Hadean zircon

Last updated

Hadean zircon is the oldest-surviving crustal material from the Earth's earliest geological time period, the Hadean eon, about 4 billion years ago. Zircon is a mineral that is commonly used for radiometric dating because it is highly resistant to chemical changes and appears in the form of small crystals or grains in most igneous and metamorphic host rocks. [1]

Contents

Aerial photo of the Jack Hills, Australia Jack Hills, Western Australia (Landsat 5 TM, 2009-07-14, detail).jpg
Aerial photo of the Jack Hills, Australia

Hadean zircon has very low abundance around the globe because of recycling of material by plate tectonics. When the rock at the surface is buried deep in the Earth it is heated and can recrystallise or melt. [1] In the Jack Hills, Australia, scientists obtained a relatively comprehensive record of Hadean zircon crystals in contrast to other locations. The Jack Hills zircons are found in metamorphosed sediments that were initially deposited around 3 billion years ago, [1] or during the Archean Eon. However, the zircon crystals there are older than the rocks that contain them. Many investigations have been carried out to find the absolute age and properties of zircon, for example the isotope ratios, mineral inclusions, and geochemistry of zircon. The characteristics of Hadean zircons show early Earth history and the mechanism of Earth's processes in the past. [1] Based on the properties of these zircon crystals, many different geological models were proposed.

Background

Importance

Deeper understanding of Earth history

The geological history of the Hadean eon of early earth is poorly known due to the lack of rock record older than 4.02 Ga (giga-annum or billion years). [2] [3] [4] Most scientists accept that the plate recycling mechanism has melted almost all pieces of Earth's crust. [2] However, some tiny parts of the crust have not been melted, as some rare Hadean zircon grains included in much younger host rock were discovered. [2] The examination of Hadean detrital or inherited grains of zircon can give evidence of geophysical conditions of the early earth. [4]

Scientific contribution

Since there is no strong evidence depicting the early Earth's true environment, many models are generated to explain early Earth history. [1] The high value of Hadean heat production and impact flux proved that continental crust did not exist, which is very different from the modern process. In the absence of large amount of undistributed data and within the constraints of analytical methods, calculation on geophysics and planetary science has been rapidly developed to explore this new area of knowledge. [1]

Abundance

Less than 1% of zircons detected around the world are over four billion years old. [1] The probability of discovering so much as a single zircon over four billion years in age is very low. [1] The abundance of over four billion-year-old zircon in the Jack Hills is anomalously high for most Archean quartzites and thus abundances probabilities of other spots are extremely low (0.2–0.02%). [5] [ failed verification ]

By adopting uranium-lead dating (U-Pb) together with other analytical methods, more geochemical information can be obtained. Only 3% out of over 200,000 detrital zircon grains dated by U-Pb analysis are over four billion years old. [6] [7]

A uranium to ytterbium concentration ratio versus yttrium concentration plot (U/Yb vs Y) shows different trace elements signatures of zircon sources. Stars are the data for Kimberlite zircon, triangles are Hadean Jack Hills zircon and circles are ocean crust zircon. Zircon type.png
A uranium to ytterbium concentration ratio versus yttrium concentration plot (U/Yb vs Y) shows different trace elements signatures of zircon sources. Stars are the data for Kimberlite zircon, triangles are Hadean Jack Hills zircon and circles are ocean crust zircon.

Types

Due to different content of uranium and trace element concentration, four clusters of zircons are identified as below [1]

Low crystallisation temperatures and trace element characteristics are the two major characteristics that differentiate mantle derived zircon or oceanic crust-derived zircon. [8] [9] [10] Lunar and meteoritic zircons are unique because of their REE signature for example, lack of a cerium anomaly. [11] The crystallization temperature ranges from 900 to 1100 °C. In contrast, terrestrial Hadean zircons are restricted to 600 to 780 °C. [12] Hadean Jack Hills zircon has a wide range of oxygen fraction comparing to meteoritic zircons. [12] No extraterrestrial zircons were found in any terrestrial locality. The textural characteristics like the growth zoning and inclusion mineralogy shows that Hadean zircon from the Jack Hills all come from igneous sources. [13] [14]

Properties

Histograms for concordant Jack Hills zircons. This is a histogram of rapid initial survey of individual Pb/ Pb ages undertaken to identify the >4.2Ga population. There are 3 dominant peaks and 2 minor peaks. Zircon Age distribution U-Pb.png
Histograms for concordant Jack Hills zircons. This is a histogram of rapid initial survey of individual Pb/ Pb ages undertaken to identify the >4.2Ga population. There are 3 dominant peaks and 2 minor peaks.

The unspecified samples used for analyses below were Jack Hills zircon in Australia because of the high abundances and data available.

Age distribution

U-Pb dating in the U-Pb zircon system has long been viewed as the crustal geochronometer because zircon is chemically resistant and enriched in U and Th compared to the daughter product Pb. [16] Trace element and isotopic composition of zircon is important to determine the crystallisation environment. [16]

Results from detrital zircons from the Erawondoo Hill discovery site conglomerate [17] [18] generally show the zircons to have a bimodal age distribution with major peaks at c. 3.4 and 4.1 Ga.

However, zircon is sensitive to radiation damage and can degrade into amorphous material. [19] The Hadean zircon with original uranium concentrations greater than 600 ppm is challenged by the effect of post-crystallization alteration.

Isotope geochemistry

Stable isotope data, indicating that the original host rocks to the zircon related to a significant amount of material formed on or near the Earth's surface and subsequently transferred to a middle- to lower-crustal level where they melted to generate the host magmas from which zircon crystallised. [6] [13]

