Misplaced Pages

#182817

76-704: The Narryer Gneiss Terrane is a geological complex in Western Australia that is composed of a tectonically interleaved and polydeformed mixture of granite , mafic intrusions and metasedimentary rocks in excess of 3.3 billion years old, with the majority of the Narryer Gneiss Terrane in excess of 3.6 billion years old. The rocks have experienced multiple metamorphic events at amphibolite or granulite conditions, resulting in often complete destruction of original igneous or sedimentary ( protolith ) textures . Importantly, it contains

152-683: A capacity of 23,200 cubic metres per day (146,000 barrels per day) until its closure in 2021, producing most of the state's petrol and diesel. Kwinana also hosts alumina and nickel processing plants, port facilities for grain and other bulk exports, and support industries for mining and petroleum such as heavy and light engineering, and metal fabrication. Shipbuilding (e.g. Austal ) and associated support industries are found at nearby Henderson , just north of Kwinana. Significant secondary industries include cement and building product manufacturing, flour milling, food processing, animal feed production, automotive body building and printing. Western Australia has

228-527: A comparative advantage in resource extraction and processing. As a consequence: In 2019 Western Australia's overseas exports accounted for 46% of the nation's total. The state's major export commodities included iron-ore, petroleum, gold, alumina , nickel, wheat, copper, lithium, chemicals and mineral sands. Western Australia is the world's largest iron-ore producer (34% of the world's total), and extracts 66% (6.9% of world production) of Australia's 306 tonnes (9.8 million troy ounces) of gold in 2022. It

304-459: A further 1,196 species currently recognised but unpublished. They occur within 1,543 genera from 211 families ; there are also 1,276 naturalised alien or invasive plant species, more commonly known as weeds. In the southwest region are some of the largest numbers of plant species for its area in the world. Western Australia's ecoregions include the sandstone gorges of the Kimberley on

380-626: A high degree of deformation around the margins, and preserves an amphibolite facies metamorphic assemblage. The gneiss is pervasively shot through with pegmatite veins. Within the low-strain zones, the Dugel Gneiss exists as a medium-grained leucocratic metagranite with phenocrysts of K-feldspar which has recrystallized into granulite facies. The rock is greasy-looking with annealed quartz and feldspar , and syn-granulite facies leucosomes cutting across metamorphic banding, and subsequently deformed by later metamorphism . The Dugel Gneiss

456-403: A lack of storage and refrigeration facilities favour live animals over imports of processed meat. About half of Australia's live cattle exports come from Western Australia. Resource sector growth in recent years has resulted in significant labour and skills shortages, leading to recent efforts by the state government to encourage interstate and overseas immigration. According to the 2006 census,

532-467: A mixed massive or mixed sulfide-silicate 'matrix' of pentlandite , chalcopyrite , pyrrhotite and/or pyrite are formed, occasionally with cobaltite and platinum-tellurium sulfides. These deposits are formed by melt immiscibility between sulfide and silicate melts in a sulfur-saturated magma. They are not strictly a cumulate rock, as the sulfide is not precipitated as a solid mineral, but rather as immiscible sulfide liquid. However, they are formed by

608-517: A result, the South West region of the state has a higher concentration of rare, threatened or endangered flora and fauna than many areas of Australia, making it one of the world's biodiversity "hot spots". Large areas of the state's wheatbelt region have problems with dryland salinity and the loss of fresh water. The southwest coastal area has a Mediterranean climate . It was originally heavily forested, including large stands of karri , one of

684-553: A scientific paper, General view of the botany of the vicinity of Swan River . It discusses the vegetation of the Swan River Colony . Europeans began to settle permanently in 1826 when Albany was claimed by Britain to forestall French claims to the western third of the continent. Perth was founded as the Swan River Colony in 1829 by British and Irish settlers, though the outpost languished. Its officials eventually requested convict labour to augment its population. By

