大三啦-大地構(gòu)造

大地構(gòu)造學(xué)（Tectonics）4.

Plate

tectonics:

A

UnifyingTheoryA

unifying

theory

is

one

that

helpsexplain

abroad

range

of

diverse

observationsinterpret

many

aspects

of

a

science

on

a

grand

scaleand

relate

many

seemingly

unrelated

phenomenaPlate

tectonics

is

a

unifying

theory

for

geology.(1)

A

Unifying

TheoryPlate

tectonics

helps

to

explainearthquakesvolcanic

eruptionsformation

ofmountainslocation

ofcontinentslocation

of

oceanbasinsTectonic

interactionsaffectatmospheric

and

oceaniccirculation

and

climategeographic

distribution,evolution

and

extinctionof

organismsdistribution

andformation

of

resourcesPlate

tectonics

is

a

unifying

theory

for

geology1912年魏格納

大陸漂移說，后經(jīng)E.Argand(1924)、A.Holmes(1928)、OuToit(1937)等進(jìn)一步發(fā)揮，然而最終未能成為大地構(gòu)造學(xué)派的主流思想。The

continental

drift

theory

wasgenerally

accepted

ingeosciencesonly

during

the

second

half

of

the20th

century,

after

the

hypothesesof

Alfred

Wegener

had

beensupported

through

the

discovery

ofa

mechanism

for

continental

drift,and

an

adequate

energy

source,

inthe

convection

currents

of

theplastic,

very

weak

upper

mantle,

orasthenosphere.二十世紀(jì)50年代，英國物理學(xué)家

M.P.S.Blackeet、S.K.Runcorn通過對(duì)大陸古地磁的測(cè)量和研究，以精確的數(shù)據(jù)說明了大陸間的相互位移，促使大陸漂移學(xué)說的復(fù)興。板塊構(gòu)造學(xué)說的建立是一個(gè)復(fù)雜、坎坷的歷程（1910-1970年)In

1947,Blackett

introduced

a

theory

to

account

for

the

Earth's

magnetic

field

as

a

function

of

itsrotation,

with

the

hope

that

it

would

unify

both

the

electromagnetic

force

and

the

force

of

gravity.

Hespent

a

number

ofyearsdevelo

high-quality

magnetometers

to

test

his

theory,and

eventuallyfound

it

to

be

without

merit.

His

work

on

the

subject,

however,

led

him

into

the

field

of

geophysics,wherehe

eventually

helped

process

data

relating

to

paleomagnetism

and

helped

to

provide

strongevidence

for

continental

drift.In

1965

he

was

invited

to

deliver

the

MacMillan

Memorial

Lecture

to

the

Institution

of

Engineers

andShipbuilders

in

Scotland.

He

chose

the

subject

'Continental

Drift‘.Stanley

Keith

Runcorn

(19

November

1922

–

5

December

1995)

was

a

British

physicist

whosepaleomagnetic

reconstruction

of

the

relative

motions

of

Europe

and

America

revived

the

theory

ofcontinental

drift

and

wasa

major

contribution

to

plate

tectonics.地質(zhì)學(xué)家H.H.Hess(1960,1962)提出了海底擴(kuò)張說，后來得到R.S.Dietz(1961)、F.J.Vine,D.H.Matthews(1963)、J.T.Wilson(1965)、J.R.

Hentzler(1968)等進(jìn)一步的論證和完善。3. W.J

Morgan、X.Le

Pichon、D.P.

Mekenzie、B.

Isacks等于1968年 地質(zhì)學(xué)會(huì)年會(huì)上闡述了板塊構(gòu)造學(xué)說。K.Condie,

2003Plate

tectonic

theory

is

based

on

the

simple

modelthat:the

lithosphere

isrigidPlate

Tectonics固體地球上層在垂向上可分為性質(zhì)不同的兩個(gè)圈層。即上部的剛性巖石圈，下部的軟流圈。巖石圈在側(cè)向上被一些構(gòu)造活動(dòng)帶分割成若干既不連續(xù)、又互相“鑲嵌”起來的大小不一球面塊體，每個(gè)塊體的厚度相對(duì)于其面積及地球半徑來說是很薄的，呈板狀，故稱為巖石圈板塊(簡(jiǎn)稱板塊)。Plate

TectonicsPlate

tectonic

theory

is

basedon

the

simple

model

that:2.

