verb. 2009; Elardo et al. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. Moganite, a monoclinic SiO2 polymorph associated with carbonaceous chondrite-derived lunar alkaline fluid that becomes a source of subsurface ice deposits, has been identified along with the high-pressure polymorphs coesite in matrix grains and stishovite in some shock veins elsewhere in NWA 2727 (Kayama et al. 3c, d. In this part of the clast, fine pyroxene crystals (< 100 μm; Px fine1 in Fig. Although FG is variable in mineral assemblage, mineral zoning, and texture, the ferroan composition of mafic minerals is common in the FG lithology. Lassen (Lassen Peak), a prominent volcano and the key scenery in Lassen Volcanic National Park. 1983; Salpas et al. Privacy Dacite is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. Nature 477:70–72, Borg LE, Gaffney AM, Shearer CK, DePaolo DJ, Hutcheon ID, Owens TL, Ramon E, Brennecka G (2009) Mechanisms for incompatible-element enrichment on the Moon deduced from the lunar basaltic meteorite Northwest Africa 032. 2019, see their Figs. 2019), but the modal abundances of silica are less and grain sizes are smaller than silica of the silicic clast. Though the absolute age (or ages) of anorthosites in the highlands has been a topic of recent research (e.g., Borg et al. Mafic. 2c). 1991; Snyder et al. 9 for the comparison. 2a). 2018). Contrib Mineral Petrol 94:416–426, Hagerty JJ, Lawrence DJ, Hawke BR, Vaniman DT, Elphic RC, Feldman WC (2006) Refined thorium abundances for lunar red spots: implications for evolved, nonmare volcanism on the Moon. 2019). 9c. Prior to 1930 this cliff was known as Lava Cliffs. In: Proceedings of the 22nd Lunar and Planetary Science Conference, 1991, Houston, Texas, pp 399–416, Srinivasan P, Dunlap DR, Agee CB, Wadhwa M, Coleff D, Ziegler K, Zeigler R, McCubbin FM (2018) Silica-rich volcanism in the early solar system dated at 4.565 Ga. Nat Commun 9:3036, Streckeisen A (1979) Classification and nomenclature of volcanic rocks, lampro phyres, carbonatites, and melilitic rocks: recommendations and suggestions of the IUGS subcommission on the systematics of igneous rocks. Slow cooling facilitates the growth of large mineral crystals in the rock. 2018; Valencia et al. Geochim Cosmochim Acta 213:435–456, Shearer CK, Papike JJ, Spilde MN (2001) Trace-element partitioning between immiscible lunar melts: an example from naturally occurring lunar melt inclusions. The high Fe# and Ti# are consistent with late-stage crystallization in an igneous system (Fig. Dacite. Gruithuisen domes and Hansteen alpha are topographic highs, indicating that they may have formed from rhyolitic volcanism, whereas intrusive granites may be exposed at Lassell and parts of Aristarchus crater (see Head and McCord 1978 and Hawke et al. 2017). 1991; Marvin et al. J Geophys Res Planet 108:5069, Head JW, McCord TB (1978) Imbrian-age highland volcanism on the moon—the Gruithuisen and Mairan domes. It extends from northern California to Oregon, Washington State, and into British Columbia, Canada. 3d); and (3) elongate crystals intergrown with K-Ba-feldspar (labeled Si(3) in Fig. The basement rocks are granite, schist, and gneiss. We infer that this clast crystallized from silicic melt that formed by endogenic igneous processes on the Moon. Therefore, if the dacite formed from the alkali-silica-rich inclusions in the ARFe rocks, simple coalescence of inclusions alone is not a likely origin of the dacite. Detailed explanations of each figure are as follows: a photomicrograph in plane polarized light; b back-scattered electrons (BSE); c RGB elemental map with R = Al, G = Ca, B = Fe, d RGB image with R = K, G = Si, B = P. Silica occurs as: (1) massive to elongate grains; (2) narrow domains enveloping thin plagioclase feldspar laths; and (3) elongate crystals intercalated with K-Ba-feldspar. The “alkali”/Al2O3 ratio of the dacite clast (1.5) is