Data typeObservationInterpretationLimitation
Oxygen isotope ratios Granitoids with lower ઠ18O valuesThere were hydrothermal interactions with meteoric water instead of weathering. [20] [21] There is a lack of comprehensive record of the analysed areas within the grains, which leads to difficulty in relating ages of specifically dated parts of the zircon grains to their oxygen and hafnium isotope systematics and trace element concentrations. [22]
Ratios of oxygen isotopes have been measured in Hadean zircons. High value of 18ઠSMOW observed in Hadean Jack Hills zircons led to two different ideas about the source of Hadean zircon. [22] [6] 18O-enriched clay minerals were found in the host rock of zircon grains.Water was present on the Earth's surface around 4.3 Ga. [6]
Hadean Jack Hills zircons contain more 18O-enrichments than the mantle zircon about 5.3%. [23] I-type granitoids protoliths give relatively low ઠ18O values while those derived by S type metasedimentary rocks have higher ઠ18O values.The presence in the protolith of recycled crustal material that had interacted with liquid water under surface, or near surface, condition. [23]
Lutetium-hafnium The ratio of isotopes of hafnium 176Hf/177Hf data in crustal rocks being consistent with the formation of crust since 4.5 Ga. [24] [25] Lu-Hf systematics potentially indicating existence of an early formed reservoir, similar to continental crust in its degree of Lu depletion relative to Hf. [24] [25] Most of the data matches the formation of crust at 4.5 Ga while some zircon data is unreasonable requiring the removal of protolith from chrondritic uniform reservoir (CHUR). Since these extra findings, studies cannot conform the positive value of EHf(T) due to the complication of Hf isotope analysis and lack of U-Pb date being simultaneously available. [24]
Cluster of results along a line corresponding to a Lu/Hf ~0.01, low reservoir at ~4Ga [26] The data is consistent with either early extraction of very felsic crust or by remelting of a primordial basaltic reservoir, but in either case extrapolation of this trend yields a present-day εHf(T) of approximately −100 [25] [26] A recycling event c. 3.9–3.7 Ga which resembles the Hf isotope evolution of modern subduction-related orogens and so may have additional tectonic significance. [26]
Plutonium-xenonSome Hadean zircon grains originally contained plutonium, an element that has since disappeared from the natural environment. In the meteorite record, the abundance ratio of initial plutonium to uranium (Pu/U) was about 0.007 and 244Pu was present in the early Solar System. [27] The result of the ratio can be interpreted as xenon loss during later metamorphism. Uranium became oxidised to soluble uranyl ion (UO22+) while the solubility of plutonium compounds is low, variations in Pu/U are regarded as an effective indicator of aqueous alteration in Jack Hills protoliths. [28] Only Nd/U has correlations expected from aqueous processes excluding analysis of Xe isotopic ratios, U-Pb age, trace element contents, and δ18O [27] [28]
The initial Pu/U ratios of Jack Hills zircon ranges from c. 0.007 to zero. [28] Due to Xe loss during later metamorphism. Variation in Pu/U has been suggested as a potential indicator of aqueous alteration in the Jack Hills zircon protoliths [28]
High-Nd/U zircons display only low Pu/U, while Nd/U zircons show more heterogeneous Pu/U [28] High-Nd/U group appears less magmatically evolved than other Hadean zircons, has REE patterns suggestive of some degree of alteration, either by hydrothermal fluid interaction or phosphate replacement, and consists of solely low-Pu/U zircons with a range of Hadean to Proterozoic U-Xe ages [27] [28]
Lithium Lithium isotopes significantly vary in Hadean zircon. The 7Li isotope result of Hadean Jack Hills zircons gave highly negative values. [29] The environment of forming zircon as highly weathered. [29] A high lithium diffusion rate in zircon at low temperature [30] and exchange with hydrogen during metamorphism are two examples of subsequent variations to lithium that may limit the usefulness of the measurements [30]
Li is homogeneously distributed within single growth zones of the zircons. Jack Hills zircons are zoned in both 7Li and Li concentration. [31] These values correlate with igneous growth zoning. [32] [31]

Mineral inclusions

Greenish brown biotite with opaque magnetite inclusions and yellow-violet muscovite (cross polarized microscopic view) Biotite and muscovite.jpg
Greenish brown biotite with opaque magnetite inclusions and yellow-violet muscovite (cross polarized microscopic view)

The development of textural criteria for identifying primary inclusions [33] opens up possibilities for recognising zircons' changing provenance with time and investigating their post-depositional alteration history. There are two common inclusion assemblages that are consistent with their forming in "I-type" (hornblende, quartz, biotite, plagioclase, apatite, ilmenite) and "S-type" (quartz, K-feldspar, muscovite, monazite) granitoids. [33] Dominated by quartz with less abundant K-feldspar, plagioclase, muscovite, biotite, and phosphates, that are interpreted to have formed under relatively low geothermal gradient similar to that pertaining to modern subduction zones. [14] [33]

Data typeObservationInterpretation
Muscovite Quartz and muscovite are the principal inclusion phases, potentially pointing to an aluminous granitic source. [14] [34] Hopkins (2010) used a thermodynamic solution model for celadonite substitution in muscovite [35] to estimate pressures for muscovite inclusions in magmatic zircons. The result revealed that the pressure conditions for over 1700 inclusion samples is greater than 5  kbar, coupled with a relatively low host zircons crystallization temperature. [35] Muscovite inclusion coupled with a thermodynamic model implied that the Earth surface had a remarkably low heat flow. This result led scientists to suggest formation in an underthrust or subduction-like environment as found on the modern Earth [14] [34]
Iron oxides Cerium anomaly of a zircon (Ce/Ce*) is a quantitative investigation for host magma fO2. [36] Hadean Jack Hills zircons show a range in fO2 with an average near the fayalite-magnetite-quartz (FMQ) buffer. [37] The Hadean geological setting is similar to the modern upper mantle [36] [37]
Biotite Composition of biotite differ among granitoids. FeO, MgO and Al2O3 content isolate calc-alkaline, peraluminous and alkaline granitoids. [38] [ full citation needed ]The nature of Hadean melt compositions can be known. [38]
Sulfide and carbonaceous phases have been revealed in Hadean zircon though the number of cases is small. [38] The rare phases have deleted the volatile contents in Hadean magmas and source materials. [38]
Graphite By knowing the occurrence of carbon, existence of life can be revealed in the aspect of timing, conditions and mechanisms. [39] [40] Isotopic result identified the zircon was 3.8 to 3.5 billion years age and metabolism has occurred within the host microbiota. [39] [40]

Zircon geochemistry

By analysing the content of zircon, some zircon show the presence of titanium, rare earth minerals, lithium, aluminium and carbon. Certain ratio and normal distribution give evidence of zircon's origin and the source of magma.

