self-organized breakup of gondwana by jim sears university of montana main conclusions: breakup of...

SELF-ORGANIZED BREAKUP OF GONDWANA

byJIM SEARS

UNIVERSITY OF MONTANA

MAIN CONCLUSIONS:

BREAKUP OF GONDWANA WAS SELF-ORGANIZED TO MINIMIZE

WORK

ARGUES AGAINST DEEP MANTLE PLUMES

HEARD ISLAND HOT SPOT

THE DEEP MANTLE PLUME PARADIGM: AN INTEGRAL PART OF PLATE TECTONICS SINCE

J.T. WILSON (1963) AND W.J. MORGAN (1981)

STATIONARY HOT SPOT VOLCANOES:TAILS OF DEEP MANTLE PLUMES?

LARGE IGNEOUS PROVINCES (LIPS): HEADS OF DEEP MANTLE PLUMES?

HEADS AND TAILS LINKED BY HOT SPOT TRACKS?

PLUMES RANDOMLY GENERATED AT CORE-MANTLE BOUNDARY?

PLUME OUTBREAKS INITIATE CONTINENTAL BREAKUP?

GONDWANA

AUST

ANTARCTICA

NZ

AF

SA

INDIA

1999 UTIG

ACCEPTED MODEL FOR GONDWANA BREAKUPLAWVER ET AL. 1999

CAMP - FERNANDO

1999 UTIG

KAROO-BOUVET

1999 UTIG

GALLODAI-MARION

1999 UTIG

PARANA-TRISTAN

1999 UTIG

RAJMAHAL-KERGUELEN

BANBURY-HEARD

1999 UTIG

HOTSPOT CONSTELLATION

AFRICA

SOUTHAMERICA

INDIA

ARABIA

ANTARCTICA

AU

STR

ALI

A

N Z

HOWEVER, BREAKUP OF GONDWANA WAS NOT

RANDOM - IT WAS HIGHLY SELF-ORGANIZED

FLO

RID

A

ETHIOPIAN

38 Ma

LARGE IGNEOUS PROVINCES

DECCAN65 Ma

RAJMAHAL

110 Ma

PARANA 134 Ma

GALLODAI144 MaKAROO

183 Ma

FERRAR183 Ma

CAMP 205 Ma

LIMPOBO

TRANSKEI

MARANHAO 200 Ma

GONDWANA HOT SPOT FAMILY

HEARD

ST HELENA

MARION

BOUVETFERNANDO

TRISTAN

GOUGH

CROZETKERGUELE

NASCENCION

THESE MAJOR GONDWANA

FRACTURE POLYGONS RIGOROUSLY OBEY EULER’S THEOREM

FOR CONVEX POLYTOPES

BEN

UE

TA

CU

TU

GO

DAV

AR

I

WED

ELL

TRANSKEI

PER

U-P

ARAGUAY

DIS

CONTI

NUIT

Y

NAMELY, TO TILE A SPHERE WITH 12 +

PLATES, 12 MUST HAVE 5-FOLD SYMMETRY AT PRECISELY-DEFINED

VERTICES OF ICOSAHEDRON

GONDWANA

REMAINING (N-12) PLATES HAVE 6-

FOLD SYMMETRY

GONDWANA

Euler’s formula relating faces (F), vertices (V ), and edges (E) of a convex polytope (F + V = E + 2)

ICOSAHEDRAL ARRANGEMENTS

ICOSAHEDRAL VIRUS

HERPES SIMPLEX

FINITE ELEMENT SOLUTION FOR

THOMSON PROBLEM WITH 912

CHARGES ON SPHERE

(Altschuler et al., 1997)

EDGE LENGTHS AND CENTERS

ARE RIGOROUSLY DEFINEDEACH EDGE = 2600 KM AT

EARTH SCALE

GONDWANA

ANTARCTICA

PENTAGONRIFT EDGES ~

2600 KM

2600

KM

2600 KM 2600 KM

GONDWANA

PENTAGONS AND HEXAGONS IN EXACT ARRANGEMENT

PP

H

H

HH

H

P

GONDWANA

PP

H

H

HH

H

P

16 EDGES,>20,000 KM

PATTERN MINIMIZES TOTAL FRACTURE LENGTHAND THEREFORE MINIMIZES WORK

FUNCTION OF STRENGTH OF GONDWANA SHELL

GONDWANA

STRONGER

WEAKER

GONDWANA

PATTERN MINIMIZES TOTAL FRACTURE LENGTHAND THEREFORE MINIMIZES WORK

FUNCTION OF STRENGTH OF GONDWANA SHELL

GONDWANA

STRONGER

WEAKER

GONDWANAX

LARGE IGNEOUS PROVINCES ERUPTED DIACHRONOUSLY ALONG FRACTURE

PATTERN

DEPENDED ON PLATE TECTONICS TO OPENFRACTURES TO INDUCE DECOMPRESSION

MELTING

CONCORDANCE OF FAMILY OF HOT SPOTS WITH FRACTURE TESSELLATION

SHOWS HOT SPOTS ARE NON-RANDOM

HOTSPOTS ON TESSELLATION

YELLOW STRESS TESSELLATION IS DUAL OF FRACTURE TESSELLATION:

THEY CROSS ONE ANOTHER ORTHOGONALLY

HOTSPOTS ON TESSELLATION

HOOP STRESS ALONG NORTHERN GONDWANA MARGIN

NOTE RADIAL FRACTURES AT MARGIN

HOTSPOTS ON TESSELLATION

NOTE PERFECT SYMMETRY OF STRESS TESSELLATION ACROSS

GONDWANA

HOTSPOTS FAVOR CENTERS

EXPANSION OF GONDWANA LEADS TO FRACTURES

FRACTURE SYSTEM INDICATES GONDWANA WAS UNDER UNIFORM TENSION

HOTSPOTS ON TESSELLATION

NOTE SYMMETRY OF STRESS TESSELLATION ACROSS GONDWANA

INITIAL GEOMETRY OF GONDWANA DETERMINED BEST ORIENTATION OF TESSELLATION TO

ACHIEVE MINIMUM FRACTURE LENGTH

AND THEREFORE LEAST WORK

HOTSPOTS ON TESSELLATION

AFRICAN GEOID ANOMALYSYMMETRICAL TO FRACTURES

WHEN GONDWANA IS RESTORED TO TRIASSIC POSITION

HOTSPOTS ON TESSELLATION

GONDWANA SPREAD OUTWARD DOWN GEOID GRADIENT

SEE ANDERSON, 1982

GONDWANA STALLED ON MANTLE FRAMEWORKGONDWANA STALLED ON MANTLE FRAMEWORKINSULATED UNDERLYING MANTLEINSULATED UNDERLYING MANTLE

THERMAL EXPANSION OF MANTLE DROVE UPLIFT THERMAL EXPANSION OF MANTLE DROVE UPLIFT AND UNIFORM TENSION IN GONDWANAAND UNIFORM TENSION IN GONDWANA

FRACTURE TESSELLATION OCCURRED AT CLIMAX FRACTURE TESSELLATION OCCURRED AT CLIMAX OF UPLIFT, IN EARLY TRIASSICOF UPLIFT, IN EARLY TRIASSIC

FRACTURES LATER SEPARATED AS REQUIRED BY FRACTURES LATER SEPARATED AS REQUIRED BY PLATE TECTONICS, DRIVING DECOMPRESSION PLATE TECTONICS, DRIVING DECOMPRESSION

MELTING MELTING