over 1, and the value is within the range of “alkali”/Al2O3 values of most lunar granites/felsites (1.0–1.7 from Warren et al. Am Mineral 101:2312–2321, Gust DA, Arculus RJ (1986) Petrogenesis of alkalic and calcalkalic volcanic rocks of Mormon Mountain volcanic field, Arizona. Therefore, the formation of tridymite and cristobalite in the dacite clast by unloading after shock impact can be excluded; a shock melt origin of the dacite clast is unlikely. Symplectite clasts consist of fine, curved intergrown fayalite, hedenbergite, and silica. Oceanic crust is hydrothermally altered causing addition of quartz and sodium. Spatial continuity of variations within the FG lithology (ARFe rocks, symplectites, and pyroxene gabbro), combined with mineral compositions in the OG lithology and similar U-Pb ages of baddeleyite are strong evidence that these gabbroic rocks—OG, AG, FG lithologies—formed from a co-magmatic sequence of crystallization (Fagan et al. Parts of speech for Dacite. (2015) investigated the launch site of the NWA 773 using bulk composition, lunar global element maps (FeO, TiO2, and Th), and age constraints. Sci Adv 3:e1602365, Article  adjective. 2019). (Mg#51–70, see Table 4). (2015). Olivine and high-Ca pyroxene also occur in the clast, and Ca-phosphate, ilmenite, chromite, and troilite are present as minor minerals. 2018). 2014); and (3) fractional crystallization of basaltic liquid (e.g., Seddio et al. IUGS Classification of volcanic rocks (Streckeisen 1979). Dacite is a volcanic igneous rock which is rintermediate in composition between andesite and rhyolite. The symplectite (one variety of FG of Valencia et al. 2016). Progress in Earth and Planetary Science Based on the andesitic meteorites Graves Nunatak 06128/9 (GRA 06128/9; Day et al. Finally, although K-feldspar and silica are characteristic of the FG/ARFe clasts, they typically occur in minor modal abundances compared to mafic silicates. It is often found associated with andesite, and forms lava flows, dikes, and, in some cases, massive intrusions in the centres of old volcanoes. 2014; Kayama et al. Instead of gold, Carney found an abundance of copper stain. Some time during the 1930’s Lava Cliffs became known as Dacite Cliffs. 2016) supports the crustal melting model for the production of lunar granite from crustal protoliths by partial melting at temperatures below 1000 °C. Most of the mafic minerals occur in a cluster of olivine (310 μm × 260 μm), pyroxene, and apatite near the left margin of the clast as shown in Fig. White circle plot represents the silicic clast (this work). Conforms to HazCom 2012/United States Page 1 of 8 Safety Data Sheet Dacite Section 1. The authors declare that they have no competing interests. https://www.worldatlas.com/articles/andesite-facts-geology-of-the-world.html Factors controlling apatite vs. merrillite are in all likelihood connected to the relative abundances of volatile elements, which are concentrated in apatite, and of rare earth elements, which are concentrated in merrillite. 2003, 2014; Jolliff et al. Silica polymorphs were determined using micro-Raman spectroscopy in digital maps of three localities within the clast (Fig. Plagioclase often appears elongate in the OG clast, with grain sizes up to 1.3 × 0.3 mm. Share. All analyzed pyroxenes from the silicic clast have a Ti/Al ratio ranging from 0.4 to 0.6 with an average value of 0.5 as shown in Fig. 2019). PubMed Google Scholar. Examples of this type of dacite outcrop are found in northwestern Montana and northeastern Bulgaria.Nevertheless, because of the moderately high silica content, dacitic magma is quite viscous and therefore prone to explosive eruption. In: Proceedings of the 5th lunar science conference, 1974, Houston, Texas, pp 569–583, Rutherford MJ, Hess PC, Ryerson FJ, Campbell HW, Dick PA (1976) The chemistry, origin and petrogenetic implications of lunar granite and monzonite. It