Data typeObservationInterpretationLimitation
Titanium The content of Ti-in-zircon serves as a crystallization thermometer given knowledge of the melt aSiO2 and aTiO2. [41] [42] The Ti measurements were applied to grains ranging from 3.91 to 4.35 Ga and the majority of the data plots a normal distribution graph. [41] Crystallisation of Ti-in-zircon grains are from evolved melts [41] It yielded an extremely high temperature 680±25 °C. Since the crystallisation of rutile is unknown, researchers can only estimate the temperature by calculation. [43]
Rare-earth mineral Cerium anomaly of a zircon (Ce/Ce*) is a quantitative investigation for host magma fO2. [42] The result showed low value of Ce/Ce* ratio.Diversity of source materials [42] REE signatures in some zircon grains that have been interpreted to indicate crystallisation of these grains from evolved melts. [41] [42] [43]
In EDS analysis, magnetite was dominant in the inclusion instead of ilmenite in granitoids. [44] Hydrothermal alternation of zircon is often determined by high, flat light rare-earth mineral (LREE) pattern. [44]
Lithium Li zoning in zircon serve as a peak temperature indicator while examining retention of primary remanent magnetic signals. [32] Jack Hills zircon containing c. 5up-wide Li concentration band which required below 500 °C peak heating temperature of zircon.The grains can be applied to study primary magnetism because it did not exceed the Curie temperature which is 585 °C for magnetite. [32] The metaconglomerates at Erawondoo Hill did not experience temperature greater than 500 °C. [31] The result showed that there is variation of data and thermal history in different occurrences. [31]
Aluminium Peraluminous granitoids contain around 10 ppm aluminium in Jack Hills zircon [32] while the I-type and A-type zircon obtained average 1.3 ppm. The molar value of Al2O3/(CaO+Na2O+K2O) greater than 1. [45] The origin is from recycled pelitic material. [45] Small amount of sample zircon contains high Al contents suggests that metaluminous crustal rocks is more common than peraluminous rocks in the Hadean. However, the c. 20% overlap of low Al (i.e., < 5 ppm) in S-type zircons somewhat obscures this inference. [46]
Some of the grains show high aluminium content [45] Metaluminous crustal rocks may be more common than peraluminous rocks in the Hadean. [45]
Carbon Scientists measured concentration of carbon in the form of graphite in zircon by using secondary ion mass spectrometer (SIMS). Detecting Hadean crustal carbon could ensure that there was a transfer of carbon from mantle reservoirs [47] Allow the selection among models of the early earth. [48] Quite a few early earth models contain this property which cannot confirm which model is correct [47] [48]

Analytic method

Ion microprobe analysis Principe FIB-en.svg
Ion microprobe analysis

Ion microprobe analysis

Ion microprobe (or secondary ion mass spectrometry, SIMS) and uranium-thorium-lead geochronology are two common methods to measure isotope in specific time interval. [49] [50]

Highly precise in situ SIMS measurements of oxygen isotopes [51] and OH/O ratios, laser-ablation inductively-coupled mass spectrometry (LA-ICP-MS) determination of hafnium isotopes, [52] [53] and atom-probe tomography. [54] LA-ICP-MS is the most common method to date using isotopes but it lacks capacity to measure 204Pb. Therefore, there is a possibility that the occurrences of single zircons over 4 billion years old could be due to inclusion of non-radiogenic Pb.

Electron probe microanalyser EPMA.jpg
Electron probe microanalyser

U-Pb dating, delta 18O and Ti measurements can be tested by CAMECA ims 1270 ion microprobe. [51] Epoxy are applied on the sample. A flat surface of sample is needed to conduct an analysis. [55] U-Pb dating and T measurement uses a primary O− beam with low intensity (10-15 nA). U-Pb age standard AS3 was used for dating studies. The concentration of Ti can be determined based on analysis of Jack Hills zircon [55] and NIST610 glass.

Electron microprobe analysis

For inclusions investigation, JEOL 8600 electron microprobe analyzer (EPMA) were used to chemically analyze zircon. [1] It is used to analyze the chemical composition of material. Electron beams are emitted to the mineral's surface and blow off ions and estimate the abundance of the elements within a very small sized sample. Many isotopes can be measured at once in this analysis for example Ti and Li. [32]

Occurrence

The red dots represent the location of Hadean zircon on the world map Zircon world map.pdf
The red dots represent the location of Hadean zircon on the world map
OccurrencesAnalytic method and resultInterpretation

Australia

Mt. Narryer [56] [57] Ion microprobe dating of 80 detrital zircons from quartzites have disclosed that 2% to 12% grains >4.0Ga, with younger zircons ranging to ca.3 Ga. In the LA-ICP-MS study, Mt. Narryer zircons has higher U contents and lowest Ce/Ce* in contrast to Jack Hills zirconsDiversity of source rock. Magmatic origins.
Churla Wells [58] The grains are 4.14 to 4.18Ga by using 207Pb/206Pb dating. Core region has a much lower Hf, REE, Uand Th than other outer region. While U content in core is around 666ppm, Th/U is 0.6.Granitic magma origin
Maynard Hills [59] Dating of greenstone belt revealed that the 207Pb/206Pb age is 4.35Ga./
Mt Alfred [60] The concordant zircon has the age 4.17Ga. No geochemistry data has been collected/

North America

Northwest Territory, Canada [61] [62] [63] The protolith crystallisation age is 3.96Ga analysed by U-Pb dating. Applying LA-ICP-MS, 4.20+0.06Ga zircon was being dated. The unaltered zircon under the above method obtained LREE pattern.Magmatic origin. Derivation from a felsic melt by a process other than differentiation of a mafic magma
Greenland [64] [65] The crystallisation age is determined as 3.83±0.01Ga by ion microprobe dating. 4.08±0.02Ga was identified in U-Pb survey/

Asia

Tibet [66] In ion microprobe method, detrital grain's Th/U ratios is greater than 0.7Magmatic origin
North Qinling [67] The LA-ICP-MS age of xenocrystic zircon in North Qinling Orogenic Belt is 4.08Ga. Hf isotope also support the age data of LA-ICP-MS test/
North China Craton [68] The zircon is 4.17±0.05Ga determined by LA-ICP-MS U-Pb dating method. Th/U ratio is 0.46Magmatic origin
South China [69] Conducting ion microprobe U-Pb dating, 207Pb/206Pb age is 4.13±0.01 Ga with 5.9±0.1% 18O isotope data. Positive Ce anomalyearly earth is a highly oxidizing environment and a high Ti-in-zircons crystallization temperature of 910'C.

