The

geop

hysi

cal s

igna

ture

of

impa

ct c

rate

rsS

teph

anie

Wer

ner

Obs

erva

tion,

geo

phys

ical

tech

niqu

es a

nd im

plic

atio

ns•

Gra

vity

Ano

mal

ies

•M

agne

tic A

nom

alie

s•

Sei

smic

pro

filin

g •

Ele

ctric

al /E

lect

rom

agne

tic•

Mag

neto

tellu

ric•

Gro

und

Pen

etra

ting

Rad

ar•

Rad

iom

etric

•…

Cra

ter F

orm

atio

n P

roce

ss

Sha

pe:

circ

ular

feat

ures

Mol

tke

Tych

o(2

.7 m

i)(5

3 m

i)

Inve

rted

Stra

tigra

phy:

Met

eor C

rate

r fir

st re

cogn

ized

by

Bar

ringe

r(o

nly

for w

ell p

rese

rved

cra

ters

)

Mat

eria

l dis

plac

emen

t: S

olid

mat

eria

l bro

ken

up a

nd e

ject

edou

tsid

e th

e cr

ater

: bre

ccia

, tek

tites

Slide from B. Pierazzo

Obs

erva

tions

: Phy

sica

lO

bser

vatio

ns: P

hysi

cal

Sha

tter c

ones

: co

nica

l fra

ctur

es w

ith ty

pica

l m

arki

ngs

prod

uced

by

shoc

k w

aves

Sho

cked

Mat

eria

l:sh

ocke

d qu

artz

high

pre

ssur

e m

iner

als

Mel

t Roc

ks:

may

resu

lt fro

m s

hock

an

d fri

ctio

n

Slide from B. Pierazzo

Obs

erva

tions

: Sho

ck E

vide

nce

Obs

erva

tions

: Sho

ck E

vide

nce

Obs

erva

tions

: Geo

phys

ical

dat

aO

bser

vatio

ns: G

eoph

ysic

al d

ata

Gra

vity

ano

mal

y:ba

sed

on d

ensi

ty v

aria

tions

of m

ater

ials

Mag

netic

:ba

sed

on g

ener

alva

riatio

n of

m

agne

tic p

rope

rties

of m

ater

ials

Sei

smic

:so

und

wav

es re

flect

ion

and

refra

ctio

nfro

m s

ubsu

rface

laye

rs w

ith d

iffer

ent

char

acte

ristic

s

Slide from B. Pierazzo

Gra

vity

Ano

mal

ies

Gra

vity

•cr

ater

s ar

e re

lativ

ely

shal

low

feat

ures

, but

dep

ress

ions

•as

soci

ated

to b

recc

iatio

n an

d fra

ctur

ing,

ext

endi

ng to

sig

nific

ant

dept

h be

low

the

crat

er fl

oor

•fra

ctur

ed ro

ck is

less

den

se th

an u

nalte

red

rock

mat

eria

l•

depe

nden

t siz

ean

d m

orph

olog

y, d

ensi

tyco

ntra

st a

nd b

uria

lde

pth

–ci

rcul

ar n

egat

ive

grav

ity a

nom

aly

Gra

vity

ano

mal

y: S

impl

e cr

ater

•N

egat

ive;

unl

ess

fille

d or

er

oded

Gra

vity

ano

mal

y: C

ompl

ex C

rate

r•

frac

turin

gan

d br

ecci

atio

n of

ta

rget

rock

and

min

eral

s•

form

atio

n of

hig

h-pr

essu

re

poly

mor

phs

•m

iner

alog

ic d

iapl

ectic

cha

nge

•up

lift o

f the

rim

wal

l•

form

atio

n of

allo

chto

nous

br

ecci

a an

d m

elt s

heet

s

Com

plex

Cra

ter

Den

sity

Con

trast

142±

640

(25)

150

Sed

imen

tary

Mjø

lnir,

Nor

way

6100

2.35

3212.5

3.8

22km

~550

212

± 1

550

± 10

0

290±

20

~400

450±

30

142.

5 ±

0.5

Ma

kg/m

3

150

Sed

imen

tary

Gos

ses

Blu

ff, A

ustra

lia

170

-340

Cry

stal

line

Bre

nt, C

anad

a

70 –

140

Cry

stal

line

Nic

hols

on L

ake,

Can

ada

170

Cry

stal

line

Cle

arw

ater

Wes

t, C

anad

a

240

Cry

stal

line

Hol

lefo

rd, C

anad

a

130

Cry

stal

line

Man

icou

agan

, Can

ada

160

Cry

stal

line

Söd

erfjä

rden

, Fin

land

177.