is often found associated with andesite, and forms lava flows, dikes, and, in some cases, massive intrusions in the centres of old volcanoes. Well-characterized oxides, silicates, and phosphates were used as standards. Previous work (Gullikson et al. Dacite. In addition to the OPB, other types of basaltic clasts with pyroxene phenocrysts have been found in the NWA 773 clan. Geology 7:331–335, Takeda H (1986) Mineralogy of Yamato 791073 with reference to crystal fractionation of the howardite parent body. J Japan Assoc Min Petr Econ Geol 80:119–127, Simon SB, Papike JJ, Laul JC (1988) Chemistry and petrology of the Apennine front, Apollo 15, part I: KREEP basalts and plutonic rocks. J Geophys Res 92:E340–E348, Seddio SM, Jolliff BL, Korotev RL, Carpenter PK (2014) Thorite in an Apollo 12 granite fragment and age determination using the electron microprobe. This work was supported in part by Research Fellowships for Young Scientists from the Japan Society for the Promotion of Science (JSPS) 18 J01786 (PI: Hiroshi Nagaoka) and by JSPS KAKENHI Grant Number 18H01298 (PI: Masahiro Kayama). Thus, among the possibilities discussed by Calzada-Diaz et al. 2014); granite/felsite (Quick et al. Mineral phases and modes were identified and determined based on the combined X-ray element maps. 1976; Fagan et al. The An value is higher than those of plagioclase in the Apollo granitic samples (An80–50; Wieczorek et al. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Pre-1991 sulfur transfer between mafic injections and dacite magma in the Mt. 1993; Fagan et al. Am Mineral 84:821–837, Jolliff BL, Gillis JJ, Haskin LA, Korotev RL, Wieczorek MA (2000) Major lunar crustal terranes: surface expressions and crust-mantle origins. Share. In: Proceedings of the 9th lunar and planetary science conference, 1978, Houston, Texas, pp 185–217, Weinberg RF, Hasalová P (2015) Water-fluxed melting of the continental crust: a review. The presence of BaO in zoned alkali feldspar of the dacite clast shows that some BaO was present in the igneous melt at the time of crystallization. 2005). 2014). However, this low-temperature crystallization model does not fit the dacite clast from NWA 2727 because the higher-temperature silica polymorphs cristobalite and tridymite occur along with quartz in the dacite. The dacite likely formed as evolved-melt pockets, and thus represents a. volumetrically minor lithology in the Vestan crust, although its formation provides direct. volume 7, Article number: 12 (2020) 1977; Warren and Wasson 1978; Warren et al. 2003; Valencia et al. In: Abstracts of the 37th lunar and planetary science conference, 2006, League city, Texas, p 1375, Calzada-Diaz A, Joy KH, Crawford IA, Nordheim TA (2015) Constraining the source regions of lunar meteorites using orbital geochemical data. 3c). Along with Dacite Formation, also learn about Dacite composition and transformation in the next section. The FeO content in plagioclase (1.15 wt%) is higher than those in the Apollo granite/felsite (0.06–0.79 wt%: Warren et al. The reported whole-rock Na2O and K2O (and SiO2) concentrations of the dacite in NWA 773 clan depend of course on the mode of the clast, which is likely to vary at least somewhat from the mode of the original lithology on the Moon. Dacite magma generally develops in subduction zones were a relatively young oceanic plate is subducting under a continental plate. The silicic clast occurs isolated in breccia, and has no spatial or zoning relationships with those gabbros. Meteorit Planet Sci 50:214–228, Campbell IH, Taylor SR (1983) No water, no granites—no oceans, no continents. 2006). 