South America

Southern Guyana [70] 4.22Ga by LA-ICP-MS U-Pb dating method. No other geochemical analysis has been conducted/
Eastern Brazil [71] The age of the rock is 4.22Ga and Th/U ratios of 0.8 and high U contents (up to 1400ppm)Felsic magmatic origin

Proposed mechanisms for forming Hadean Jack Hills zircons

Modern plate tectonic theory Cross-section of a subduction zone and back-arc basin.jpg
Modern plate tectonic theory

Plate tectonic theory is widely accepted for the generation of crust. With the Hadean rock record, most of the scientists concluded that the hypothesis of a hellish early Earth devoid of ocean is incorrect. [1] Scientists have constructed different models to explain the thermal history in the early earth, such as the continental growth model, [72] Icelandic rhyolites, [73] intermediate igneous rocks, mafic igneous rocks, sagduction, [74] impact melt, [75] heat-pipe tectonics, [76] terrestrial KREEP [77] and multi-stage scenarios.

The most famous one is continental growth model which is similar to the modern tectonic dynamics. [1]

Relatively low crystallisation temperature and some are enriched in heavy oxygen, contain inclusion similar to modern crustal processes and show evidence of silicate differentiation at ~4.5 Ga. [1] Early terrestrial hydrosphere, early felsic crust in which granitoids were produced and later weathered under high water activity conditions and even the possible existence of plate boundary interactions. [1] [78]

Related Research Articles

The Precambrian is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic Eon, which is named after Cambria, the Latinized name for Wales, where rocks from this age were first studied. The Precambrian accounts for 88% of the Earth's geologic time.

<span class="mw-page-title-main">Zircon</span> Zirconium silicate mineral

Zircon is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is ZrSiO4. An empirical formula showing some of the range of substitution in zircon is (Zr1–y, REEy)(SiO4)1–x(OH)4x–y. Zircon precipitates from silicate melts and has relatively high concentrations of high field strength incompatible elements. For example, hafnium is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal system. The natural color of zircon varies between colorless, yellow-golden, red, brown, blue, and green.

The Hadean is the first and oldest of the four known geologic eons of Earth's history, starting with the planet's formation about 4.6 billion years ago, and ended 4.031 billion years ago. The interplanetary collision that created the Moon occurred early in this eon. The Hadean eon was succeeded by the Archean eon, with the Late Heavy Bombardment hypothesized to have occurred at the Hadean-Archean boundary.

<span class="mw-page-title-main">Sensitive high-resolution ion microprobe</span>

The sensitive high-resolution ion microprobe is a large-diameter, double-focusing secondary ion mass spectrometer (SIMS) sector instrument that was produced by Australian Scientific Instruments in Canberra, Australia and now has been taken over by Chinese company Dunyi Technology Development Co. (DTDC) in Beijing. Similar to the IMS 1270-1280-1300 large-geometry ion microprobes produced by CAMECA, Gennevilliers, France and like other SIMS instruments, the SHRIMP microprobe bombards a sample under vacuum with a beam of primary ions that sputters secondary ions that are focused, filtered, and measured according to their energy and mass.

<span class="mw-page-title-main">Acasta Gneiss</span> Metamorphic rock unit in Canada

The Acasta Gneiss Complex, also called the Acasta Gneiss, is a body of felsic to ultramafic Archean basement rocks, gneisses, that form the northwestern edge of the Slave Craton in the Northwest Territories, Canada, about 300 km (190 mi) north of Yellowknife, Canada. This geologic complex consists largely of tonalitic and granodioritic gneisses and lesser amounts of mafic and ultramafic gneisses. It underlies and is largely concealed by thin, patchy cover of Quaternary glacial sediments over an area of about 13,000 km2 (5,000 sq mi). The Acasta Gneiss Complex contains fragments of the oldest known crust and record of more than a billion years of magmatism and metamorphism. The Acasta Gneiss Complex is exposed in a set of anticlinoriums within the foreland fold and thrust belt of the Paleoproterozoic Wopmay Orogen.

<span class="mw-page-title-main">Jack Hills</span> Range of hills in Western Australia

The Jack Hills are a range of hills in Mid West Western Australia. They are best known as the source of the oldest material of terrestrial origin found to date: Hadean zircons that formed around 4.404 billion years ago. These zircons have enabled deeper research into the conditions on Earth in the Hadean eon. Potentially biogenic carbon isotope ratios have been identified for graphite embedded within a 4.1 billion-year-old zircon from the site.

<span class="mw-page-title-main">Metaconglomerate</span>

Metaconglomerate is a rock type which originated from conglomerate after undergoing metamorphism. Conglomerate is easily identifiable by the pebbles or larger clasts in a matrix of sand, silt, or clay. Metaconglomerate looks similar to conglomerate, although sometimes the clasts are deformed. The cement matrix of conglomerate is not as durable as the grains, and hence when broken, conglomerate breaks around the grains. Metaconglomerate, however, breaks through the grains, as the cement has recrystallized and may be as durable as the clasts.

<span class="mw-page-title-main">Oldest dated rocks</span> Includes rocks over 4 billion years old from the Hadean Eon

The oldest dated rocks formed on Earth, as an aggregate of minerals that have not been subsequently broken down by erosion or melted, are more than 4 billion years old, formed during the Hadean Eon of Earth's geological history, and mark the start of the Archean Eon, which is defined to start with the formation of the oldest intact rocks on Earth.

<span class="mw-page-title-main">Isua Greenstone Belt</span> Archean greenstone belt in southwestern Greenland

The Isua Greenstone Belt is an Archean greenstone belt in southwestern Greenland, aged between 3.7 and 3.8 billion years. The belt contains variably metamorphosed mafic volcanic and sedimentary rocks, and is the largest exposure of Eoarchaean supracrustal rocks on Earth. Due to its age and low metamorphic grade relative to many Eoarchaean rocks, the Isua Greenstone Belt has become a focus for investigations on the emergence of life and the style of tectonics that operated on the early Earth.

<span class="mw-page-title-main">Grouse Creek block</span> Accreted terrane west of the Wyoming craton

The Grouse Creek block is a Precambrian basement province of 2.45 to 2.70 billion year old orthogneisses. The Grouse Creek block is one of several Proterozoic and Archean accreted terranes that lie to the north and west of the Wyoming craton, including the Farmington Canyon Complex, the Selway terrane, the Medicine Hat block and the Priest River complex. Together, these terranes comprise part of the basement rock of the North American continent and have been critical to studies of crustal accretion in the Precambrian. Ongoing study of the Grouse Creek block will contribute to understanding the paleogeography of the Wyoming craton prior to its incorporation into the supercontinent Laurentia approximately 1.86 billion years ago. The name was proposed by David Foster and others.

