Sorong Fault
Encyclopedia
Sorong fault also is an active, broad zone of inferred left lateral shear at the triple junction
of the Australian plate, Eurasian plate
, and Pacific plate
s, where many plate fragments exist, such as the Philippine Sea Plate, Bird's Head Plate
, Halmahera Plate
and the Molucca Sea Plate
. It has been implicated in numerous large earthquakes. It is one of the 2 major faults created by the Australian and Pacific plate convergence, the other being the Ramu-Markham Fault zone.
and runs towards New Guinea
. It marks the boundary between Halmahera plate and Bird's Head Plate.
The Sorong fault system has been documented to extend westward more than 500 miles (800 km) from Teluk Sarera
to Kepulauan Banggai.
-Tertiary continental and arc rocks/ophiolitic rocks.
are being detached and translated westward in this shear zone until they collide with the eastern margin of Eurasia (Sundaland
) in the region of Sulawesi Island. However, the details of terrane translation
, amalgamation, and docking remain poorly documented at this time. In particular, the timing of events is very poorly constrained, with estimates for the commencement of the SFZ ranging from early Miocene
or older to Pleistocene
. Investigations in the 1990s of the SFZ and the adjacent regions of Sulawesi and Irian Jaya (Indonesian New Guinea), including fieldwork in several of the SFZ island-terranes (Waigeo Island, Halmahera
, Bacan
, Obi Islands
, and Sula islands
), suggest a less mobilist interpretation of the region than previous reconstructions. SFZ did not begin to develop in its present form before the late Miocene.
Triple junction
A triple junction is the point where the boundaries of three tectonic plates meet. At the triple junction a boundary will be one of 3 types - a ridge, trench or transform fault - and triple junctions can be described according to the types of plate margin that meet at them...
of the Australian plate, Eurasian plate
Eurasian Plate
The Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia , with the notable exceptions of the Indian subcontinent, the Arabian subcontinent, and the area east of the Chersky Range in East Siberia...
, and Pacific plate
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million square kilometres, it is the largest tectonic plate....
s, where many plate fragments exist, such as the Philippine Sea Plate, Bird's Head Plate
Bird's Head Plate
The Bird's Head Plate is a minor tectonic plate incorporating the Bird's Head Peninsula at the western end of the island of New Guinea. Hillis & Müller consider it to be moving in unison with the Pacific Plate. Bird considers it to be unconnected to the Pacific Plate. The plate is separating from...
, Halmahera Plate
Halmahera Plate
Halmahera Plate has recently been postulated to be a microplate within the Molucca Sea Collision Zone of eastern Indonesia.-Regional tectonics:...
and the Molucca Sea Plate
Molucca Sea Plate
-Earlier theory:The Molucca Sea Plate was theorised to be a small tectonic plate carrying northern Sulawesi, the Molucca Sea and a portion of the Banda Sea in a region littered with numerous small plates. The theory suggested a subduction zone lies along its northern border with the Sunda Plate...
. It has been implicated in numerous large earthquakes. It is one of the 2 major faults created by the Australian and Pacific plate convergence, the other being the Ramu-Markham Fault zone.
Location
The Sorong fault begins around SulawesiSulawesi
Sulawesi is one of the four larger Sunda Islands of Indonesia and is situated between Borneo and the Maluku Islands. In Indonesia, only Sumatra, Borneo, and Papua are larger in territory, and only Java and Sumatra have larger Indonesian populations.- Etymology :The Portuguese were the first to...
and runs towards New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
. It marks the boundary between Halmahera plate and Bird's Head Plate.
The Sorong fault system has been documented to extend westward more than 500 miles (800 km) from Teluk Sarera
Cenderawasih Bay
Cenderawasih Bay , also Teluk Sarera , formerly Geelvink Bay is a large bay in northern Province of Papua and West Papua, New Guinea, Indonesia, at . The Dutch name comes after a Dutch ship and family called Geelvinck...
to Kepulauan Banggai.
Geology
The fault zone juxtaposes MesozoicMesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
-Tertiary continental and arc rocks/ophiolitic rocks.
Plate Evolution
It is widely believed that fragments of the northern Australian continental margin in New GuineaNew Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
are being detached and translated westward in this shear zone until they collide with the eastern margin of Eurasia (Sundaland
Sundaland
Sundaland is a biogeographical region of Southeastern Asia which encompasses the areas of the Asian continental shelf that was exposed during the last ice age. It included the Malay Peninsula on the Asian mainland, as well as the large islands of Borneo, Java, and Sumatra and their surrounding...
) in the region of Sulawesi Island. However, the details of terrane translation
Translation
Translation is the communication of the meaning of a source-language text by means of an equivalent target-language text. Whereas interpreting undoubtedly antedates writing, translation began only after the appearance of written literature; there exist partial translations of the Sumerian Epic of...
, amalgamation, and docking remain poorly documented at this time. In particular, the timing of events is very poorly constrained, with estimates for the commencement of the SFZ ranging from early Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
or older to Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
. Investigations in the 1990s of the SFZ and the adjacent regions of Sulawesi and Irian Jaya (Indonesian New Guinea), including fieldwork in several of the SFZ island-terranes (Waigeo Island, Halmahera
Halmahera
Halmahera is the largest island in the Maluku Islands. It is part of the North Maluku province of Indonesia.Halmahera has a land area of 17,780 km² and a population in 1995 of 162,728...
, Bacan
Bacan
Bacan refers to a group of islands in the Maluku Islands of Indonesia and to that group's largest island. The islands are mountainous and forested. The islands lie south of Ternate and west of Halmahera's southernmost arm...
, Obi Islands
Obi Islands
The Obi Islands are a group of islands in the Indonesian province of Maluku. They lie north of Buru and Ceram....
, and Sula islands
Sula Islands
The Sula Islands are a group of islands in North Maluku in Indonesia. Its three main islands are Mangole, Sanae and Taliabu, with smaller islands Lifamatola and Seho. It is administered as Kepulauan Sula Regency...
), suggest a less mobilist interpretation of the region than previous reconstructions. SFZ did not begin to develop in its present form before the late Miocene.