Recent mega-tsunamis in the Shark Bay, Pilbara, and ...€¦ · Recent mega-tsunamis in the Shark...
1
Recent mega-tsunamis in the Shark Bay, Pilbara, and Kimberley areas of Western Australia Geological Survey of Western Australia www. mp.wa.gov.au d Phillip Playford – Geological Survey ofWestern Australia 5. Photo taken in 1910 ( ) and 2010 ( ) at Cape Inscription, showing large blocks of calcrete at the foot of the cliff, and a layer of calcrete at the top.The large left right blocks, probably deposited by a mega-tsunami, have not moved during the past 100 years, despite many tropical cyclones having passed by during that time. 1. Map showing localities between the Zuytdorp Cliffs and Legendre Island where boulder deposits were emplaced by mega-tsunamis several thousand years ago. 8. Boulder of calcrete encrusted by oysters on Barrow Island. Karst holes on the boulder pre-date growth of the oysters. 7.Boulder deposit at Barrow Island, showing eroded boulders of calcrete, about 8 m above sea level, thought to have been deposited there by a mega-tsunami. 6. Air photo of part of the west coast of Barrow Island showing the indented coast, thought to have been sculpted by successive mega-tsunamis. 3. Aerial view of imbricate calcrete blocks beside the west coast of Dirk Hartog Island. These blocks, each weighing up to 700 tonnes, slope away from the coast and were oriented by the powerful backwash following the tsunami. 2. ‘ ’ The Block , south of Cape Inscription, Dirk Hartog Island, which weighs about 700 tonnes.It was thrown about 15 m above sea level and 120 m behind the shoreline cliff by a mega-tsunami. 4.Several of the imbricate calcrete blocks, sloping east, away from the coast, as a result of the backwash after the tsunami. 10.The northwest end of Legendre Island, showing large calcrete blocks, thought to have been deposited by a mega-tsunami about 2900 years ago, resting on a strongly karstified calcrete surface. 11.Part of the northwest coast of Legendre Island, showing erosion of the cliff face by a mega-tsunami, with many large blocks of limestone scattered over the land surface behind the cliff. 9. Geological map of the Burrup Peninsula area, showing the location of Legendre Island, which was struck by a mega-tsunami about 2900 years ago. 13.Column of sandstone in a silicified fault zone near Cape Domett in the Kimberley, with two boulders of siliceous sandstone perched near the top, thought to have been carried there by a mega-tsunami. DAMPIER KARRATHA 116°45' 116°30' 20°30' 20°45' 5 km PEP1503 BURRUP PENINSULA DAMPIER ARCHIPELAGO 20 m 20 m 20 m Marine and coastal sand Eolian limestone and calcrete Alluvium–colluvium Road Town Precambrian rocks Made ground Quaternary LNG Plant Legendre Island Salt evaporation ponds 12. Map of the Kimberley showing the intricately sculpted nature of the coast thought to have resulted from the impacts of many mega-tsunamis, over millions of years. 14. Radiocarbon dates of oysters and other fossils in tsunami deposits. Locality Description C14 date (in years) Dirk Hartog Island Clump of coral over red sand 4004 ± 41 BP Tridacna shell over red sand 38 522 ± 605 BP Legendre Island Block of oyster shells 2895 ± 35 BP Block of oyster shells 3777 ± 40 BP Barrow Island Oyster shells on block of calcrete Oyster shells on block of calcrete Block of oyster shells Block of oyster shells Oyster shells on block of calcrete Oyster shells on block of calcrete 4652 ± 28 BP Oyster shells on block of calcrete August 2013 126° PEP1488a2 128° 14° 16° 100 km THE KIMBERLEY Wyndham Kununurra Cape Domett Dirk Hartog Island Legendre Island Koks Island KARRATHA CARNARVON PORT HEDLAND 118° 114° 22° 26° 150 km INDIAN OCEAN PEP1459 Bernier Island Dorre Island Point Quobba Zuytdorp Barrow Island Cliffs
Transcript of Recent mega-tsunamis in the Shark Bay, Pilbara, and ...€¦ · Recent mega-tsunamis in the Shark...