The Chaotian is a proposed time division of the geologic time scale. First proposed in 2010 as an eon, it is named after Chaos, the primeval void in Greek mythology. This proposal defines the Chaotian eon as a Solar System-wide time between the initiation of planetary formation and the hypothesised collision of the trojan dwarf planet Theia with the proto-Earth.

<span class="mw-page-title-main">Provenance (geology)</span>

Provenance in geology, is the reconstruction of the origin of sediments. The Earth is a dynamic planet, and all rocks are subject to transition between the three main rock types: sedimentary, metamorphic, and igneous rocks. Rocks exposed to the surface are eventually broken down into sediments. Sediments are expected to be able to provide evidence of the erosional history of their parent source rocks. The purpose of provenance study is to restore the tectonic, paleo-geographic and paleo-climatic history.

<span class="mw-page-title-main">Titanium in zircon geothermometry</span>

Titanium in zircon geothermometry is a form of a geothermometry technique by which the crystallization temperature of a zircon crystal can be estimated by the amount of titanium atoms which can only be found in the crystal lattice. In zircon crystals, titanium is commonly incorporated, replacing similarly charged zirconium and silicon atoms. This process is relatively unaffected by pressure and highly temperature dependent, with the amount of titanium incorporated rising exponentially with temperature, making this an accurate geothermometry method. This measurement of titanium in zircons can be used to estimate the cooling temperatures of the crystal and infer conditions during which it crystallized. Compositional changes in the crystals growth rings can be used to estimate the thermodynamic history of the entire crystal. This method is useful as it can be combined with radiometric dating techniques that are commonly used with zircon crystals, to correlate quantitative temperature measurements with specific absolute ages. This technique can be used to estimate early Earth conditions, determine metamorphic facies, or to determine the source of detrital zircons, among other uses.

<span class="mw-page-title-main">Detrital zircon geochronology</span> Science of analyzing the age of zircons

Detrital zircon geochronology is the science of analyzing the age of zircons deposited within a specific sedimentary unit by examining their inherent radioisotopes, most commonly the uranium–lead ratio. Zircon is a common accessory or trace mineral constituent of most granite and felsic igneous rocks. Due to its hardness, durability and chemical inertness, zircon persists in sedimentary deposits and is a common constituent of most sands. Zircons contain trace amounts of uranium and thorium and can be dated using several modern analytical techniques.

<span class="mw-page-title-main">Monazite geochronology</span> Dating technique to study geological history using nuclear decay of the mineral monazite

Monazite geochronology is a dating technique to study geological history using the mineral monazite. It is a powerful tool in studying the complex history of metamorphic rocks particularly, as well as igneous, sedimentary and hydrothermal rocks. The dating uses the radioactive processes in monazite as a clock.

<span class="mw-page-title-main">Eoarchean geology</span> Study of the oldest crustal fragments on Earth

Eoarchean geology is the study of the oldest preserved crustal fragments of Earth during the Eoarchean era from 4.031 to 3.6 billion years ago. Major well-preserved rock units dated to this era are known from three localities, the Isua Greenstone Belt in Southwest Greenland, the Acasta Gneiss in the Slave Craton in Canada, and the Nuvvuagittuq Greenstone Belt in the eastern coast of Hudson Bay in Quebec. From the dating of rocks in these three regions, scientists suggest that the beginning of plate tectonics could have started as far back as early as the Eoarchean.

<span class="mw-page-title-main">Lutetium–hafnium dating</span> Gochronological dating method utilizing the radioactive decay system of lutetium–176

Lutetium–hafnium dating is a geochronological dating method utilizing the radioactive decay system of lutetium–176 to hafnium–176. With a commonly accepted half-life of 37.1 billion years, the long-living Lu–Hf decay pair survives through geological time scales, thus is useful in geological studies. Due to chemical properties of the two elements, namely their valences and ionic radii, Lu is usually found in trace amount in rare-earth element loving minerals, such as garnet and phosphates, while Hf is usually found in trace amount in zirconium-rich minerals, such as zircon, baddeleyite and zirkelite.

<span class="mw-page-title-main">Eastern Block of the North China Craton</span>

The Eastern Block of the North China Craton is one of the Earth's oldest pieces of continent. It is separated from the Western Block by the Trans-North China Orogen. It is situated in northeastern China and North Korea. The Block contains rock exposures older than 2.5 billion years. It serves as an ideal place to study how the crust was formed in the past and the related tectonic settings.

<span class="mw-page-title-main">Dharwar Craton</span> Part of the Indian Shield in south India

The Dharwar Craton is an Archean continental crust craton formed between 3.6-2.5 billion years ago (Ga), which is located in southern India and considered the oldest part of the Indian peninsula.

