Upper Paleozoic and Mesozoic strata in the northeastern part of the Mino Terrane, Nagano Prefecture, central Japan

Otsuka, Tsutomu

doi:10.5575/geosoc.91.583

Cited by 8 publications

(3 citation statements)

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“…Such a sequence is regarded to be one type of the 'chert-clastics sequence' (CCS) documented by Matsuoka (1984), which is a typical example of oceanic plate stratigraphy. This sequence generally begins with siliceous claystone and is conformably overlain by chert, siliceous mudstone, mudstone and coarser clastic rocks such as sandstone or alternating bed of sandstone and mudstone (e.g., Matsuoka, 1984;Otsuka, 1985). In the Daigo district, the typical sequence is observed at several localities.…”

Section: Pgs Laminated Msmentioning

confidence: 99%

Stratigraphy and structure of the Jurassic accretionary complex in the Daigo district, northern Ibaraki and eastern Tochigi Prefectures, central Japan

Nakae

2006

Bull. Geol. Surv. Japan

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Stratigraphy and structure of the Jurassic accretionary complex in the Daigo district, northern Ibaraki and eastern Tochigi Prefectures, central JapanSatoshi Nakae (2006) Stratigraphy and structure of the Jurassic accretionary complex in the Daigo district, northern Ibaraki and eastern Tochigi Prefectures, central Japan. Bull. Geol. Surv. Japan, vol. 57 (1/2), 29-50, 21 figs, 3 tables. Abstract:The Daigo district covers nearly 420 km 2 in the northern Ibaraki and eastern Tochigi Prefectures, central Japan, about 150 km NNE of Tokyo. The district is topographically distinguished into three areas: in the northeast the Abukuma Mountains, in the central area the dissected lowland and hills, and in the west the Yamizo Mountains. The Abukuma Mountains are separated from the central lowland and hills by the Tanagura tectonic line (TTL). East of the tectonic line, the Abukuma Mountains are mainly underlain by Cretaceous metamorphic and granitic rocks of the Abukuma belt. To the west, accretionary complexes of the Ashio belt ranging from Triassic to probably earliest Cretaceous in age and unconformably overlying Miocene sedimentary and volcanic rocks are respectively exposed in the west and central areas. The mapped area is located in the Yamizo Mountains.The Yamizo Mountains are mainly underlain by a disrupted and dismembered accretionary complex of various depositional environments ranging from pelagic to terrigenous. The accretionary complex, called the Ashio Terrane, is thought to have been formed along a convergent margin where the Izanagi plate was subducting beneath the ancient Asian continent during the Jurassic period. The Ashio Terrane in this district is tectonostratigraphically subdivided into the Kasama and Takatori Complexes; their lithologic features are almost similar, but the variety and/or abundance of their component rocks, age of deposition and tectonic contact with the complexes can provide the basis for classification.The Kasama Complex is mainly composed of clastic rocks such as massive to stratified sandstone, laminated mudstone, silty mudstone and pelagic chert. Among these rocks, massive sandstone and laminated mudstone are most dominant, and chert is rarely included in the complex. Pelitic mixed rock, which consists of foliated black mudstone with pebbles or lenticular small blocks of sandstone and chert, is also observed. The Takatori Complex is almost similar to the Kasama Complex in lithology as a whole, however the sequence of laterally extending cherts and overlying clastic rocks of mudstone and sandstone is repeatedly exposed at least three times in this complex. The thickness of each complex is thought to be about 4,000 m.The Kasama Complex is inferred to be in fault contact with the overlying Takatori Complex. These complexes gently to moderately dip westward. Post-Jurassic folding is represented by the strike obviously swinging from NE-SW to NW-SE. Furthermore numerous subvertical faults, NNW-SSE and NE-SW trending, transect the complexes.

