Oxygen Isotopic Compositions of the <scp>C</scp>ape <scp>A</scp>shizuri Granitoids in Southwest <scp>J</scp>apan

Ishihara, Shunsō; Qin, Kezhang

doi:10.1111/rge.12054

Cited by 4 publications

(3 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Contamination of upper crustal materials into biotite granites of stage IV was suggested on the basis of its relatively high radiogenic Sr isotope ratio (Murakami et al, ). Whole‐rock oxygen isotope ratios indicate that alkaline granites and gabbros were lower crust and upper mantle in origin, respectively (Ishihara & Qin, ).…”

Section: Methodsmentioning

confidence: 99%

Geochemical characteristics of zircons in the Ashizuri A‐type granitoids: An additional granite topology tool for detrital zircon studies

et al. 2017

View full text Add to dashboard Cite

Zircon is resistant to alteration over a wide range of geological environments, and isotopic ratios within the mineral provide constraints on ages and their parental magmas. Trace element compositions in zircon are also expected to reflect those of their parent magmas, and have a potential as essential indicators for their host rocks. Because most detrital zircons that accumulate at river mouths are derived primarily from granitoids, the classification of zircon within granitoids is potentially meaningful. This study employs the conventional classification scheme of granites (I-, S-, M-, and A-types). To clarify geochemical characteristics of zircons in A-type granites, trace element compositions of zircons extracted from the A-type Ashizuri granitoids were examined. Zircons from the Ashizuri granitoids commonly show enrichments of heavy rare earth elements and positive Ce anomalies, indicating that these zircons were igneous in origin. In addition, zircons in these A-type granites are characterized by enrichments of Nb, Y, Ta, Th, and U and strong negative Eu anomalies, which exhibit good positive correlations with those in their whole rocks. This fact indicates that these signatures in zircons reflect well those in their parental bodies and are useful in identifying zircons derived from A-type granite. Based on compilations of available data, zircons from A-type granites can be clearly discriminated from other-types of granites within Nb/Sr-Eu anomaly, U/Sr-Eu anomaly, Nb/Sr-U/Sr, and Nb/Sr-Ta/Sr cross-plots. All indices used in these diagrams were selected based on the geochemical features of both zircon and whole rock of A-type granites. Application of these discrimination diagrams to detrital zircons will likely provide further insights. For example, some Hadean detrital zircons plot in similar fields to A-type granites, implying the existence of A-type magmatism in the Earth's earliest history. K E Y W O R D SAshizuri, A-type granite, HFSE, REE, zircon | INTRODUCTIONZircons are often used as geochronological and geochemical indicators for constraining the nature of their host rocks. Recent developments of analytical methods enable us to extract information concerning the host rock from a single zircon grain. As one such example, contribution rates of mature sediments into granitoid magma through geologic time have been examined based on compilations of oxygen isotope ratios of zircons extracted from granites (Valley et al., 2005) and of detrital zircons in river mouth sands (Iizuka et al., 2013). Belousova, Griffin, O'Reilly, and Fisher (2002) examined trace element contents in zircons from a variety of rock types and proposed some discrimination diagrams, but found that most rocks are inseparable except for peculiar rocks (kimberlite, carbonatite, and nepheline-syenite). Basically, most detrital zircons that accumulate at river mouths are derived primarily from granitoids (Hawkesworth, Cawood, Kemp, Storey, & Dhuime, 2009), and their U-Pb age populations reflect the age variation of the hinterlan...

show abstract

Section: Methodsmentioning

confidence: 99%

Geochemical characteristics of zircons in the Ashizuri A‐type granitoids: An additional granite topology tool for detrital zircon studies

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Although numerous zircon U-Pb age data of the granitic rocks are available in the literature (Herzig et al, 1998;Watanabe et al, 2000;Nakajima et al, 2004;Ishihara and Tani, 2013;Iida et al, 2015;Skrzypek et al, 2016;Sueoka et al, 2016;Takatsuka et al, 2018a;Takatsuka et al, 2018b;Miyazaki et al, 2018;Shimooka et al, 2019;Mateen et al, 2019;Nakae, 2021;Noda et al, 2021;Tsutsumi 2021), limited number of those from mafic plutonic rocks, which probably reflect mantle activity directly, has been reported (Nakajima, et al, 2004).…”

Section: A C C E P T E D I N J M P S P R E -P R O O Fmentioning

confidence: 99%

Zircon U-Pb ages of the Cretaceous gabbroic and granitic rocks from the Kajishima, northwest Shikoku, southwest Japan