John Williams Valley is an American geochemist and petrologist. He is an expert on stable isotope geochemistry, especially as applied to understanding the evolution of the Earth's crust.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Harrison, T. (2009). The Hadean Crust: Evidence from >4 Ga Zircons. Annual Review of Earth and Planetary Sciences,37, 479-505.
  2. 1 2 3 Bowring;Williams, Samuel A;Ian S. (1999). "Priscoan (4.00±4.03 Ga) orthogneisses from northwestern Canada". Contrib Mineral Petrol. 134 (1): 3–16. Bibcode:1999CoMP..134....3B. doi:10.1007/s004100050465. S2CID   128376754.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ↑ Willbold, Mojzsis, Chen, & Elliott. (2015). Tungsten isotope composition of the Acasta Gneiss Complex. Earth and Planetary Science Letters,419, 168-177.
  4. 1 2 Roth, Bourdon, Mojzsis, Touboul, Sprung, Guitreau, & Blichert-Toft. (2013). Inherited 142Nd anomalies in Eoarchean protoliths. Earth and Planetary Science Letters,361, 50-57.
  5. ↑ Harrison, T., Blichert-Toft, J., Mueller, W., Albarede, F., Holden, P., & Mojzsis, S. (2005). "Heterogeneous Hadean hafnium; evidence of continental crust at 4.4 to 4.5 Ga". Science,310(5756), 1947–1950.
  6. 1 2 3 4 Peck, Valley, Wilde, & Graham. (2001). "Oxygen isotope ratios and rare earth elements in 3.3 to 4.4 Ga zircons: Ion microprobe evidence for high δ18O continental crust and oceans in the Early Archean". Geochimica Et Cosmochimica Acta,65(22), 4215-4229.
  7. ↑ Hiess, Nutman, Bennett, & Holden. (2006). "Ti zircon thermometry applied to metamorphic and igneous systems". Geochimica Et Cosmochimica Acta,70(18), A250.
  8. ↑ Grimes, C., John, B., Kelemen, P., Mazdab, F., Wooden, J., Cheadle, M., . . . Schwartz, J. (2007). Trace element chemistry of zircons from oceanic crust; a method for distinguishing detrital zircon provenance. Geology (Boulder),35(7), 643-646.
  9. ↑ Lassiter, Byerly, Snow, & Hellebrand. (2014). Constraints from Os-isotope variations on the origin of Lena Trough abyssal peridotites and implications for the composition and evolution of the depleted upper mantle. Earth and Planetary Science Letters,403, 178-187.
  10. ↑ Coogan, L., & Hinton, R. (2006). Do the trace element compositions of detrital zircons require Hadean continental crust? Geology (Boulder),34(8), 633-636.
  11. ↑ Martin, Duchêne, Deloule, & Vanderhaeghe. (2006). Oxygen isotopes, REE and U–Pb behaviour during metamorphic zircon formation. Geochimica Et Cosmochimica Acta,70(18), A394.
  12. 1 2 Watson, E., & Harrison, T. (2005). Zircon thermometer reveals minimum melting conditions on earliest Earth. Science,308(5723), 841-844.
  13. 1 2 Cavosie AJ, Wilde SA, Liu D, Weiblen PW, Valley JW (2004) Internal zoning and U–Th–Pb chemistry of Jack Hills detrital zircons: a mineral record of early Archean to Mesoproterozoic (4348–1576 Ma) magmatism. Precambrian Res 135:251–279
  14. 1 2 3 4 Hopkins M, Harrison TM, Manning CE (2008) Low heat flow inferred from > 4 Gyr zircons suggests Hadean plate boundary interactions. Nature 456:493–496
  15. ↑ Holden P, Lanc P, Ireland TR, Harrison TM, Foster JJ, Bruce ZP (2009). "Mass-spectrometric mining of Hadean zircons by automated SHRIMP multi-collector and single-collector U/Pb zircon age dating: The first 100 000 grains". International Journal of Mass Spectrometry 286:53–63
  16. 1 2 Meinhold, G., Morton, A., Fanning, C., & Whitham, A. (2011). "U–Pb SHRIMP ages of detrital granulite-facies rutiles: Further constraints on provenance of Jurassic sandstones on the Norwegian margin". Geological Magazine,148(3), 473–480.
  17. ↑ Crowley, Bowring, Shen, Wang, Cao, & Jin. (2006). "U–Pb zircon geochronology of the end-Permian mass extinction". Geochimica Et Cosmochimica Acta,70(18), A119.
  18. ↑ Iizuka, Tsuyoshi; Yamaguchi, Akira; Haba, Makiko K.; Amelin, Yuri; Holden, Peter; Zink, Sonja; Huyskens, Magdalena H.; Ireland, Trevor R. (January 2015). "Timing of global crustal metamorphism on Vesta as revealed by high-precision U–Pb dating and trace element chemistry of eucrite zircon". Earth and Planetary Science Letters. 409: 182–192. Bibcode:2015E&PSL.409..182I. doi:10.1016/j.epsl.2014.10.055. hdl: 1885/22438 . S2CID   140575706.
  19. ↑ Bengtson, Ewing, & Becker. (2012). "Corrigendum to 'He diffusion and closure temperatures in apatite and zircon: A density functional theory investigation' [Geochim. Cosmochim. Acta 86 (2012) 228–238]". Geochimica Et Cosmochimica Acta,98, 202.
  20. ↑ Valley JW, Chiarenzelli JR, McLelland JM (1994). "Oxygen isotope geochemistry of zircon". Earth and Planetary Science Letters 126:187–206
  21. ↑ Trail D, Bindeman IN, Watson EB, Schmitt AK (2009). "Experimental calibration of oxygen isotope fractionation between quartz and zircon". Geochimica ey Cosmochimica Acta 73:7110–7126
  22. 1 2 Abbott, S., Harrison, T., Schmitt, A., & Mojzsis, S. (2012). "A search for thermal excursions from ancient extraterrestrial impacts using Hadean zircon Ti-U-Th-Pb depth profiles". Proceedings of the National Academy of Sciences of the United States of America,109(34), 13486–13492.
  23. 1 2 Valley JW, Kinny PD, Schulze DJ, Spicuzza MJ (1998). "Zircon megacrysts from kimberlite: oxygen isotope variability among mantle melts". Contributions to Mineralogy and Petrology 133:1–11
  24. 1 2 3 Kinny PD, Compston W, Williams IS (1991). "A reconnaissance ion-probe study of hafnium isotopes in zircons". Geochimica et Cosmochimica Acta 55:849–859
  25. 1 2 3 Amelin YV, Lee DC, Halliday, A. N., Pidgeon RT (1999). "Nature of the Earth’s earliest crust from hafnium isotopes in single detrital zircons". Nature 399:252–255