2003; Jolliff et al. Lunar meteorite NWA 2727 was found in Morocco or Algeria in 2005 (Connolly et al. These forces, particularly that of water, carried away the sedimentary rocks above and around the Tower. Furthermore, we compare the silicic clast with other silica-bearing lithic clasts of the NWA 773 clan and other lunar and terrestrial samples to consider implications of the clast for the origin of silica-bearing igneous rocks in general. All of the pyroxene analyses indicate hedenbergitic compositions with Fe# and Ti# both ≥ 99 (Ti# = molar Ti/[Ti + Cr] × 100) (Table 2; Figs. (2013) has a ferroan composition with fayalite and hedenbergite similar to the dacite clast and is interpreted as a product of extended fractional crystallization. 2003, in addition to Glotch et al. 2003; Zhang et al. This led him to believe he had a rich copper mine. Karymsky caldera was explosively formed 7900 yr BP as the result of eruption of 5–7 km 3 of dacite with collapse of Pra-Karymsky volcano (Braitseva and Melekestsev, 1991). Andesite… Some time during the 1930’s Lava Cliffs became known as Dacite Cliffs. Nevertheless, because of the moderate silica content, dacitic magma is quite viscous and therefore prone to explosive eruption. The bulk composition of the dacite clast is compared with those of other clast lithologies (OG, AG, FG, OPB) in NWA 773 clan and the Apollo quartz monzodiorite (QMD), granite, and felsite in Table 4. Meteorit Planet Sci 49:261–291, Etchepare J, Merian M, Smetankine L (1974) Vibrational normal modes of SiO2. 2003). 9–11 of FG-A, FG-B, FG-C, FG-D, FG-F, FG-I). Mineral abbreviations: Apa apatite, Fa fayalite, Ilm ilmenite, Kfs K-feldspar, Plg plagioclase, Px pyroxene, Si silica. The FG/ARFe clasts have curved inclusions of silica-rich feldspathic glass and/or silica + K-feldspar intergrowths. Geochim Cosmochim Acta Suppl 1:801–837, Rutherford MJ, Hess PC, Daniel GH (1974) Experimental liquid line of descent and liquid immiscibility for basalt 70017. 2019). Ternary diagram among SiO2, FeO + MgO + CaO, Na2O + K2O + Al2O3 (Seddio et al. 1988); QMD (Taylor et al. In future work, we will investigate the launch site of NWA 773 clan by comparing the geochemical and petrological data with imaging data with higher spatial resolution. 2011). Generally very fine-grained, porphyritic rhyolite to dacite in small, irregular-shaped bodies formed as subvolcanic intrusions in volcanic fields of southern and western Arizona, or in concentrated zones of dikes in the Mohave and Black Mountains of northwestern Arizona. 2010 and references therein). Geochim Cosmochim Acta 133:97–127, Fagan TJ, Taylor GJ, Keil K, Hicks TL, Killgore M, Bunch TE, Wittke JH, Mittlefehldt DW, Clayton RN, Mayeda TK, Eugster O, Lorenzetti S, Norman MD (2003) Northwest Africa 773: lunar origin and iron-enrichment trend. 1990; Jolliff et al. In: Abstracts of the 50th lunar and planetary science conference, 2019, the Woodlands, Texas, p 2270, Nagaoka H, Karouji Y, Takeda H, Fagan TJ, Ebihara M, Hasebe N (2015) Mineralogy and petrology of lunar meteorite Northwest Africa 2977 consisting of olivine cumulate gabbro including inverted pigeonite. The whole-rock composition distinguishes the dacite clast from other lunar silicic rocks such as QMD and granite. Dacite Magma. 2014), and crater counts indicate that basaltic volcanism continued in the PKT to at least 1.5 Ga (Hiesinger et al. Am Mineral 36:282–286, Roedder E, Weiblen PW (1970) Lunar petrology of silicate melt inclusions, Apollo 11 rocks. The presence of ferroan mafic silicates, silica, feldspar, and Ca-phosphates are common to the FG/ARFe lithology (combining the classification schemes of Fagan et al. Geochem Geophys Geosyst 1:2000GC000083, Valencia SN, Jolliff BL, Korotev RL (2019) Petrography, relationships, and petrogenesis of the gabbroic lithologies in Northwest Africa 773 clan members Northwest Africa 773, 2727, 3160, 3170, 7007, and 10656. Alkali feldspar is enriched in K, with minor Na, detectable Ca, and variable Ba (Ab3An2Or95Cn0–Ab4An2Or81Cn13). Silica minerals were not identified. 2a; 57 vol%) is the most abundant mineral in this OG clast. Science 283:1142–1145, Bence AE, Papike JJ, Prewitt CT (1970) Apollo 12 clinopyroxene: chemical trends. 