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Section: Pgs Laminated Msmentioning

confidence: 99%

Stratigraphy and structure of the Jurassic accretionary complex in the Daigo district, northern Ibaraki and eastern Tochigi Prefectures, central Japan

Nakae

2006

Bull. Geol. Surv. Japan

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“…Currently, the genus Symplocarpus comprises six species ( S. foetidus , S. renifolius , S. nipponicus , S. nabekuraensis , S. koreanus , and S. egorovii ), half of which have been newly identified and described in the last 20 years (Lee et al, 2021 ; Otsuka et al, 2002 ; Pavlova & Nechaev, 2005 ). As mentioned above, S. foetidus and S. renifolius are well‐known for their remarkable heat‐producing abilities (Ito‐Inaba et al, 2009 ; Knutson, 1974 ).…”

Section: Introductionmentioning

confidence: 99%

Potential contribution of floral thermogenesis to cold adaptation, distribution pattern, and population structure of thermogenic and non/slightly thermogenic Symplocarpus species

Sato

Matsuo

Otsuka

et al. 2023

Ecology and Evolution

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The genus Symplocarpus in basal Araceae includes both thermogenic and non/ slightly thermogenic species that prefer cold environments. If floral thermogenesis of Symplocarpus contributes to cold adaptation, it would be expected that thermogenic species have a larger habitat than non/slightly thermogenic species during an ice age, leading to increased genetic diversity in the current population. To address this question, potential distribution in past environment predicted by ecological niche modeling (ENM), genetic diversity, and population structure of chloroplast and genome-wide single nucleotide polymorphisms were compared between thermogenic Symplocarpus renifolius and non/slightly thermogenic Symplocarpus nipponicus. ENM revealed that the distribution of S. nipponicus decreased, whereas that of S. renifolius expanded in the Last Glacial Maximum. Phylogeographic analyses have shown that the population structures of the two species were genetically segmented and that the genetic diversity of S. renifolius was higher than that of S. nipponicus. The phylogenetic relationship between chloroplast and nuclear DNA is topologically different in the two species, which may be due to the asymmetric gene flow ubiquitously observed in plants. The results of this study imply that floral thermogenesis of Symplocarpus contributes to expanding the distribution during an ice age, resulting in increased genetic diversity due to cold adaptation.

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“…Microfossil (conodont and radiolarian) biostratigraphy coupled with detailed field investigations has made it possible to discuss the internal structure and formative processes of an accretionary complex a t convergent margins between continental and oceanic plates (Yao et al 1980;Yamato Omine Research Group 1981;Taira 1981;Kurimoto 1982Kurimoto , 1986Ishiga 1983;Matsuoka 1984;Otsuka 1985;Isozaki 1986;Takata 1987;Kimura 1988;Taira ei al. 1989;Matsuda & Isozaki 1991;Kimura & Horj 1993).…”

Section: Introductionmentioning

confidence: 99%

Episodic accretion and metamorphism of Jurassic accretionary complex based on biostratigraphy and K‐Ar geochronology in the western part of the Mino‐Tanba Belt, Southwest Japan

Takami

Itaya

1996

Island Arc

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The low grade metamorphic Jurassic accretionary complex in the western part of the Mino-Tanba Belt, Southwest Japan, is a chaotic sedimentary complex which consists of argillaceous matrices with allochthonous blocks of chert, greenstone, siliceous mudstone, terrigenous sandstone and mudstone. The complex is divided into three distinct geologic units, Units I, I1 and 111, with a tectonic boundary (thrust) between them, forming a pile-nappe structure. They have different features for lithologies, fossil age, metamorphic condition and K-Ar age. Microfossil researches revealed that their timings of accretion were in the early Early Jurassic (ca 195 Ma) for Unit 111, in the early Middle Jurassic (ca 175 Ma) for Unit I1 and in the latest Late Jurassic (ca 147 Ma) for Unit I. On the other hand, K-Ar age determinations of white mica separated from pelitic rocks of the three units clarified that the subsequent subductionrelated metamorphism was 23 million years after the accretion of each unit. These results strongly suggest that the accretionary and metamorphic process had taken place episodically with an interval of 20 to 28 million years during Mesozoic time in the western part of the Mino-Tanba Belt, Southwest Japan.

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Upper Paleozoic and Mesozoic strata in the northeastern part of the Mino Terrane, Nagano Prefecture, central Japan

Cited by 8 publications

References 0 publications

Stratigraphy and structure of the Jurassic accretionary complex in the Daigo district, northern Ibaraki and eastern Tochigi Prefectures, central Japan

Stratigraphy and structure of the Jurassic accretionary complex in the Daigo district, northern Ibaraki and eastern Tochigi Prefectures, central Japan

Potential contribution of floral thermogenesis to cold adaptation, distribution pattern, and population structure of thermogenic and non/slightly thermogenic Symplocarpus species

Episodic accretion and metamorphism of Jurassic accretionary complex based on biostratigraphy and K‐Ar geochronology in the western part of the Mino‐Tanba Belt, Southwest Japan

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