The

lithospheric

plates

overliehotter

and

weaker

semiplasticasthenosphere,

a

zone

of

partialmelting.堅(jiān)硬的巖石圈板塊馱在塑性的軟流圈之上，橫跨在地球表面上發(fā)生大規(guī)模的水平移動(dòng)。Plate

tectonic

theory

is

based

on

the

simplemodelthat3.

it

consists

of

oceanic

and

continental

crustwith

upper

mantle,

with

plate

regionscontaining

continental

lithosphere

up

to250

km

thick,

and

plate

regions

containingoceani hosphere

up

to

100

km

thickPlate

TectonicsPlate

tectonic

theory

is

based

on

the

simple

modelthat4.

it

consists

of

variable-sized

pieces

called

platesPlate

TectonicsPlate

TectonicsPlate

tectonic

theory

is

based

on

the

simple

model

thatas

plates

move

over

theasthenospherethey

separate,

mostly

at

oceanic

ridges;or

break

into

new

and

smallerplates;在板塊分離處，軟流圈內(nèi)的地幔物質(zhì)上涌，冷凝構(gòu)造成新的洋殼，使板塊新生；Plate

TectonicsPlate

tectonic

theory

is

based

on

the

simple

model

thatas

plates

moveover

the

asthenospherethey

collide

to

form

orogenic

belts

and

amalgmated

into

new

andlarger

plates;in

areas

such

as

oceanic

trenches

where

they

maybe

subducted

backinto

the

mantle;在板塊匯聚處，一個(gè)板塊俯沖到另一個(gè)板塊之下，使之返回地幔同化，導(dǎo)致板塊的消亡。Plate

tectonic

theory

is

based

on

the

simple

model

thatAs

plates

move

over

the

asthenospherethey

form

strike-slip

fault(transform

fault)

across

the

oceanicridges.Plate

TectonicsAfricaNorth

AmericaSouth

AmericaEuropeAtlanticOceanbasinPlate

TectonicsPlate

tectonic

theory

is

based

on

the

simple

model

thatthree

types

of

plate

boundaries

are

zones

of

most

activeon

the

earth’s

surface:volcanoes,

earthquakes,

deformationlocalizatioin…板塊的相互運(yùn)動(dòng)，激起了和火山活動(dòng)，推動(dòng)了大陸漂移和大洋盆地的張開與關(guān)閉，也導(dǎo)致了地殼上各種地質(zhì)構(gòu)造的產(chǎn)生和各種礦產(chǎn)的形成。Plate

TectonicsPlate

tectonictheory

is

based

on

the

simple

model

thatthree

types

of

plate

boundaries

are

zones

of

most

activeon

the

earth’s

surface:But

the

continental

plates

retain

rocks

with

a

longgeologicalhistory.

較輕的大陸板塊，總是馱在軟流圈之上漂移，難以消亡掉。因此陸殼上保持有3600Ma以上的地質(zhì)歷史記錄。(2)

Types

of

PlatesPlate

or

Lithospheric

plate:

2

types“板塊”這一術(shù)語，系1965年Wilson在論述轉(zhuǎn)換斷層時(shí)首先（巖石圈）并不是。整個(gè)地球的表殼續(xù)完整的圈層，它被首尾相接的活動(dòng)帶（洋中脊、海溝和轉(zhuǎn)換斷層）分割成大小不一的塊體，叫做巖石圈板塊，簡(jiǎn)稱板塊。全球的帶是板塊邊界的相對(duì)運(yùn)動(dòng)造成的，這樣全球各帶相互交接、首尾相連，它們把巖石圈劃分為若干

較弱的板塊。1)

Six-plate

subdivisionX.Le

Pichon，1968）以陸殼巖石圈為主體的板塊稱為陸殼型板塊－－歐亞、

、南美、非洲、以洋殼巖石圈為主體的板塊稱為洋殼型板塊－－太平洋、菲律賓海、

－澳大利亞、南極洲、可可、加勒比、納茲卡Numbers

represent

average

rates

of

relative

movement,

cm/yr2)

Twelve-plate

subdivision

(Mckenzie

et

al.,

1976)PLATE

TECTONICS

—Plate

interiorNot

as

simple

as

it

looks

on

this

map2)

大陸的板塊沿大陸 大型板塊邊界，往往鑲嵌著眾多的小型板塊，如歐亞板塊南緣的阿爾卑斯—喜馬拉雅活動(dòng)帶，就鑲嵌著一系列小板塊。在地中海區(qū)，加勒比海區(qū)同樣也存在著一系列小板塊。其運(yùn)動(dòng)不是由于地幔對(duì)流所驅(qū)動(dòng)，而是從屬于塊的運(yùn)動(dòng)而運(yùn)動(dòng)。Areasofwide

plate

boundary

deformation巖石圈板塊所作大規(guī)模的水平運(yùn)動(dòng)，是一種在球面上的繞軸旋轉(zhuǎn)運(yùn)動(dòng)?？捎脷W拉定律來描繪。板塊沿分離型邊界擴(kuò)張、增生；與此同時(shí)它又沿匯聚型邊界縮減、消亡，相互補(bǔ)償，使地球半徑保持不變。Plate

