Ilimin kasa da halayin kasa na Japan
 Ilimin kasa da halayin kasa na Japan | |
|---|---|
| Bayanai | |
| Ƙaramin ɓangare na | ilmin duwatsu |
| Ƙasa | Japan |
Tsibirin na Japan sune masu manyan motsi a tekuna da yawa da su kafi faruwa sama daruruwan miliyoyin shekaru daga tsakiyar Silurian zuwa Pleistocene, sakamakon subduction na Philippine Sea Plate a ƙarƙashin Farantin Eurasia na nahiyar zuwa kudu, da kuma subduction of the Pacific Plate a karkashin North American Plate zuwa arewa.
Japan da farko an haɗa ta da gabar gabashin nahiyar Eurasia. Farantin Philippine da Pacific sun sauka a ƙarƙashin farantin Asiya zuwa gabas na asthenosphere.[1] Wannan canjin matsin lamba daga asthenosphere da ke turawa baya a kan faranti da aka tattauna ya ja Japan zuwa gabas daga Asiya a cikin aiwatar da tsawo na baya. Wannan ya buɗe Tekun Japan kusan shekaru miliyan 15 da suka gabata.[2] Strait of Tartary da Koriya Strait sun buɗe daga baya.
Japan tana cikin yankin dutsen wuta a kan Pacific Ring of Fire . Sauye-sauye ƙananan girgizar ƙasa da kuma ayyukan dutsen wuta na lokaci-lokaci ana jin su a duk faɗin tsibirin. Girgizar ƙasa mai lalacewa, sau da yawa yana haifar da tsunami, yana faruwa sau da yawa a kowace ƙarni. Manyan girgizar ƙasa na baya-bayan nan sun haɗa da girgizar ƙasar Noto ta 2024, girgizar kasa da tsunami ta Tōhoku ta 2011, girgizar kasar Chūetsu ta 2004, da girgijin ƙasa mai girma na Hanshin na 1995.
Tarihin yanayin ƙasa
[gyara sashe | gyara masomin]Mataki na Orogeny
[gyara sashe | gyara masomin]
Ragewar Rodinia kimanin shekaru miliyan 750 da suka gabata ya haifar da tekun Panthalassa, tare da duwatsun da suka zama Japan a zaune a gefen gabas. A cikin farkon Silurian (shekaru miliyan 450 da suka wuce), an fara rushe faranti na teku, kuma wannan tsari yana ci gaba har zuwa yau, yana samar da orogeny mai nisan kusan kilomita 400 a kan iyaka mai hadewa. Da yawa (9 ko 10) faranti na teku an rushe su gaba ɗaya kuma ragowarsu sun yi bel ɗin metamorphic guda biyu. Mafi na baya-bayan nan da aka yi wa faranti, shi ne na Izanagi Plate shekaru miliyan 95 da suka wuce. A halin yanzu Plate ɗin Tekun Philippine yana ƙarƙashin Plate na Amurian na Nahiyar da kuma Plate ɗin Okinawa zuwa kudu a gudun 4 cm/shekara, yana samar da Tudun Nankai da Ramin Ryukyu. Plate na Pacific yana raguwa a ƙarƙashin Plate Okhotsk zuwa arewa a cikin gudun cm 10 a kowace shekara. Matakan farko na ƙaddamarwa-karɓawa sun sake yin fa'ida a gefen ɓawon nahiya sau da yawa, wanda ya bar yawancin tsibiran Jafanan na zamani waɗanda suka ƙunshi duwatsun da aka kafa a lokacin Permian ko kuma daga baya.