760-628: A significant fishing industry. Products for local consumption and export include western rock lobsters , prawns, crabs, shark and tuna, as well as pearl fishing in the Kimberley region of the state. Processing is conducted along the west coast. Whaling was a key marine industry but ceased at Albany in 1978. Western Australia has the world's biggest plantations of both Indian sandalwood (northern WA) and Australian sandalwood (semi-arid regions), which are used to produce sandalwood oil and incense . The WA sandalwood industry provides about 40% of

836-490: Is 1,862 km (1,157 mi). There are 20,781 km (12,913 mi) of coastline, including 7,892 km (4,904 mi) of island coastline. The total land area occupied by the state is 2.5 million km (970 thousand sq mi). The bulk of Western Australia consists of the extremely old Yilgarn craton and Pilbara craton which merged with the Deccan Plateau of India, Madagascar and

SECTION 10

#1732765238183

912-450: Is a major world producer of bauxite, which is processed into alumina at four refineries providing 11% of total world production. Until 2020 diamonds were extracted from the world's largest diamond mine in the far north Kimberley region. Coal mined at Collie is the main fuel for baseload electricity generation in the state's south-west. Agricultural production in WA is a major contributor to

988-469: Is attributed by historians as an important factor driving the state's population and economic growth. Following a campaign led by Forrest, electors of the colony of Western Australia voted in favour of federation with the five other Australian colonies, resulting in Western Australia officially becoming a state on 1 January 1901. Western Australia is bounded to the east by longitude 129°E,

1064-786: Is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Australia is Australia’s largest state, with a land area of 2,527,013 square kilometres (975,685 sq mi), and is also the second-largest subdivision of any country on Earth, surpassed only by the Sakha Republic in eastern Russia, and formerly Northwest Territories in Canada, before

1140-504: Is considered to be intruded into the older Meeberrie Gneiss, possibly as sheets or sills , but most contacts are overprinted by ductile metamorphic banding or mylonite zones. The Meeberrie Gneiss is a generally ductilely deformed banded gneiss of monzogranitic composition, and its protolith is interpreted as a set of monzogranite sills or lopolithic intrusions. The gneiss is heavily banded by layers of amphibolite-K-feldspar-quartz of varying grainsize, plus networks of pegmatite veins. Most

1216-573: Is currently tilted 10 degrees away from the South Pole towards Western Australia, allowing for aurora australis displays as far north as Geraldton . Western Australia is home to around 630 species of birds (depending on the taxonomy used). Of these around 15 are endemic to the state. The best areas for birds are the southwestern corner of the state and the area around Broome and the Kimberley. The Flora of Western Australia comprises 10,162 published native vascular plant species, along with

1292-666: Is generally formed during pyroxene fractionation at low pressures, where chromium is rejected from the pyroxene crystals. These oxide layers form laterally continuous deposits of rocks containing in excess of 50% oxide minerals. When oxide minerals exceed 90% of the bulk of the interval the rock may be classified according to the oxide mineral, for example magnetitite , ilmenitite or chromitite . Strictly speaking, these would be magnetite orthocumulate, ilmenite orthocumulate and chromite orthocumulates. Sulfide mineral cumulates in layered intrusions are an important source of nickel , copper , platinum group elements and cobalt . Deposits of

1368-431: Is inappropriate to describe them according to this convention. Cumulate rocks, because they are fractionates of a parental magma, should not be used to infer the composition of a magma from which they are formed. The chemistry of the cumulate itself can inform on the residual melt composition, but several factors need to be considered. The chemistry of a cumulate can inform upon the temperature, pressure and chemistry of

1444-404: Is made of the accumulated minerals will not have the same composition as the magma. In the above example, the cumulate of anorthite + enstatite is rich in calcium and magnesium, and the melt is depleted in calcium and magnesium. The cumulate rock is a plagioclase-pyroxene cumulate (a gabbro) and the melt is now more felsic and aluminous in composition (trending towards andesite compositions). In