  26. 1 2 3 Blichert-Toft J, Albarède F (2008). "Hafnium isotopes in Jack Hills zircons and the formation of the Hadean crust". Earth and Planetary Science Letters 265:686702
  27. 1 2 3 Turner, W., Heaman, L., & Creaser, R. (2003). "Sm-Nd fluorite dating of Proterozoic low-sulfidation epithermal Au-Ag deposits and U-Pb zircon dating of host rocks at Mallery Lake, Nunavut, Canada". Canadian Journal Of Earth Sciences40(12), 1789–1804.
  28. 1 2 3 4 5 6 Turner G, Harrison TM, Holland G, Mojzsis SJ, Gilmour J (2004). "Xenon from extinct 244Pu in ancient terrestrial zircons". Science 306:89–91
  29. 1 2 Tang, Rudnick, Mcdonough, Bose, & Goreva. (2017). "Multi-mode Li diffusion in natural zircons: Evidence for diffusion in the presence of step-function concentration boundaries". Earth and Planetary Science Letters474, 110–119.
  30. 1 2 Trail, D., Cherniak, D., Watson, J., Harrison, E., Weiss, B., & Szumila, T. (2016). "Li zoning in zircon as a potential geospeedometer and peak temperature indicator". Contributions to Mineralogy and Petrology171(3), 1–15.
  31. 1 2 3 4 Cimino, R., Rasmussen, & Neimark. (2013). "Communication: Thermodynamic analysis of critical conditions of polymer adsorption". The Journal of Chemical Physics, 139(20), The Journal of Chemical Physics, 28 November 2013, Vol.139(20).
  32. 1 2 3 4 5 Trail D, Cherniak DJ, Watson EB, Harrison TM, Weiss BP, Szumila I (2016). "Li zoning in zircon as a potential geospeedometer and peak temperature indicator". Contributions to Mineralogy and Petrology 171:1–15
  33. 1 2 3 Bell, Boehnke, & Harrison. (2017). "Corrigendum to 'Applications of biotite inclusion composition to zircon provenance determination' [Earth Planet. Sci. Lett. 473 (2017) 237–246]". Earth and Planetary Science Letters475, 267.
  34. 1 2 Hopkins M, Harrison TM, Manning CE (2010). "Constraints on Hadean geodynamics from mineral inclusions in > 4 Ga zircons". Earth and Planetary Science Letters 298:367–376
  35. 1 2 White RW, Powell RW, Holland TJB (2001). "Calculation of partial melting equilibria in the system Na2O–CaO– K2O–FeO–MgO–Al2O3–SiO2–H2O (NCKFMASH)". Journal of Metamorphic Geology 19:139–153
  36. 1 2 Rasmussen B, Fletcher IR, Muhling JR, Gregory CJ, Wilde SA (2011). "Metamorphic replacement of mineral inclusions in detrital zircon from Jack Hills Australia: Implications for the Hadean Earth". Geology 39:1143–1146
  37. 1 2 Trail D, Thomas JB, Watson EB (2011b). "The incorporation of hydroxyl into zircon". American Mineralogist 96:60–67
  38. 1 2 3 4 Abdel-Rahman, A. (1996). "Discussion on the Comment on Nature of Biotites in Alkaline, Calc-alkaline and Peraluminous Magmas". 37(5), 1031–1035.
  39. 1 2 Nutman, A., Mojzsis, S., & Friend, C. (1997). "Recognition of >=3850 Ma water-lain sediments in West Greenland and their significance for the early Archaean Earth". Geochimica Et Cosmochimica Acta,61(12), 2475-2484.
  40. 1 2 Rosing, M. (1999). "C-13-depleted carbon microparticles in > 3700-Ma sea-floor sedimentary rocks from west Greenland". Science,283(5402), 674–676.
  41. 1 2 3 4 Cherniak, D. J.; Watson, E. B. (August 2007). "Ti diffusion in zircon". Chemical Geology. 242 (3–4): 470–483. Bibcode:2007ChGeo.242..470C. doi:10.1016/j.chemgeo.2007.05.005.
  42. 1 2 3 4 Tailby, N. D.; Walker, A. M.; Berry, A. J.; Hermann, J.; Evans, K. A.; Mavrogenes, J. A.; O'Neill, H. St.C.; Rodina, I. S.; Soldatov, A. V.; Rubatto, D.; Sutton, S. R. (February 2011). "Ti site occupancy in zircon". Geochimica et Cosmochimica Acta. 75 (3): 905–921. Bibcode:2011GeCoA..75..905T. doi:10.1016/j.gca.2010.11.004.
  43. 1 2 Ferry, J. M.; Watson, E. B. (1 October 2007). "New thermodynamic models and revised calibrations for the Ti-in-zircon and Zr-in-rutile thermometers". Contributions to Mineralogy and Petrology. 154 (4): 429–437. Bibcode:2007CoMP..154..429F. doi:10.1007/s00410-007-0201-0. ISSN   0010-7999. S2CID   129429412.
  44. 1 2 Hopkins, M., Harrison, T., & Manning, C. (2012). "Metamorphic replacement of mineral inclusions in detrital zircon from Jack Hills, Australia; implications for the Hadean Earth; discussion". Geology (Boulder),40(12), E281-e281.
  45. 1 2 3 4 Alahakoon, Burrows, Howes, Karunaratne, Smith, & Dobedoe. (2010). "Fully densified zircon co-doped with iron and aluminium prepared by sol–gel processing". Journal of the European Ceramic Society,30(12), 2515–2523.
  46. ↑ Trail D, Tailby, N, Wang Y, Harrison TM, Boehnke P (2016). "Al in zircon as evidence for peraluminous melts and recycling of pelites from the Hadean to modern times". Geochemistry, Geophysics, Geosystems
  47. 1 2 Marty B, Alexander CMD, Raymond SN (2013) l. "Primordial origins of Earth's carbon". Reviews in Mineralogy and Geochemistry 75:149–181
  48. 1 2 Dasgupta R (2013). "Ingassing storage and outgassing of terrestrial carbon through geologic time". Reviews in Mineralogy and Geochemistry 75:183–229
  49. ↑ Clement, C.F; Harrison, R.G (July 1992). "The charging of radioactive aerosols". Journal of Aerosol Science. 23 (5): 481–504. Bibcode:1992JAerS..23..481C. doi:10.1016/0021-8502(92)90019-R.
  50. ↑ Gebauer, Dieter; Williams, Ian S.; Compston, William; Grünenfelder, Marc (January 1989). "The development of the Central European continental crust since the Early Archaean based on conventional and ion-microprobe dating of up to 3.84 b.y. old detrital zircons". Tectonophysics. 157 (1–3): 81–96. Bibcode:1989Tectp.157...81G. doi:10.1016/0040-1951(89)90342-9.
  51. 1 2 Schulze, Daniel J.; Harte, Ben; Valley, John W.; Brenan, James M.; Channer, Dominic M. De R. (1 May 2003). "Extreme crustal oxygen isotope signatures preserved in coesite in diamond". Nature. 423 (6935): 68–70. Bibcode:2003Natur.423...68S. doi:10.1038/nature01615. PMID   12721625. S2CID   4413573.