2000; Grove and Krawczynski 2009). Plagioclase has chemical compositions near An87 with limited Ab-An zoning (An82–91; Table 3). The Apollo granite (12032,366-19) studied by Seddio et al. (2019). 1983; Morris et al. In Fig. Minor K2O (Or~ 2) was detected in all analyses of plagioclase and BaO was detected in some analyses, though only in minor concentrations (< 0.2 wt% BaO). I. α and β quartz. 1999; Hamasaki 2002; Horwell et al. 2014; Valencia et al. The dacite clast differs from the NWA 773 clan FG/ARFe clasts in the following: (1) plagioclase is more abundant than K-feldspar; (2) only apatite has been identified in the dacite clast, whereas the main Ca-phosphate in the ARFe lithology is merrillite; (3) feldspars and silica are much more abundant than mafic minerals in the dacite clast. Other silica-bearing igneous clasts in NWA 773 clan include clinopyroxene-phyric basalt (CPB) clasts, symplectite, and alkaline-phase-ferroan (ARFe) clasts (Fagan et al. 2a; 16 vol%) typically occur between coarse olivine and pyroxene. The occurrence of three low-pressure silica polymorphs indicates rapid, near-surface cooling, and disequilibrium. Quartz was identified only where silica is intergrown with K-Ba-feldspar, whereas cristobalite and tridymite were found where the silica has a more massive texture (Fig. One large basaltic clast, covering an area of 5.6 × 3.6 mm is present in the PTS (Fig. Haldar, in Platinum-Nickel-Chromium Deposits, 2017. 7). A potential immiscible pair of the dacite clast has not been identified, so partitioning of BaO between immiscible liquids cannot be assessed in detail. (2009), who reported an age of 2.99 ± 0.03 Ga, and by Nyquist et al. The clast is similar in some respects to ferroan gabbro alkaline-phase-ferroan (FG/ARFe) clasts that are inferred to be co-magmatic with olivine gabbro (OG) and other mafic lithologies of the NWA 773 clan. How is Andesite Formed? Geology.com 2015). The Cascade Range formed … Fe-oxides occur in trace abundances in the OG clast, and are located between coarse minerals. 1978; Taylor et al. 2011; Valencia et al. In contrast, the surface of the Moon is dominated by anorthositic rocks in the highlands and basaltic rocks in the lowlands. Olivine occurs as subhedral to euhedral crystals ranging from 100 μm up to 1.8 mm across. Terms and Conditions, 1991; Ryder and Martinez 1991; Jolliff et al. The clast was identified in Northwest Africa 2727 (NWA 2727), which is included in the NWA 773 clan. Pyroxene (dark green grains in Fig. Elements 5:29–34, Gullikson AL, Hagerty J, Reid MR, Rapp JF, Draper D (2016) Silicic lunar volcanism: testing the crustal melting model. Double ternary diagram which is used to classify igneous rocks based on mineralogic composition. Thin-section scale back-scattered electron (BSE) images and X-ray elemental maps were collected by an electron probe micro-analyzer (EPMA) (JEOL JXA-8900) at Kobe University. Peralta Road is a non-surfaced road, but is well maintained. The glass in Y-983885 apparently represents a case of silica-enrichment followed by rapid cooling distinct from the origin of the dacite clast in NWA 2727. This feud resulted in the death of Eli Koreavitch one of the miners who worked for Pete Carney. Thus, it is likely that all of the pyroxene from the clast crystallized after the onset of feldspar crystallization. How is quartz formed in rocks? These 'ages' are, of course, preposterous. The main Ca-phosphate in the FG/ARFe lithology is merrillite, whereas only apatite has been identified in the dacite clast. Plagioclase (red in Fig. Immiscibility has been discussed as a possible explanation for the formation of lunar granites and the absence of intermediate lithologies (e.g., Jolliff 1991; Seddio et al. His best known work is a book of Arizona poems. In: Proceedings of the 4th lunar science conference, 1973, Houston, Texas, pp 1127–1148, Roedder E (1951) Low temperature liquid immiscibility in the system K2O-FeO-Al2O3-SiO2. 