1520-737: Is more fraught with problems. These methods have their drawbacks, primarily that they must all make certain assumptions which rarely hold true in nature. The foremost problem is that in large ultramafic intrusions, assimilation of wall rocks tends to alter the chemistry of the melt as time progresses, so measuring groundmass compositions may fall short. Mass balance calculations will show deviations from expected ranges, which may infer assimilation has occurred, but then further chemistry must be embarked upon to quantify these findings. Secondly, large ultramafic intrusions are rarely sealed systems and may be subject to regular injections of fresh, primitive magma, or to loss of volume due to further upward migration of

1596-504: Is now known as Cape Inscription, Dirk Hartog Island . For the rest of the 17th century, other Dutch and British navigators encountered the coast of what Abel Tasman named New Holland in 1644, usually unintentionally as demonstrated by the many shipwrecks along the coast of ships that deviated from the Brouwer Route (because of poor navigation and storms). By the late 18th century, British and French sailors had begun to explore

SECTION 20

#1732765238183

1672-631: Is strongly deformed, but least-deformed areas show a relict porphyritic to equigranular texture. The Manfred Complex is a heavily attenuated and discontinuous series of ultramafic to mafic cumulates contained within a matrix or wall-rocks of mixed Dugel and Meeberrie Gneisses. The rock types are primarily pyroxene gabbro to amphibolite, with rare serpentinised peridotite and dunite , occasionally containing relict igneous or metamorphic olivine . These boudins of material range from centimetre-scale to ~100m thick and one kilometre long and, based on their position within anticlines and synclines in

1748-400: Is the northern tropical regions. The Kimberley has an extremely hot monsoonal climate with average annual rainfall ranging from 500 to 1,500 millimetres (20–60 in), but there is a very long almost rainless season from April to November. Eighty-five percent of the state's runoff occurs in the Kimberley, but because it occurs in violent floods and because of the insurmountable poverty of

1824-543: Is to measure groundmass chemistry, but that chemistry is problematic or impossible to sample. Otherwise, complex calculations of averaging cumulate layers must be utilised, which is a complex process. Alternatively, the magma composition can be estimated by assuming certain conditions of magma chemistry and testing them on phase diagrams using measured mineral chemistry. These methods work fairly well for cumulates formed in volcanic conditions (i.e.; komatiites ). Investigating magma conditions of large layered ultramafic intrusions

1900-641: The Group Settlement Scheme of the 1920s, which encouraged farmers to settle the southwest—increased awareness of Australia's western third as a destination for colonists. Led by immigrants from the British Isles, Western Australia's population developed at a faster rate during the twentieth century than it had previously. After World War II , both the eastern states and Western Australia received large numbers of Italians , Croatians and Macedonians . Despite this, Britain has contributed

1976-588: The Kaapvaal and Zimbabwe cratons of Southern Africa, in the Archean Eon to form Ur , one of the oldest supercontinents on Earth (3 – 3.2  billion years ago). In May 2017, evidence of the earliest known life on land may have been found in 3.48-billion-year-old geyserite and other related mineral deposits (often found around hot springs and geysers ) uncovered in the Pilbara craton. Because

2052-571: The Mount Narryer area, are interpreted to have intruded subparallel to bedding and are now strung out by shearing . The Manfred Complex is interpreted to represent an early Archaean mafic to ultramafic layered intrusion which has been disaggregated. This disaggregation is partly tectonic, but in some areas evidence suggests that this was mostly achieved by the intrusion of the Dugel and Meeberrie gneisses as sills or sheets. Geochronology on

2128-496: The Swan River Colony with Perth as its capital in 1829. The Western Australian gold rushes of the late 19th century resulted in a significant population influx. The colony was granted responsible government in 1890, the last of the Australian colonies to become self-governing, and federated with the other colonies in 1901. Western Australia's mining sector is a key driver of the state economy . The late 20th century saw

2204-555: The Wheatbelt and temperate southern coastal regions, pastoralism in marginal grassland areas, forestry in the south-west and fishing (including pearling and, historically, whaling ). Western Australia has a geological history dating back to 4.4 billion years ago when Hadean zircons were formed. The earliest direct known life on land, known as stromatolites , started to be created by microbes at around 3.48 billion years ago. The first human inhabitants of Australia arrived from