Recent mega-tsunamis in the Shark Bay, Pilbara,and Kimberley areas of Western Australia
Geological Survey ofWestern Australiawww. mp.wa.gov.aud
Phillip Playford – Geological Survey of Western Australia
5. Photo taken in 1910 ( ) and 2010 ( ) at Cape Inscription, showing large blocks of calcrete at the foot of the cliff, and a layer of calcrete at the top. The largeleft rightblocks, probably deposited by a mega-tsunami, have not moved during the past 100 years, despite many tropical cyclones having passed by during that time.
1. Map showing localities betweenthe Zuytdorp Cliffs and LegendreIsland where boulder depositswere emplaced by mega-tsunamisseveral thousand years ago.
8. Boulder of calcrete encrusted by oysters on Barrow Island. Karst holes on theboulder pre-date growth of the oysters.
7. Boulder deposit at Barrow Island, showing eroded boulders of calcrete, about 8 mabove sea level, thought to have been deposited there by a mega-tsunami.
6. Air photo of part of the west coast of Barrow Island showing the indented coast,thought to have been sculpted by successive mega-tsunamis.
3. Aerial view of imbricate calcrete blocks beside the west coast of Dirk Hartog Island.These blocks, each weighing up to 700 tonnes, slope away from the coast and wereoriented by the powerful backwash following the tsunami.
2. ‘ ’The Block , south of Cape Inscription, Dirk Hartog Island, which weighs about700 tonnes. It was thrown about 15 m above sea level and 120 m behind theshoreline cliff by a mega-tsunami.
4. Several of the imbricate calcrete blocks, sloping east, away from the coast,as a result of the backwash after the tsunami.
10. The northwest end of Legendre Island, showing large calcrete blocks, thought tohave been deposited by a mega-tsunami about 2900 years ago, resting on a stronglykarstified calcrete surface.
11. Part of the northwest coast of Legendre Island, showing erosion of the cliff faceby a mega-tsunami, with many large blocks of limestone scattered over the landsurface behind the cliff.
9. Geological map of the Burrup Peninsula area, showing the location ofLegendre Island, which was struck by a mega-tsunami about 2900 years ago.
13. Column of sandstone in a silicified fault zone near Cape Domett in the Kimberley,with two boulders of siliceous sandstone perched near the top, thought to have beencarried there by a mega-tsunami.
DAMPIER
KARRATHA
116°45'116°30'
20°30'
20°45'
5 km
PEP1503
BURRUPPENINSULA
DAMPIE
RARCHIP
ELAGO
20 m
20 m
20 m
Marine and coastal sand
Eolian limestone andcalcrete
Alluvium–colluvium
Road
TownPrecambrian rocks
Made ground
Quate
rnary
LNG Plant
Legendre Island
Salt evaporation ponds
12. Map of the Kimberley showing the intricately sculpted nature of the coastthought to have resulted from the impacts of many mega-tsunamis, overmillions of years.
14. Radiocarbon dates of oysters and other fossils in tsunami deposits.
Locality Description C14 date(in years)
Dirk HartogIsland
Clump of coral over red sand 4004 ± 41 BP
Tridacna shell over red sand 38 522 ± 605 BP
LegendreIsland
Block of oyster shells 2895 ± 35 BP
Block of oyster shells 3777 ± 40 BP
BarrowIsland
Oyster shells on block of calcrete
Oyster shells on block of calcrete
Block of oyster shells
Block of oyster shells
Oyster shells on block of calcrete
Oyster shells on block of calcrete 4652 ± 28 BP
Oyster shells on block of calcrete
August 2013
126°
PEP1488a2
128°
14°
16°
100 km
THE KIMBERLEY
Wyndham
Kununurra
Cape Domett
DirkHartogIsland
Legendre Island
Koks Island
KARRATHA
CARNARVON
PORTHEDLAND
118°114°
22°
26°
150 km
INDIANOCEAN
PEP1459
Bernier Island
Dorre Island
Point Quobba
Zuytdorp
Barrow Island
Cliffs
