U–Pb SHRIMP zircon geochronology, petrogenesis, and tectonic setting of the Neoproterozoic Baekdong ultramafic rocks in the Hongseong Collision Belt, South Korea

Oh, Chang Whan; Seo, Jung-Kil; Choi, Seon Gyu; Rajesh, V.J.; Lee, J.H.

doi:10.1016/j.lithos.2011.10.008

Cited by 27 publications

(9 citation statements)

References 47 publications

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“…In recent time, an advance in this field has been made owing to the elaboration of methods for dating zircon grains with application of high-resolution secondary-ion mass spectrometers (SHRIMP-II). Today, these methods are used for isotope dating of not only zircons from granitoids (Rudnev et al, 2012), alkaline igneous rocks (Vrublevskii et al, 2014), and metamorphic rocks (Turkina et al, 2014) but also zircons from gabbroids (Bortnikov et al, 2008;Krasnobaev et al, 2007;Ledneva et al, 2012;Skolotnev et al, 2010;Tsukanov and Skolotnev, 2010) and ultramafites (Badanina and Malich, 2012;Fershtater et al, 2009;Knauf, 2008;Lesnov et al, 2010;Malitch et al, 2009;Oh et al, 2012;Ronkin et al, 2013).…”

Section: Results Of Isotope-geochronological Studies Of Zirconsmentioning

confidence: 99%

Polygenesis of mafic–ultramafic complexes: Isotope-geochronological and geochemical evidence from zircons of the Berezovka massif rocks (Sakhalin Island)

Lesnov

Хлестов

Gal’versen

et al. 2015

Russian Geology and Geophysics

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Results of comprehensive isotope-geochronological (U-Pb dating; SHRIMP II) and geochemical (LA-ICP-MS) studies of zircons from different rocks of the Berezovka polygenetic mafic-ultramafic massif of the East Sakhalin ophiolite association are presented. The massif includes three proximal but genetically autonomous structure-lithologic complexes of different ages: protrusion of ultramafic rocks of restite nature, gabbroid intrusion breaking through it, and contact reaction zone located along their boundaries. The isotopic age of zircons in the massif as a whole and in its individual rocks varies over a broad range of values. The zircons belong to several populations according to their age (Ma) and other features: relict and xenogenous (~3100-990, 70-410, and ~395-210) and syngenetic (~200-100, ~90-65, and ~30-20). They differ in grain size and morphology, optical and cathodoluminescence images, and trace-element patterns. By morphology, the grains are divided into short-prismatic crystals with well-developed faces and edges, long-prismatic crystals with well-developed faces and edges, prismatic crystals with slightly resorbed faces and edges, prismatic crystals with strongly resorbed faces and edges, and intensely resorbed grains totally or partly lacking faceting. The ages of zircons depend inversely on the contents of La, Ce, and Yb, total contents of REE, (Ce/Ce*) n , and (Eu/Eu*) n . Some grains are characterized by abnormal REE and trace-element patterns due to their epigenetic redistribution. The wide scatter of the intermediate ages of relict and xenogenous zircon grains, their resorption and disturbed optical and geochemical features are probably due to the nonuniform rejuvenation of their isotope systems and variations in other parameters, caused by the effect of younger mafic melt and its fluids, whose crystallization gave rise to a gabbroid intrusion dated at 170-150 Ma. The obtained data on the isotopic age and other properties of zircons from the rocks of the Berezovka massif agree with the geological model of its polygenesis.

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Section: Results Of Isotope-geochronological Studies Of Zirconsmentioning

confidence: 99%

Polygenesis of mafic–ultramafic complexes: Isotope-geochronological and geochemical evidence from zircons of the Berezovka massif rocks (Sakhalin Island)