2280-557: The Yarlarweelor Gneiss which abuts to Nabberu Basin metamorphic sequences of the Bryah-Padbury Basins , where it is present as discontinuous slivers of metamorphic rocks , pelites , metaconglomerates and gneisses caught up within regional strike-slip oblique thrust faults . The Narryer Gneiss in this far-eastern region may form the basement to the 2.0-1.8 billion year old Proterozoic rocks, and

2356-814: The Yilgarn Craton , following an event at ~3350 Ma of amphibolite facies, resulting in widespread re-equilibration of geochronometers, preceded by a deformation loosely constrained to ~3680 Ma and another predating the Meeberrie Gneiss and postdating the Manfred Complex, between 3680 and 3730 Ma. Older structural grain is preserved in areas of low stress in subsequent deformations; the 2700 to 2600 Ma Yilgarn Craton associated deformation has overprinted most other deformations, resulting in rotation of previous structures into parallelism with NE-trending upright folds and metamorphic banding. Proximal to

Narryer Gneiss Terrane - Misplaced Pages Continue

2432-489: The tallest trees in the world. This agricultural region is one of the nine most bio-diverse terrestrial habitats, with a higher proportion of endemic species than most other equivalent regions. Thanks to the offshore Leeuwin Current , the area is one of the top six regions for marine biodiversity and contains the most southerly coral reefs in the world. Average annual rainfall varies from 300 millimetres (12 in) at

2508-577: The unconformity surface may be preserved within the thrust sheets. The Narryer Gneiss Terrane is divided into four major rock sequences (Myers 1990); the Dugel Gneiss, Meeberrie Gneiss, Manfred Complex, and unassigned polydeformed leucocratic gneisses and metasediments. The Dugel Gneiss is syenogranitic or monzogranitic in composition and this is interpreted as the protolith. The gneiss is leucocratic, with only minor amounts of biotite and muscovite . The rock exhibits variable intensity of metamorphic banding which may include grain size variations, and has

2584-576: The 1890s around Kalgoorlie . In 1887, a new constitution was drafted, providing for the right of self-governance of European Australians, and in 1890, the act granting self-government to the colony was passed by the British Parliament . John Forrest became the first Premier of Western Australia . In 1896, after discoveries of gold at Coolgardie and Kalgoorlie , the Western Australian Parliament authorised

2660-433: The 2016 census, 75.2% of inhabitants spoke only English at home, with the next most common languages being Mandarin (1.9%), Italian (1.2%), Vietnamese (0.8%), Cantonese (0.8%) and Tagalog (0.6%). According to the 2021 census, Christianity is the major religious affiliation in WA, followed by 41.1% of its population. In 1971, Christianity was followed by 85.5% of the population and it has been declining since, while

2736-948: The Manfred Complex places its age at around 3.73 billion via Pb -Pb on zircon. This makes it the oldest recognised intrusive rock on the Earth, containing the oldest known igneous textures and mineral assemblages. Metasedimentary rocks from within the Narryer Gneiss terrane account for about 10% of the outcrop and are variably deformed but uniformly of at least amphibolite grade metamorphism. The most abundant rock types are quartzite and banded iron formation , with subordinate metamorphic gneisses, metaconglomerates and pelitic to semi-pelitic quartz-muscovite schists . The conglomerates are primarily orthoquartzite monomict vein- pebble conglomerates, or polymict pebble conglomerates. In low-strain zones they preserve graded bedding, cross-bedding and heavy mineral-rich horizons. These rocks provide

2812-547: The Narryer Gneiss Terrane of the Western Gneiss Belt of the Yilgarn craton is reproduced after A. F. Trendall (1991); Fletcher, I.R., D.K. Paul, and A.F. Trendall. (1990) Sm‐Nd and geochemical characteristics of metasedimentary rocks at Mt Narryer, Western Australia . Australian Journal of Earth Sciences 39:67-78. Western Australia Western Australia (WA) is the westernmost state of Australia . It