Tectonics（3）板塊的三聯(lián)點(diǎn)與運(yùn)動(dòng)在板塊分布圖上，?？梢姷饺龡l板塊邊界相交于一點(diǎn)，這個(gè)點(diǎn)與三個(gè)板塊相鄰接，叫做板塊的三聯(lián)接合點(diǎn)(或三結(jié)點(diǎn))。任何一對(duì)板塊間的邊界總是以三聯(lián)接合點(diǎn)作接合點(diǎn)也有可能出現(xiàn)，接合點(diǎn)會(huì)立即轉(zhuǎn)化為兩個(gè)為端點(diǎn)。在理論上，但在一般情況下，

三聯(lián)接合點(diǎn)。與三聯(lián)接合點(diǎn)相接的板塊邊界，可以是分離型、匯聚型或平錯(cuò)型邊界。在理論上，這三類邊界可以組十六種不同的情況，可以出現(xiàn)十六種不同的三聯(lián)接合點(diǎn)類型。如以R代表裂谷，T代表海溝，F(xiàn)代表轉(zhuǎn)換斷層，則RRR型就是裂谷—裂谷—裂谷型的三聯(lián)接合點(diǎn)；RTF型代表裂谷—海溝一斷層型的三聯(lián)接合點(diǎn)，其余類推。在

洋中部，洋中脊三條分支的交點(diǎn)是非洲板塊、板塊和南極洲板塊之間的RRR型三聯(lián)；RRR型分布最廣在

洋中部，

洋中脊三條分支的交點(diǎn)是非洲板塊、 板塊和南極洲板塊之間的RRR型三聯(lián)；非洲東北部的阿法爾三角地區(qū)，是紅海裂谷、亞丁灣裂谷和東非大裂谷相交接的三聯(lián)；太平洋東部加拉帕戈斯群島附近，是太平樣板塊、可可板塊和納茲卡板塊之間的RRR型接合點(diǎn)。非洲東北部的阿法爾三角地區(qū)，是紅海裂谷、亞丁灣裂谷和東非裂谷相交接的三聯(lián)；中脊，向東沿亞速爾-直布羅陀一線，主要板塊、歐亞板塊和非洲板塊之間的RRF型接RRF型三聯(lián)點(diǎn)分布于 洋脊上從亞速爾群島向北和向南為是平移滑動(dòng)邊界，亞速爾乃是合點(diǎn)。TTT型見于

本州島東南部海溝、西南

海溝和小笠原海溝在這里相接，成為歐亞板塊、菲律賓海板塊和太平洋板塊之間的三聯(lián)點(diǎn)。其他接合類型如RTT型、RRT型十分少見。一些三聯(lián)接合點(diǎn)類型，如RRR型是穩(wěn)定的，隨著板塊運(yùn)動(dòng)，有保持自己形狀的趨勢(shì)。另有些三聯(lián)接合點(diǎn)則是不穩(wěn)定的，隨著板塊運(yùn)動(dòng)，它們很快改變自己的外形。海溝、琉球海溝和小笠原海溝在這里相接，成為歐亞板塊、菲律賓海板塊和太平洋板塊之間的三聯(lián)點(diǎn)(TTT型)。魏格納提出，潮汐摩擦力和離極力可作為驅(qū)使大陸漂移的原動(dòng)力。據(jù)杰弗利斯計(jì)算，地球自轉(zhuǎn)與潮汐引起的作用力都太小，難以驅(qū)動(dòng)大陸漂移。大多數(shù)學(xué)者相信，板塊驅(qū)動(dòng)主導(dǎo)機(jī)制應(yīng)是某種形式的地幔與巖石圈的相互作用。Driving

forces

:

Different

models(3)

Plate

Tectonics-mechanisms1)

Mantle

convectionmodel:

Movement

of

the

platesresults

from

some

type

of

heat-transfer

systemwithin

the

athenosphere.關(guān)于地幔對(duì)流的規(guī)模也有不同的主張。在極塊構(gòu)造學(xué)說初創(chuàng)時(shí)期，當(dāng)時(shí)認(rèn)為下地幔的粘度遠(yuǎn)大于上地幔，那里不可能發(fā)生對(duì)流，因而主張對(duì)流局限于上地幔，即淺對(duì)流模式。70年代以來，學(xué)者們認(rèn)識(shí)到上、下地幔的粘度相差不大，又主張全地幔對(duì)流，即深對(duì)流模式。后來發(fā)現(xiàn)大洋脊的玄武巖與大洋島的玄武巖在地球化學(xué)上的明顯差異，于是淺對(duì)流模式又興起，同時(shí)提出上、下地幔的雙層對(duì)流模式。Moores

and

Twiss,

19952)熱柱是由Wilson(1963)在解釋火山島鏈成因時(shí)首先提出來的。Morgan(1971)進(jìn)一步發(fā)展了這一概念。熱柱是從核-幔邊界升騰而起的一股熱流柱體，直徑可達(dá)幾百公里，它可能是由液態(tài)外核傳遞的能量引發(fā)的。也有人認(rèn)為地幔柱是熱地幔上升形成的底辟體。類似沉積巖中的鹽丘。Hot