2015) were detected. Nature 457:179–182, Elardo SM, Shearer CK Jr, Fagan AL, Borg LE, Gaffney AM, Burger PV, Neal CR, Fernandes VA, McCubbin FM (2014) The origin of young mare basalts inferred from lunar meteorites Northwest Africa 4734, 032, and LaPaz Icefield 02205. 9, the bulk composition of the dacite clast is compared with lunar evolved rocks returned by Apollo missions (KREEP basalt, QMD, granite/felsite, granitic breccia) (Hubbard et al. Earth Planet Space 54:217–229, Hawke BR, Lawrence DJ, Blewett DT, Lucey PG, Smith GA, Spudis PD, Taylor GJ (2003) Hansteen alpha: a volcanic construct in the lunar highlands. Plagioclase in the clast (35 vol%) is more abundant than in the OG lithology (16 vol%). S.K. All the spectral data were calibrated by monitoring the position of the O-Si-O bending vibration (464 cm−1) in reference standard quartz of high optical grade before and after each measurement. From study of meteorites from asteroid 4 Vesta, dacite formation occurred on Vesta by crustal partial melting (Hahn Jr. et al. Another possible factor in the origin of the dacite is silicate liquid immiscibility (SLI). Formation of ferroan dacite by lunar silicic volcanism recorded in a meteorite from the Moon. HN proposed the topic, conceived and designed the study. Petrologic description of samples of lunar silicic rocks is an essential step toward evaluating the igneous processes that led to granite formation on the Moon and other celestial bodies. However, terrestrial A-type or ferroan granitoids are characterized by more anhydrous conditions (Frost and Frost 2011), and share some similarities in mineralogy, chemistry, and possibly origin with granitic rocks on differentiated bodies other than the Earth (Bonin 2012). 1992; Seddio et al. 2019). Some of FG clasts (symplectite and ARFe) in other portions of NWA 773 clan include silica minerals (Fagan et al. Trachyte; Trachyte is a extrusive igneous rock that light coloured is composed mostly of alkali feldspar with minor amount of dark coloured minerals such as biotite, amphibole, or pyroxene. Obsidian has a glassy lustre and is slightly harder than window glass. Large olivine crystals with pyroxene and plagioclase filling interstices indicate the cumulate texture. The basement rocks are granite, schist, and gneiss. On the IUGS classification of volcanic rocks based on modal abundances of silica, alkali feldspar, and plagioclase, this clast falls on the boundary between rhyolite and dacite (Fig. 1983). It is composed predominantly of plagioclase Geol Soc Am Bull 125:1079–1113, Bunch TE, Wittke JH, Korotev RL, Irving AJ (2006) Lunar meteorites NWA 2700, NWA 2727 and NWA 2977: Mare basalts/gabbro breccias with affinities to NWA 773. 3c), and one coarser crystal (210 μm × 140 μm) occurs near the bottom of the clast (Px crs in Fig. On Earth, igneous processes in diverse geochemical settings have resulted in wide compositional ranges of mafic to silicic rocks which form the crust. Bull Volcanol 72:249–253, Hubbard NJ, Rhodes JM, Gast PW, Bansal BM, Shih C-Y, Wiseman H, Nyquist LE (1973) Lunar rock types: the role of plagioclase in non-mare and highland rock types. In addition to the large pyroxene gabbro clast, other FG lithologies are present as smaller clasts in the PTS and in other specimens of NWA 2727 (Bunch et al. Pyroxene (dark green in Fig. Fine pyroxene crystals that are interwoven with apatite in the mafic cluster and the coarse pyroxene have essentially identical Wo-En-Fs compositions; the fine pyroxene near the upper right margin (Px fine2 in Fig. White circle plot represents the dacite clast (this work). Photoshop was also used to estimate the area fraction (mode) of minerals from elemental maps covering approximately 3 mm2 in the silicic clast by counting pixels of each phase, which is taken to be proportional to the volume fraction. 