2888-590: The Proterozoic orogens and thrust belts, the gneiss belt has become variably overprinted by later deformations. In the Bryah-Padbury Basin fold-thrust belt, Yarlarweelor Gneiss rafts exist as undeformed thrust plates of pelitic schist bounded by discrete mylonite zones, as well as deformed heavily overprinted gneiss blocks caught up within shear zones, some of which appear to preserve the unconformity surface. A simplified sequence of events known from

2964-587: The Western Australian coast. The Baudin expedition of 1800–03 included the coast of Western Australia and resulted in the Freycinet Map of 1811 , the first published map featuring the full outline of Australia. The name New Holland remained in popular and semi-official use until at least the mid-1850s; that is, it was in use for about 206 years in comparison to the name Australia which to date has been in use for about 195 years. The origins of

3040-405: The above example, the plagioclase and pyroxene need not be pure end-member compositions (anorthite-enstatite), and thus the effect of depletion of elements can be complex. The minerals can be precipitated in any ratio within the cumulate; such cumulates can be 90% plagioclase:10% enstatite, through to 10% plagiclase:90% enstatite and remain a gabbro. This also alters the chemistry of the cumulate, and

3116-467: The bulk of age determinations from the Narryer Gneiss Terrane from detrital zircons, with the bulk of readings bracketing 3.5 to 3.75 billion years old, 3.35 to 3.45 billion years old, and a population of 4.1 to 4.2 billion years, with outliers of up to 4.4 billion years old. The Narryer Gneiss Terrane has undergone many high-grade polyphase deformation events, with the most notable being at 2600 to 2700 Ma associated with granite- greenstone magmatism in

Narryer Gneiss Terrane - Misplaced Pages Continue

3192-805: The coast around the Margaret River wine-growing area. Going east along the Southern Ocean coast is the Goldfields-Esperance region, including the Esperance mallee and the Coolgardie woodlands inland around town of Coolgardie . Deserts occupy the interior, including the Great Sandy-Tanami desert , Gibson Desert , Great Victoria Desert , and Nullarbor Plain . In 1831 Scottish botanist Robert Brown produced

3268-685: The coast of Western Australia. On 7 March 1831 it was transferred to the control of the Swan River Colony, and named Albany in 1832. In 1829 the Swan River Colony was established on the Swan River by Captain James Stirling . By 1832, the British settler population of the colony had reached around 1,500, and the official name of the colony was changed to Western Australia on 6 February that year. The two separate townsites of

3344-730: The coastal plains, in some cases forming a sharp escarpment (as with the Darling Range/ Darling Scarp near Perth). The extreme age of the landscape has meant that the soils are remarkably infertile and frequently laterised . Even soils derived from granitic bedrock contain an order of magnitude less available phosphorus and only half as much nitrogen as soils in comparable climates in other continents. Soils derived from extensive sandplains or ironstone are even less fertile, nearly devoid of soluble phosphate and deficient in zinc , copper, molybdenum and sometimes potassium and calcium . The infertility of most of

3420-425: The colony developed slowly into the port city of Fremantle and the state's capital, Perth . York was the first inland settlement in Western Australia, situated 97 kilometres (60 mi) east of Perth and settled on 16 September 1831. York was the staging point for early explorers who discovered the rich gold reserves of Kalgoorlie. Population growth was very slow until significant discoveries of gold were made in

3496-471: The creation of Nunavut. It is also the largest proper subnational entity, being a state rather than a territory or an autonomous region. Western Australia has a diverse range of climates, including tropical conditions in the Kimberley , deserts in the interior (including the Great Sandy Desert , Little Sandy Desert , Gibson Desert , and Great Victoria Desert ) and a Mediterranean climate on

