self-organized breakup of gondwana: an argument against the deep mantle plume paradigm jim sears...
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SELF-ORGANIZED BREAKUP OF GONDWANA:AN ARGUMENT AGAINST THE DEEP MANTLE
PLUME PARADIGM
Jim SearsUniversity of Montana, USA
HEARD ISLAND HOT SPOT
THE DEEP MANTLE PLUME PARADIGM AN INTEGRAL COMPONENT OF PLATE TECTONICS SINCE J.T. WILSON (1963) AND W.J. MORGAN (1981)
PLUMES ARE RANDOMLY GENERATED ALONG THE CORE-MANTLE BOUNDARY
PLUME OUTBREAKS INITIATE CONTINENTAL BREAKUP
AFRICA
SOUTHAMERICA
INDIA
ARABIA
ANTARCTICA
AU
STR
ALI
A
N Z
HOWEVER, BREAKUP OF GONDWANA WAS NOT
RANDOM - IT WAS HIGHLY ORGANIZED AND SELF-
ORGANIZED
FLO
RID
A
AFRICA
SOUTHAMERICA
INDIA
ARABIA
ANTARCTICA
AU
STR
ALI
A
N Z
THESE MAJOR GONDWANA
FRACTURE POLYGONS RIGOROUSLY OBEY EULER’S THEOREM
FOR CONVEX POLYTOPES
FLO
RID
A
AFRICA
INDIA
ARABIA
AU
STR
ALI
A
N Z
FLO
RID
A
NAMELY, TO TILE A SPHERE WITH 12 OR MORE PLATES, 12 MUST HAVE 5-
FOLD SYMMETRY AT VERTICES OF
ICOSAHEDRON
Euler’s formula relating faces (F), vertices (V ), and edges (E) of a convex polytope (F + V = E + 2)
ICOSAHEDRAL ARRANGEMENTS
Zandi & Reguera, 2005
PATTERN MINIMIZES TOTAL FRACTURE LENGTHAND THEREFORE MINIMIZES WORK
FUNCTION OF STRENGTH OF GONDWANA SHELL
ETHIOPIAN
38 Ma
LARGE IGNEOUS PROVINCES
DEEP MANTLE PLUMES?
65 Ma
110 Ma
134 Ma
144 Ma
183 Ma
183 Ma
205 Ma
AFRICA
SOUTHAMERICA
ARABIA
ANTARCTICA
AU
STR
ALI
A
N Z
FLO
RID
A
INDIA
3-ARMED RIFTSMANY ARE 2600 KM
2600 KM
16 EDGES,>20,000 KM
PP
H
H
HH
H
P
LARGE IGNEOUS PROVINCES ERUPT DIACHRONOUSLY ALONG FRACTURE
PATTERN
DEPEND ON PLATE TECTONICS TO OPENFRACTURES TO INDUCE DECOMPRESSION
MELTING
CONCORDANCE OF A FAMILY OF HOT SPOTS WITH FRACTURE TESSELLATION IMPLIES PLATE
WAS STATIONARY DURING THEIR FORMATION
HOTSPOTS ON TESSELLATION
YELLOW STRESS TESSELLATION IS DUAL OF FRACTURE TESSELLATION:
THEY CROSS ONE ANOTHER ORTHOGONALLY
HOTSPOTS ON TESSELLATION
NOTE PERFECT SYMMETRY OF STRESS TESSELLATION ACROSS
GONDWANA
HOTSPOTS FAVOR CENTERS
EXPANSION OF GONDWANA LEADS TO FRACTURES
HOTSPOTS ON TESSELLATION
NOTE PERFECT SYMMETRY OF STRESS TESSELLATION ACROSS
GONDWANA
HOTSPOTS FAVOR CENTERS
INITIAL GEOMETRY OF GONDWANA DETERMINED BEST ORIENTATION OF TESSELLATION TO
ACHIEVE MINIMUM FRACTURE LENGTH
HOTSPOTS ON TESSELLATION
AFRICAN GEOID ANOMALYSYMMETRICAL TO FRACTURES
WHEN GONDWANA IS RESTORED TO TRIASSIC POSITION