftheGeologicTimeScale

•StratigraphyandStratigraphicTerminology

•GeologicTimeandClimateChange

Introduction

类似于社会年代，对整个地球发展演化的历史、

对地质历史中发生的地质事件的论述、记述、研究也

需要一套相应的地质年代。

相对年代（地质事件发生的先后顺序）

地质年代relativedating

绝对年代（地质事件发生距今多少年）

absolutedating

TheGeologicTimeScale

Aworld-widerelative

timescaleofEarths

rockrecordwas

establishedbythe

workofmany

geologistsapplyingthe

principlesofhistorical

geologyand

correlationtostrataof

allagesthroughout

theworld.

RelativeDatingMethods

•Beforethedevelopmentofradiometricdating,therewas

noreliablemethodforabsolutedating,thereforerelative

datingmethodswereused.

–Relativedatingplaceseventsinsequentialorderbutdoes

nottellushowlongagoaneventtookplace.

FundamentalPrinciplesofRelativeDating

1.Superposition叠覆律

2.Originalhorizontality原始地层水平律

3.Lateralcontinuity侧向连续律

4.Cross-cuttingrelationships切割穿插律

5.Inclusions包裹体律

6.Fossilsuccession生物层序律

Superposition叠覆律

•Superpositionstatesthat,inanundisturbedsuccessionof

sedimentarylayers,theoldestlayerisonthebottomand

theyoungestlayerisonthetop.

OriginalHorizontality原始地层水平律

•Originalhorizontalitystatest