  52. ↑ Hawkesworth, Chris; Kemp, Tony (August 2006). "A zircon perspective on the evolution of the continental crust: Insights from combined Hf and O isotopes". Geochimica et Cosmochimica Acta. 70 (18): A236. Bibcode:2006GeCAS..70Q.236H. doi:10.1016/j.gca.2006.06.476.
  53. ↑ Taylor, D. J.; McKeegan, K. D.; Harrison, T. M.; Young, E. D. (1 June 2009). "Early differentiation of the lunar magma ocean . New Lu-Hf isotope results from Apollo 17". Geochimica et Cosmochimica Acta Supplement. 73: A1317. Bibcode:2009GeCAS..73R1317T. ISSN   0046-564X.
  54. ↑ Valley, John W.; Cavosie, Aaron J.; Ushikubo, Takayuki; Reinhard, David A.; Lawrence, Daniel F.; Larson, David J.; Clifton, Peter H.; Kelly, Thomas F.; Wilde, Simon A.; Moser, Desmond E.; Spicuzza, Michael J. (23 February 2014). "Hadean age for a post-magma-ocean zircon confirmed by atom-probe tomography". Nature Geoscience. 7 (3): 219–223. Bibcode:2014NatGe...7..219V. doi:10.1038/ngeo2075.
  55. 1 2 Valery K Brel; Namig S. Pirkuliev; Nikolai S. Zefirov (2001). "Chemistry of xenon derivatives. Synthesis and chemical properties". Russian Chemical Reviews. 70 (3): 231–264. Bibcode:2001RuCRv..70..231B. doi:10.1070/RC2001v070n03ABEH000626. ISSN   0036-021X. S2CID   250883131.
  56. ↑ Maas, Kinny, Williams, Froude, & Compston. (1992). The Earth's oldest known crust: A geochronological and geochemical study of 3900–4200 Ma old detrital zircons from Mt. Narryer and Jack Hills, Western Australia. Geochimica Et Cosmochimica Acta,56(3), 1281-1300.
  57. ↑ Pidgeon, & Nemchin. (2006). Comparative age distributions and internal structures of Archaean zircons from quartzites from Mt Narryer and the Jack Hills, Western Australia. Geochimica Et Cosmochimica Acta,70(18), A493.
  58. ↑ Nelson, Robinson, & Myers. (2000). Complex geological histories extending for ≥4.0 Ga deciphered from xenocryst zircon microstructures. Earth and Planetary Science Letters,181(1), 89-102.
  59. ↑ Wyche S (2007) Evidence of Pre-3100 Ma Crust in the Youanmi and South West Terranes, and Eastern Goldfields Superterrane, of the Yilgarn Craton. Dev Precambrian Geol 15:113–123
  60. ↑ Thern, & Nelson. (2012). Detrital zircon age structure within ca. 3Ga metasedimentary rocks, Yilgarn Craton: Elucidation of Hadean source terranes by principal component analysis. Precambrian Research,214-215, 28-43.
  61. ↑ Bowring SA, Williams IS (1999) Priscoan (4.00–4.03 Ga) orthogneisses from northwestern Canada. Contrib Mineral Petrol 134:3–16
  62. ↑ Stern RA, Bleeker W (1998) Age of the world’s oldest rocks refined using Canada’s SHRIMP the Acasta gneiss complex Northwest Territories Canada. Geosci Canada 25:27–31
  63. ↑ Mojzsis SJ, Cates NL, Caro G, Trail D, Abramov O, Guitreau M, Blichert-Toft J, Hopkins MD, Bleeker W (2014) Component geochronology in the polyphase ca. 3920 Ma Acasta Gneiss. Geochim Cosmochim Acta 133:68–96
  64. ↑ Mojzsis, S., & Harrison, T. (2002). Origin and significance of Archean quartzose rocks at Akilia, Greenland. Science, 298(5595), 917.
  65. ↑ Wilke, Schmidt, Dubrail, Appel, Borchert, Kvashnina, & Manning. (2012). Zircon solubility and zirconium complexation in H2O Na2O SiO2±Al2O3 fluids at high pressure and temperature. Earth and Planetary Science Letters,349-350, 15-25.
  66. ↑ Fei, Guangchun, Zhou, Xiong, Duo, Ji, Zhou, Yu, Wen, Chun-Qi, Wen, Quan, . . . Liu, Hongfei. (2015). Zircon U-Pb age and geochemical characteristics of ore-bearing granodiorite porphyry in the Duobuza porphyry copper deposit, Tibet. Journal of the Geological Society of India,86(2), 223-232.
  67. ↑ Diwu Chunrong, Sun Yong, Wang Hongliang, & Dong Zhengchan. (2010). A mineral record of 4.0 Ga metamorphism; evidence of metamorphic zircon xenocryst from western north Qinling orogenic belt. Geochimica Et Cosmochimica Acta,74(12), A237-A237.
  68. ↑ Cui, Pei-Long, Sun, Jing-Gui, Sha, De-Ming, Wang, Xi-Jing, Zhang, Peng, Gu, A-Lei, & Wang, Zhong-Yu. (2013). Oldest zircon xenocryst (4.17 Ga) from the North China Craton. International Geology Review,55(15), 1902-1908.
  69. ↑ Harrison TM, Schmitt AK (2007) High sensitivity mapping of Ti distributions in Hadean zircons. Earth Planet Sci Lett 261:9–19
  70. ↑ Nadeau S, Chen W, Reece J, Lachhman D, Ault R, Faraco MTL, Fraga LM, Reis NJ, Betiollo LM (2013) Guyana: the Lost Hadean crust of South America? Braz J Geol 43:601–606
  71. ↑ Paquette JL, Barbosa JSF, Rohais S, Cruz SC, Goncalves P, Peucat JJ, Leal ABM, Santos-Pinto M, Martin H (2015) The geological roots of South America: 4.1 Ga and 3.7 Ga zircon crystals discovered in NE Brazil and NW Argentina. Precambrian Res 271:49–55
  72. ↑ Sohma, T. (1999). Study of the Indian Shield: A Tectonic Model of Continental Growth. Gondwana Research,2(2), 311-312.
  73. ↑ Haraldur Sigurdsson. (1977). Generation of Icelandic rhyolites by melting of plagiogranites in the oceanic layer. Nature,269(5623), 25-28.
  74. ↑ François, Philippot, Rey, & Rubatto. (2014). Burial and exhumation during Archean sagduction in the East Pilbara Granite-Greenstone Terrane. Earth and Planetary Science Letters,396, 235-251.
  75. ↑ Plescia, J., & Cintala, M. (2012). Impact melt in small lunar highland craters. Journal of Geophysical Research: Planets,117(E12), N/a.
  76. ↑ Moore, W., & Webb, A. (2013). Heat-pipe Earth. Nature,501(7468), 501-5.
  77. ↑ Longhi, & Auwera. (1993). The monzonorite-anorthosite connection: The petrogenesis of terrestrial KREEP. Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 2: G-M, 897-898.
  78. ↑ These last two sentences make no sense. Please edit accordingly.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.