5A

vera

ge (C

ryst

allin

e)P

ilkin

gton

& G

rieve

199

2

Gra

vity

Sig

natu

res

Pilk

ingt

on &

Grie

ve 1

992

Sta

tistic

s on

gra

vity

ano

mal

ies

Pilk

ingt

on &

Grie

ve 1

992

Mod

elle

d …

Pilk

ingt

on &

Grie

ve 1

992

Mas

con

Wie

czor

ek 2

007

Typi

cal

Den

sitie

s

Pot

entia

l fie

lds

Gra

vity

Fie

ldM

agne

tic F

ield

Gra

vity

–M

agne

tic F

ield

mon

opol

ardi

pola

r

attra

ctiv

e (+

or -

)at

tract

ive

and

repu

lsiv

e (+

AN

D -)

1/R

2de

pend

ency

1/R

3de

pend

ency

dens

ity v

aria

tions

varia

tion

of m

agne

tic s

usce

ptib

ility

re

flect

s a

bulk

rock

pro

perty

re

flect

s pr

esen

ce o

f tra

ce e

lem

ents

Sou

rce

dept

h is

ver

y no

n-un

ique

so

urce

dep

th w

ithin

10-

20%

acc

urac

y

stab

letim

e de

pend

ent

Mag

netic

Ano

mal

ies

Mag

netic

ano

mal

ies

•m

ore

com

plic

ated

than

gra

vity

•no

spe

cific

sig

natu

re, b

ut

–an

omal

ous

low

or r

ando

m s

igna

ture

inte

rrup

t the

regi

onal

m

agne

tic p

atte

rn (f

ragm

enta

tion

and

mix

ing

of ta

rget

rock

)–

stro

ng lo

cal m

agne

tic a

nom

aly

(mel

t or u

plift

)

–ci

rcul

ar

–if

asso

ciat

ed to

mel

t, it

coul

d be

use

d fo

r pal

aeom

agne

tic d

atin

g

Sei

smic

Ref

lect

ion

or R

efra

ctio

n

Soun

d w

aves

(pul

ses)

are

sen

t dow

nwar

d. T

hey

are

refle

cted

or

refr

acte

d by

laye

rs w

ith d

iffer

ent p

rope

rtie

s in

the

crus

t. D

iffer

ent m

ater

ials

hav

e ve

ry d

iffer

ent s

ound

spe

eds

Sei

smic

stu

dies

•re

fract

ion

and

refle

ctio

n •

reve

alsu

bsur

face

def

orm

atio

n, d

istin

ctiv

e fo

r im

pact

stru

ctur

es–

mod

estd

ownw

ard

and

inw

ard

disp

lace

men

t of r

ocks

alo

ng th

e ed

ges

–st

ruct

ural

disr

uptio

n w

ith n

o co

here

nt s

eism

ic re

flect

ors,

(rou

ghly

co

rres

pond

ing

to th

e tra

nsie

nt c

avity

)–

pres

ence

of re

flect

ors

in th

e ce

ntra

l zon

e at

gre

ater

dep

th, i

s ev

iden

ceth

at th

e st

ruct

ure

is s

hallo

w a

nd n

ot c

onne

cted

with

root

s th

e lo

wer

cr

ust o

r man

tle

–es

sent

ialw

hen

burie

d un

der y

oung

er s

edim

ents

or w

ater

Ele

ctric

al M

etho

ds•

resi

stiv

ityva

riatio

ns d

ue im

pact

rela

ted

targ

et m

odifi

catio

n

–im

pact

indu

ced

incr

ease

d po

rosi

ty a

nd fl

uid

cont

ent (

low

)–

uplif

ted

mat

eria

l (hi

gh)

–ex

tend

sfa

rther

than

the

rim

Glo

bal C

rate

r Dis

tribu

tion

htt

p:/

/ww

w.u

nb.c

a/pas

sc/I

mpac

tDat

abas

e/

Chi

cxul

ub21

°20'

N89

°30'

W17

0km

64.

98 ±

0.0

5 M

a

Chi

cxul

ub

WD

MA

M 2

007

EG

M 2

008

Chi

cxul

ubfil

tere

d m

agne

tic a

nom

alie

s

Pilk

ingt

on &

Hild

ebra

nd 2

000

Chi

cxul

ub

Hild

ebra

nd e

t al.

1995

Bou

guer

gra

vity

horiz

onta

lgra

dien

ts:

high

light

s la

tera

l den

sity

con

trast

san

d su

ppre

sses

regi

onal

ano

mal

ies

Cen

ote

dist

ribut

ion

Chi

cxul

ub

Sha

rpto

net

al.

1996

Hild

ebra

nd e

t al.

1998

Ver

mee

sch

& M

orga

n 20

08

Col

lins

et a

l. 20

08

Glo

bal C

rate

r Dis

tribu

tion

htt

p:/

/ww

w.u

nb.c

a/pas

sc/I

mpac

tDat

abas

e/

Vre

defo

rt

27°0

'S27

°30'

E14

0km

197

0 ±

100

Ma

Geo

logi

cal /

Stru

ctur

al

Inte

rpre

tatio

n

Glo

bal C

rate

r Dis

tribu

tion

htt

p:/

/ww

w.u

nb.c

a/pas

sc/I

mpac

tDat

abas

e/

Rot

er K

amm

27°4

6'S

16°1

8'E

2.5

km 5

± 0

.3 M

a

Rot

er K

amm

Bra

ndt e

t al.