Lesnov

Хлестов

Gal’versen

et al. 2015

Russian Geology and Geophysics

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“…In the previous studies, spinel has been regarded as an effective indicator of the tectonic settings of basic-ultrabasic rocks. However, researchers are more inclined to use the content of Mg#, Cr#, Al 2 O 3 , and Fe 2 O 3 for discriminating (Arai, 1994;Barnes & Roeder, 2001;Franz & Wirth, 2000;Ishwar-Kumar et al, 2016;Jan & Windley, 1990;Kamenetsky, Crawford, & Meffre, 2001;Maurel & Maurel, 1982;Oh, Seo, Choi, Rajesh, & Lee, 2012;Tamura & Arai, 2006). Only a few researchers think that TiO 2 is also a useful indicator (Dharma Rao, Santosh, Kim, & Li, 2013;Leterrier, Maury, Thonon, Girard, & Marchal, 1982).…”

Section: Discussionmentioning

confidence: 99%

Discriminating among tectonic settings of spinel based on multiple machine learning algorithms

Han

Ren

2019

Big Earth Data

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In geochemistry, researchers usually discriminate among tectonic settings by analyzing the chemistry elements of minerals. Previous studies have generally taken spinel and monoclinic pyroxene as subjects. Therefore, in this research, we took spinel as a breakthrough. Totally 1898 spinel samples with 14-dimension chemistry elements were collected from three different tectonic settings, including ocean island, convergent margin, and spreading center. In the experiment, 20 classification algorithms were conducted in the classification learner application of MATLAB. The validation accuracies, receiver operating characteristic curves (ROCs), and the areas under ROC curve (AUCs) show that the Bag Ensemble Classifier has the best performance in the problem. Its validation accuracy is 86.3%, and the average AUC is 0.957. For further analysis, we studied the importance of different major elements in discriminating. It has been found that TiO 2 has the best impact on discrimination, and FeO T , Al 2 O 3 , Cr 2 O 3 , MgO, MnO, and ZnO are of less importance. Based on the Bag Ensemble Classifier, a MATLAB plug-in application named Discriminator of Spinel Tectonic Setting (DSTS) has been developed for promoting the usage of machine learning in geochemistry and facilitating other researchers to use our achievements.

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“…The discoveries of the sedimentation during the great-hiatus period of long-held belief (Cho, 2007;Choi et al, 2008) and widespread Neoproterozoic events (e.g., Lee, K.-S. et al, 1998;Lee, S.R. et al, 2003;Oh et al, 2012) would be the most familiar examples.…”

Section: Introductionmentioning

confidence: 99%

Recognition of the Phanerozoic “Young granite gneiss” in the central Yeongnam massif

et al. 2014

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Up to now, all the high-grade gneisses of the Korean peninsula have been regarded as Precambrian basement rocks and presence of the Phanerozoic high-grade metamorphic rocks have remained unknown. However, such granite gneiss is discovered through this study from the central Yeongnam massif near Gimcheon. SHRIMP zircon U-Pb age determinations on the granite gneiss, having well-developed gneissic foliations and migmatitic textures, reveal concordant age of ca. 250 Ma indicating the Early Triassic emplacement of this pluton, which is in contradict to the previous belief that it is a Precambrian product. Even though the granite gneiss reveals well-developed gneissic foliations and some zircons show rather low Th/U ratios, the metamorphic age has not been determined successfully. However, the age of metamorphism can be constrained as middle Triassic considering the absence of any evidences of metamorphism from the nearby granitic plutons having emplacement ages of ca. 225 Ma. Early Triassic emplacement and subsequent Middle Triassic metamorphism of the granite gneiss from the Yeongnam massif bear a remarkable resemblance to the case of South China block. We suggest the possibility that Early to Middle Triassic metamorphism of the Korean peninsula might be products of the intracontinental collisional events not directly related with the Early Triassic continental collision event.

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U–Pb SHRIMP zircon geochronology, petrogenesis, and tectonic setting of the Neoproterozoic Baekdong ultramafic rocks in the Hongseong Collision Belt, South Korea

Cited by 27 publications

References 47 publications

Polygenesis of mafic–ultramafic complexes: Isotope-geochronological and geochemical evidence from zircons of the Berezovka massif rocks (Sakhalin Island)

Polygenesis of mafic–ultramafic complexes: Isotope-geochronological and geochemical evidence from zircons of the Berezovka massif rocks (Sakhalin Island)

Discriminating among tectonic settings of spinel based on multiple machine learning algorithms

Recognition of the Phanerozoic “Young granite gneiss” in the central Yeongnam massif

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