2018). Carney believed the Dacite Cliffs contained a fortune. Dacite is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. 2016). The Chao dacite is a type of lava dome known as a coulée. Hiroshi Nagaoka. 2006; Glotch et al. 2001) in addition to the evidence from the NWA 773 clan described above. Meterorit Planet Sci 52:1173–1196, Hamasaki S (2002) Volcanic-related alteration and geochemistry of Iwodake volcano, Satsuma-Iwojima, Kyusyu, SW Japan. By Categories In미분류 Posted on On 26 12월 2020 Categories In미분류 Posted on On 26 12월 2020 2013). Earth Planet Sci Lett 451:149–158, Snyder GA, Taylor LA, Liu Y-G, Schmitt RA (1992) Petrogenesis of the western highlands of the Moon: evidence from a diverse group of whitlockite-rich rocks from the Fra Mauro formation. The last eruptions formed Shastina's present summit about a hundred years later. Astrophys J 778:60. https://doi.org/10.1088/0004-637X/778/1/60, Le Bas MJ, Le Maitre RW, Woolley AR (1992) The construction of the total alkali-silica chemical classification of volcanic rocks. 2d). Olivine (light green grains in Fig. 2019): pyroxene gabbro, symplectite clasts, and alkaline-phase-ferroan (ARFe) clasts (Fagan et al. 2007; Valencia et al. The acronym, QAPF, stands for "Quartz, Alkali feldspar, Plagioclase, Feldspathoid (Foid)". Dacite (/ ˈ d eɪ s aɪ t /) is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. Dacite usually forms as an intrusive rock such as a dike or sill. Wikipedia. A notorious example of this is Mount St. Helens in which dacite domes formed from previous eruptions. The Raman peak intensity maps show the following peaks: e peak intensity at 351 cm−1 (tridymite); f peak intensity at 411 cm−1 (cristobalite); g peak intensity at 411 cm−1 (cristobalite); h peak intensity at 464 cm−1 (quartz). 2019): olivine gabbro (OG, an olivine-pyroxene-plagioclase-rich rock); anorthositic gabbro (AG, a plagioclase-rich rock with some pyroxene); and ferroan gabbro (FG, a group of lithologies all having high Fe# = molar Fe/[Fe + Mg]; see below). The presence of multiple types of basalts indicates that some clasts of the NWA 773 clan formed initially from variable types of volcanism. 3). The partitioning of Ba between Fe-rich and Si-alkali-rich immiscible liquids depends on the molar (Na2O + K2O + CaO + BaO)/Al2O3 ratio in the granitic immiscible melt. 1970; Fagan et al. 1992). Both types of inclusions in the FG/ARFe clasts formed by silicate liquid immiscibility after Fe-enrichment. The company was incorporated on July 28, 1909. Although there are mineralogical and compositional differences between the dacite and FG/ARFe lithology described by Fagan et al. Silica occurs as (1) massive to elongate grains up to 550 μm in long diameter (labeled Si(1) in Fig. Earth Planet Space 67:200. https://doi.org/10.1186/s40623-015-0368-y, Neal CR, Taylor LA (1989) The nature of barium partitioning between immiscible melts: a comparison of experimental and natural systems with reference to lunar granite petrogenesis. 2014; Valencia et al. But before that, Shastina, along with the then forming Black Butte dacite plug dome complex to the west, created numerous pyroclastic flows that covered 43 sq mi (110 km2), including large parts of what is now Mount Shasta, California and Weed, California. 2006; Valencia et al. The silicic clast is 2.2 × 1.3 mm in size in this PTS. Nonetheless, the presence of granitic rocks is an indicator of compositional evolution by igneous processes in the Moon. 2011; Barboni et al. Diorite is a coarse-grained igneous rock that forms when the magma remains below Earth's surface and cools slowly. From the above results, the dacite clast appears to be a distinct lithology from the existing lithologies in the NWA 773 clan. Icarus 211:101–113, Marvin UB, Lindstrom MM, Holmberg BB, Martinez RR (1991) New observations on the quartz monzodiorite-granite suite.