1998

Glo

bal C

rate

r Dis

tribu

tion

htt

p:/

/ww

w.u

nb.c

a/pas

sc/I

mpac

tDat

abas

e/

Mjø

lnir

Google

Ear

th &

Ear

th I

mpac

t D

atab

ase

Mor

phol

ogy

•40

km

in d

iam

eter

•8-

km w

ide

cent

ral u

plift

, 4-

km w

ide

annu

al tr

ough

an

d a

12-k

m w

ide

oute

r zon

eG

udla

ugss

on, 1

993

•ap

pare

nt d

epth

30-

70 m

Tsik

alas

et a

l. 19

98

•V

olgi

an-R

yaza

nian

;142±6

Ma

Dyp

vik

et a

l. 19

96; S

mel

ror e

t al.

2001

Sei

smic

sB

jarm

elan

d P

latfo

rm:

•ho

rizon

tally

laye

red

sedi

men

tary

seq

uenc

es o

f Dev

onia

n to

Ju

rass

ic•

pron

ounc

ed h

oriz

onta

l ref

lect

or m

arki

ng th

e to

p of

the

Per

mia

n su

cces

sion

(Bar

ents

-Sea

wid

e)

•To

pPer

mia

nre

flect

or re

mai

ns u

ndis

turb

ed b

y th

e im

pact

Gudla

ugss

on,

1993

Tsi

kala

s et

al. 1

998

Aer

omag

netic

Sur

vey

(BA

S06

)

Sponso

red

by

Chev

ron,

EniN

org

e, N

orw

egia

n P

etro

leum

Dir

ecto

rate

, RW

E-D

ea N

org

ean

d S

tato

ilHyd

ro.

L.G

ernig

on

and J

.O.

Mogaar

d

colle

cted

and p

roce

ssed

the

surv

ey d

ata.

Cor

e 73

29/0

3-U

-01

•cl

ose

to s

truct

ure

cent

re,

dept

h 17

1m

•to

tal s

usce

ptib

ilitie

s: B

artin

gton

M

S2c

sen

sor i

n co

re-s

cann

ing

set-u

p•

volu

me-

spec

ific

susc

eptib

ilitie

s

•ra

nge:

0-2

00 S

I10-5

;ty

pica

l val

ues

for m

arin

e se

dim

enta

ry ro

cks

•pe

ak v

alue

s fo

und

for s

ider

ite-

cem

ente

d be

ds o

r nod

ules

•ot

her s

ourc

es a

re d

etrit

al

mag

netic

min

eral

s

Mørk, 1999

Gra

vity

NG

U d

atab

ase

Grav.tif

Cor

e 73

29/0

3-U

-01

•cl

ose

to s

truct

ure

cent

re,

dept

h 17

1m

•dr

y bu

lk d

ensi

ties

(mos

t sa

mpl

es d

isso

lve

in w

ater

) •

rang

e 15

00 –

2900

kg/

m3

•w

ere

used

to c

onst

rain

the

uppe

rmos

t lay

ers

of t

he

grav

ity m

odel

Mørk, 1999

Reg

iona

l Tre

nd

NW

SE

A

B

AB

Mod

ellin

gR

esul

tsW

ater

:10

30 k

g/m

3

Unc

onso

lidat

edS

ed.1

: 15

00 k

g/m

3

Unc

onso

lidat

edS

ed.2

: 17

00 k

g/m

3

Con

solid

ated

Laye

red

Sed

.:21

50 k

g/m

3

Bre

ccia

: 23

50 k

g/m

3

Sha

ttere

d Zo

ne:

2450

kg/

m3

Ans

ian

to J

uras

sic

Dep

osits

:25

00 k

g/m

3

Per

mia

n D

epos

its:

2550

kg/

m3

------

------

------

------

------

-C

rust

: 2670

kg/

m3

Glo

bal C

rate

r Dis

tribu

tion

htt

p:/

/ww

w.u

nb.c

a/pas

sc/I

mpac

tDat

abas

e/

Gar

dnos

60°3

9’N

9°0'

E5

km50

0±

10.M

a

Gar

dnos

Gra

vity

and

Mag

netic

Ano

mal

y M

aps

Sum

mar

y•

mai

n at

tribu

te: c

ircul

arity

•us

eful

to d

escr

ibe

the

stru

ctur

al fe

atur

es•

thou

gh n

o pr

oof f

or im

pact

orig

in, g

ood

for c

rate

r det

ectio

n•

Gra

vity

:gen

eral

ly n

egat

ive

anom

aly

•M

agne

tics:

com

plex

and

dep

ende

nt o

n th

e pr

esen

ce o

f m

agne

tic m

iner

al a

ssem

blag

es•

Sei

smic

s: s

truct

ural

info

rmat

ion

•O

ther

Met

hods

: gen

eral

map

ping

•M

odel

ling

is n

eede

d fo

r mor

e in

form

atio

n su

bsur

face

stru

ctur

es•

Cal

ibra

tion

utili

sing

pro

perti

es m

easu

red

in d

rill c

ores