3572-501: The crystallisation of oxide minerals which are invariably a form of spinel . This can happen due to fractional enrichment of the melt in iron , titanium or chromium . These conditions are created by the high-temperature fractionation of highly magnesian olivine or pyroxene, which causes a relative iron-enrichment in the residual melt. When the iron content of the melt is sufficiently high, magnetite or ilmenite crystallise and, due to their high density, form cumulate rocks. Chromite

3648-525: The depletions of the residual melt. It can be seen that the effect on the composition of the residual melt left behind by the formation of the cumulate is dependent on the composition of the minerals which precipitate, the number of minerals which co-precipitate at the same time, and the ratio of the minerals which co-precipitate. In nature, cumulates usually form from 2 mineral species, although ranges from 1 to 4 mineral species are known. Cumulate rocks which are formed from one mineral alone are often named after

3724-432: The development of the state's significant iron ore mining industry – the world's largest – as well as primarily offshore petroleum and natural gas resources . Gold mining retains a significant presence and many other mineral commodities are mined, with Perth being a major centre for associated services. Outside of mining, primary industry is the other significant contributor to the state's economy, including agriculture in

3800-569: The edge of the Wheatbelt region to 1,400 millimetres (55 in) in the wettest areas near Northcliffe , but from November to March, evaporation exceeds rainfall, and it is generally very dry. Plants are adapted to this as well as the extreme poverty of all soils. The central two-thirds of the state is arid and sparsely inhabited. The only significant economic activity is mining. Annual rainfall averages less than 300 millimetres (8–10 in), most of which occurs in sporadic torrential falls related to cyclone events in summer. An exception to this

3876-611: The generally shallow soils, the only development has taken place along the Ord River . Snow is rare in the state and typically occurs only in the Stirling Range near Albany , as it is the only mountain range far enough south and sufficiently elevated. More rarely, snow can fall on the nearby Porongurup Range . Snow outside these areas is a major event; it usually occurs in hilly areas of southwestern Australia. The most widespread low-level snow occurred on 26 June 1956 when snow

SECTION 50

#1732765238183

3952-466: The greatest number of immigrants to this day. Western Australia—particularly Perth—has the highest proportion of British-born of any state: 10.3% in 2011, compared to a national average of 5.1%. This group is heavily concentrated in certain parts, where they account for a quarter of the population. Perth's metropolitan area (including Mandurah ) had an estimated population of 2,043,138 in June 2017 (79% of

4028-496: The international sandalwood oil market. In recent years, tourism has grown in importance, with significant numbers of visitors to the state coming from the UK and Ireland (28%), other European countries (14%) Singapore (16%), Japan (10%) and Malaysia (8%). Revenue from tourism is a strong economic driver in many of the smaller population centres outside of Perth, especially in coastal locations. Cumulate rocks Cumulate rocks are

4104-902: The magma (possibly to feed volcanic vents or dyke swarms). In such cases, calculating magma chemistries may resolve nothing more than the presence of these two processes having affected the intrusion. Though crystallized at high temperature, cumulate can remelt when later intruded by a sill or dyke of magma. The economic importance of cumulate rocks is best represented by three classes of mineral deposits found in ultramafic to mafic layered intrusions. Silicate minerals are rarely sufficiently valuable to warrant extraction as ore. However, some anorthosite intrusions contain such pure anorthite concentrations that they are mined for feldspar , for use in refractories , glassmaking, semiconductors and other sundry uses ( toothpaste , cosmetics , etc.). Oxide mineral cumulates form in layered intrusions when fractional crystallisation has progressed enough to allow

4180-488: The median individual income was A$ 500 per week in Western Australia (compared to A$ 466 in Australia as a whole). The median family income was A$ 1246 per week (compared to A$ 1171 for Australia). Recent growth has also contributed to significant rises in average property values in 2006, although values plateaued in 2007. Located south of Perth, the heavy industrial area of Kwinana had the nation's largest oil refinery with

4256-415: The melt from which it was formed, but the number of minerals which co-precipitate need to be known, as does the chemistry or mineral species of the precipitated minerals. This is best illustrated by an example; As an example, a magma of basalt composition that is precipitating cumulates of anorthite plagioclase plus enstatite pyroxene is changing composition by the removal of the elements which make up