Shimooka¹,

Saito²,

Tani³

2023

Journal of Mineralogical and Petrological Sciences

View full text Add to dashboard Cite

We carried out zircon U-Pb dating of the Cretaceous gabbroic and granitic rocks exposed in the Kajishima to determine their magmatic ages. The plutonic rocks in the Kajishima are classified into seven lithologies: Hbl-bearing olivine norite, Type-1 Hbl-bearing troctolite, Type-2 Hblbearing troctolite, Type-1 pyroxene hornblende gabbronorite, and Type-2 pyroxene hornblende gabbronorite, massive granodiorite, and deformed granodiorite. The new zircon U-Pb ages are: 90.77 ± 0.99 Ma for the Type-2 Hbl-bearing troctolite, 92.35 ± 0.74 Ma for the Type-1 pyroxene hornblende gabbronorite, 91.33 ± 1.03 Ma for the massive granodiorite, and 84.11 ± 1.12 Ma for the deformed granodiorite. The new zircon U-Pb ages suggest multiple episodes of magmatic intrusion in Kajishima during ~92 Ma and 84 Ma. Although two gabbroic rocks and a massive granodiorite show similar zircon U-Pb ages, subsequent granitic magmatism is unraveled in Kajishima, which is contrary to previous geological studies that postulated an

show abstract

“…Murakami et al (1989) suggested that, based on the geochemical characteristics and the low values of initial radiogenic Sr isotopes, the parental magmas of these granitoids were derived from the mantle or arc lower crust. Whole‐rock oxygen‐isotope ratios indicate that the alkaline granites and gabbros originated in the lower crust and upper mantle, respectively (Ishihara & Qin, 2015). To account for both the elemental and isotopic features of the Ashizuri plutonic rocks, Stein et al (1996) ascribed the origin of the Ashizuri plutonic complex to an OIB‐like enriched source.…”

Section: Geological Backgroundmentioning

confidence: 99%

Zircon trace‐element compositions in Miocene granitoids in Japan: Discrimination diagrams for zircons in M‐, I‐, S‐, and A‐type granites

et al. 2022

View full text Add to dashboard Cite

Detrital zircons demonstrate high resistance to alteration and, as such retain information about their formation ages and parental magmas for a long period of time.Geochemical researchers have proposed a wide variety of discrimination diagrams applicable to detrital zircons. In our research, we focused on the conventional classification scheme for granites (Mantle, M; Igneous, I; Sedimentary, S; and Alkaline, A types) and sought to characterize zircon trace-element compositions that are sensitive to differences among these granite types. To accomplish this, we examined trace-element compositions of zircons extracted from granitoids in the Ohmine granitic rocks and the Ashizuri plutonic complex in southwestern Japan.The zircons showed systematic differences in Nb/P, Ta/P, Ce/P, Ce/Nd, Y/P, Th/U, and Sc/Yb ratios and the Eu anomaly. Zircons in A-type granite are rich in Nb, Ta, Ce, and Y, and their signatures clearly reflect those elements in their parental bodies. Sc/Yb ratios of zircons in A-type granites are <0.1, which is similar to those of ocean-island-type zircons. Despite their high abundance at the wholerock level, zircons in S-type granite are characterized by low Nb/P, Ta/P, and Th/U ratios. This is attributable to the depletion of Nb, Ta, and Th in the magma by ilmenite and monazite prior to zircon crystallization. In general, S-type granitic magmas exhibit reducing environments, which decrease the proportions of Ce 4+ and Eu 3+ . These effects lead to a low Ce/Nd ratio and a large negative Eu anomaly in S-type zircons. On the basis of these findings, we recommend the combined use of Nb/P-Ce/P or Ta/P-Ce/P crossplots and of Sc/Yb ratios to discriminate zircons in M-, I-, S-, and A-type granites. Although the crossplots are created using data from Miocene granitoids in Japan, the discrimination diagrams are based on the general features of each type of granite.

show abstract

Oxygen Isotopic Compositions of the Cape Ashizuri Granitoids in Southwest Japan

Cited by 4 publications

References 16 publications

Geochemical characteristics of zircons in the Ashizuri A‐type granitoids: An additional granite topology tool for detrital zircon studies

Geochemical characteristics of zircons in the Ashizuri A‐type granitoids: An additional granite topology tool for detrital zircon studies

Zircon U-Pb ages of the Cretaceous gabbroic and granitic rocks from the Kajishima, northwest Shikoku, southwest Japan

Zircon trace‐element compositions in Miocene granitoids in Japan: Discrimination diagrams for zircons in M‐, I‐, S‐, and A‐type granites

Contact Info

Product

Resources

About