4332-426: The meridian 129 degrees east of Greenwich, which defines the border with South Australia and the Northern Territory , and bounded by the Indian Ocean to the west and north. The International Hydrographic Organization (IHO) designates the body of water south of the continent as part of the Indian Ocean; in Australia it is officially gazetted as the Southern Ocean . The total length of the state's eastern border

4408-527: The mineral, for example a 99% magnetite cumulate is known as a magnetitite. A specific example is the Skaergaard intrusion in Greenland . At Skaergaard a 2500 m thick layered intrusion shows distinct chemical and mineralogic layering: The Skaergaard is interpreted to have crystallised from a single confined magma chamber. One way to infer the composition of the magma that created the cumulate rocks

4484-513: The north "over 50,000 years ago and possibly as much as 70,000 years ago". Over thousands of years they eventually spread across the whole landmass. These Indigenous Australians were long established throughout Western Australia by the time European explorers began to arrive in the early 17th century. The first Europeans to visit Western Australia were those of the Dutch Dirk Hartog expedition, who on 25 October 1616 landed at what

4560-538: The northern coast, and below that the drier Victoria Plains tropical savanna inland, and the semi-desert Pilbara shrublands , Carnarvon xeric shrublands , and Western Australian mulga shrublands to the southwest. Southwards along the coast are the Southwest Australia savanna and the Swan Coastal Plain around Perth, with the jarrah-karri forest and shrublands on the southwest corner of

4636-677: The oldest known samples of the Earth 's crust : samples of zircon from the Jack Hills portion of the Narryer Gneiss have been radiometrically dated at 4.4 billion years old, although the majority of zircon crystals are about 3.6-3.8 billion years old. The Narryer Gneiss Terrane is adjacent to the northernmost margin of the Yilgarn Craton and is abutted on the north by the Gascoyne Complex metasedimentary and metagranite orogen . The Narryer Gneiss Terrane also includes parts of

SECTION 60

#1732765238183

4712-582: The only mountain-building since then has been of the Stirling Range with the rifting from Antarctica , the land is extremely eroded and ancient, with no part of the state above 1,249 metres (4,098 ft) AHD (at Mount Meharry in the Hamersley Range of the Pilbara region). Most of the state is a low plateau with an average elevation of about 400 metres (1,200 ft), very low relief, and no surface runoff . This descends relatively sharply to

4788-481: The percentage of crystals to their groundmass (Hall, 1996). Cumulate rocks are typically named according to the cumulate minerals in order of abundance, and then cumulate type (adcumulate, mesocumulate, orthocumulate), and then accessory or minor phases. For example: Cumulate terminology is appropriate for use when describing cumulate rocks. In intrusions which have a uniform composition and minimal textural and mineralogical layering or visible crystal accumulations it

4864-443: The percentage of people who identified as having no religious affiliation has increased from 8.7% in 1971 to 42.9% in 2021. A small minority of the population are Muslims (2.5%), Buddhists (2.2%) and Hindus (2.0%). Western Australia's economy is largely driven by extraction and processing of a diverse range of mineral and petroleum commodities. The structure of the economy is closely linked to these natural resources, providing

4940-417: The precipitated minerals. In this example, the precipitation of anorthite (a calcium aluminium feldspar ) removes calcium from the melt, which becomes more depleted in calcium. Enstatite being precipitated from the melt will remove magnesium, so the melt becomes depleted in these elements. This tends to enrich the concentration of other elements - typically sodium, potassium, titanium and iron. The rock that

5016-474: The present state began with the establishment by Lockyer of a convict-supported settlement from New South Wales at King George III Sound . The settlement was formally annexed on 21 January 1827 by Lockyer when he commanded the Union Jack be raised and a feu de joie fired by the troops. The settlement was founded in response to British concerns about the possibility of a French colony being established on

5092-550: The raising of a loan to construct a pipeline to transport 23 megalitres (5 million imperial gallons) of water per day to the burgeoning population on the goldfields. The pipeline, known as the Goldfields Water Supply Scheme , was completed in 1903.  C. Y.  O'Connor , Western Australia's first engineer-in-chief, designed and oversaw the construction of the pipeline. It carries water 530 km (330 mi) from Perth to Kalgoorlie , and

5168-469: The same processes and accumulate due to their high specific gravity , and can form laterally extensive sulfide 'reefs'. The sulfide minerals generally form an interstitial matrix to a silicate cumulate. Sulfide mineral segregations can only be formed when a magma attains sulfur saturation. In mafic and ultramafic rocks they form economic nickel, copper and platinum group (PGE) deposits because these elements are chalcophile and are strongly partitioned into

5244-401: The soils has required heavy application by farmers of fertilisers. These have resulted in damage to invertebrate and bacterial populations. The grazing and use of hoofed mammals and, later, heavy machinery through the years have resulted in compaction of soils and great damage to the fragile soils. Large-scale land clearing for agriculture has damaged habitats for native flora and fauna. As

5320-533: The south-west and southern coastal areas. As of 2021, the state has 2.91 million inhabitants—11 percent of the national total. Over 90 percent of the state's population live in the south-west corner and around 80 percent live in the state capital Perth , leaving the remainder of the state sparsely populated. The Trans-Australian Railway and the Eyre Highway traverse the Nullarbor Plain in

5396-555: The state and national economy. In the period 2010–2019 wheat production in WA has averaged nearly 10 million tonnes (22 billion pounds), valued at $ 2.816   billion in 2019, accounting for half the nation's total and providing $ 2–3   billion in export income. Other significant farm output includes wool, beef, lamb, barley, canola, lupins, oats and pulses. There is a high level of overseas demand for live animals from WA, driven mainly by southeast Asia's feedlots and Middle Eastern countries, where Islamic dietary laws and

5472-431: The state's south-east, providing the principal connection between Western Australia and the population centres in the eastern states . Western Australia's Indigenous peoples have been present for tens of thousands of years. Dutch explorers visited Western Australia from the 17th century, with Dirk Hartog 's 1616 expedition the first Europeans to make landfall. The British claimed Western Australia in 1827 and established

5548-451: The state). Other significant population centres include Bunbury (73,989), Geraldton (37,961), Kalgoorlie-Boulder (30,420), Albany (33,998), Karratha (16,446), Broome (14,501) and Port Hedland (14,285). At the 2016 census, the most commonly nominated ancestries were: 3.1% of the population, or 75,978 people, identified as Indigenous Australians ( Aboriginal Australians and Torres Strait Islanders ) in 2016. At

5624-550: The time transportation ceased in 1868, convicts outnumbered free settlers 9,700 to 7,300. In the 1890s, interstate immigration, resulting from a mining boom in the Goldfields region , resulted in a sharp population increase. Western Australia did not receive significant flows of immigrants from Britain, Ireland or elsewhere in the British Empire until the early 20th century. At that time, its local projects—such as

5700-542: The typical product of precipitation of solid crystals from a fractionating magma chamber. These accumulations typically occur on the floor of the magma chamber, although they are possible on the roofs if anorthite plagioclase is able to float free of a denser mafic melt. Cumulates are typically found in ultramafic intrusions , in the base of large ultramafic lava tubes in komatiite and magnesium rich basalt flows and also in some granitic intrusions. Cumulates are named according to their dominant mineralogy and

5776-653: Was reported in the Perth Hills , as far north as Wongan Hills and as far east as Salmon Gums . However, even in the Stirling Range, snowfalls rarely exceed 5 cm (2 in) and rarely settle for more than one day. The highest observed temperature of 50.7 °C (123.3 °F) was recorded in Onslow on 13 January 2022. The lowest temperature recorded was −7.2 °C (19.0 °F) at Eyre Bird Observatory on 17 August 2008. The south geomagnetic pole

#182817