Yanayin tsibirin
[gyara sashe | gyara masomin]Kimanin shekaru miliyan 23 da suka gabata, yammacin Japan yanki ne na bakin teku na nahiyar Eurasia. Gilashin da ke raguwa, kasancewar sun fi zurfi fiye da farantin Eurasian, sun ja sassa na Japan wanda ya zama Yankin Chūgoku na zamani da Kyushu zuwa gabas, suna buɗe Tekun Japan (a lokaci guda tare da Tekun Okhotsk) kusan shekaru miliyan 15-20 da suka gabata, tare da yiwuwar tafkin ruwa mai laushi kafin teku ta shiga.[3] Kimanin shekaru miliyan 16 da suka gabata, a lokacin Miocene, an kafa wani tsibirin da ke haɗe da gabar gabashin nahiyar Eurasia. Kimanin shekaru miliyan 11 kafin yanzu, sassan Japan waɗanda suka zama Tōhoku da Hokkaido na zamani an ɗaga su a hankali daga ƙarƙashin teku, kuma an haɓaka yankunan Yankin Chūbu a hankali daga sarkar tsibirin da ke haɗuwa. Strait of Tartary da Koriya Strait sun buɗe daga baya, kimanin shekaru miliyan 2 da suka gabata. A lokaci guda, mummunan raguwar Fossa Magna graben sun kafa Filin Kantō . [4]
Gabaɗaya, ba a fahimci sauyin yanayin ƙasa na Japan ba. Tsibiran Jafananci an kafa su ne da raka'o'in ilimin ƙasa da yawa a layi daya da gaba. Sassan tsibiran da ke fuskantar faranti na teku yawanci ƙanana ne kuma suna nuna babban kaso na kayayyakin dutsen mai aman wuta, yayin da sassan da ke fuskantar Tekun Japan galibi suna da lahani da naɗe-kaɗe. A arewa maso yammacin Japan, ma'auni mai kauri na Quaternary yana yin ƙayyadaddun tarihin yanayin ƙasa musamman wahalaYanayin yanzu
[gyara sashe | gyara masomin]Bayani na gaba ɗaya
[gyara sashe | gyara masomin].[5]
An raba tsibirin Japan zuwa manyan yankuna uku:
- Northeastern Japan, north of Tanagura fault (which had high volcanic activity 14–17 million years before present[6])
- Idosawa Fault
- Senya Fault
- Hidaka Mountains
- Kitakami Mountains
- Ōu Mountains
- Central Japan, between Tanakura fault and Itoigawa-Shizuoka Tectonic Line.
- Fossa Magna graben
- Tanna Fault
- Bōsō Hill Range
- Southwestern Japan, south of Itoigawa-Shizuoka Tectonic Line. The Southwestern Japan is further subdivided into several metamorphic belts stretched along Japan Median Tectonic Line.[7] The parts of Japan north of Japan Median Tectonic Line ("Inner Zone") contains many granitoid fragments dating from Paleogene to Cretaceous period intruding the older material, while south of the line ("Outer Zone") is mostly accretionary complexes of Jurassic period or younger.
- Urasoko fault
- Fukozu Fault
- Neodani Fault
- Nojima Fault
- Hida orogenic belt (Hida Mountains and Ryōhaku Mountains)
- Sangun orogenic belt
- Maizuru orogenic belt
- Tanba-mino orogenic belt
- Ryoke orogenic belt
- Shimanto orogenic belt
- Sambagawa orogenic belt[8]
- Chichibu orogenic belt[9]
- Sambosan orogenic belt
- Beppu–Shimabara graben
Bincike
[gyara sashe | gyara masomin]Geology na Japan galibi ana sarrafa shi ne ta hanyar Geological Society of Japan , tare da manyan littattafai masu zuwa:
- Jaridar Geological Society of Japan - tun 1893
- Nazarin ilimin ƙasa - tun daga 1968
- Geological Society of Japan News (Japan geological SocietyNews) - tun daga 1998
Hadarin Yanayi
[gyara sashe | gyara masomin]Japan tana cikin yankin dutsen wuta a kan Pacific Ring of Fire . Sauye-sauye ƙananan girgizar ƙasa da kuma ayyukan dutsen wuta na lokaci-lokaci ana jin su a duk faɗin tsibirin. Girgizar ƙasa mai lalacewa, sau da yawa yana haifar da tsunami, yana faruwa sau da yawa a ƙarni. Manyan girgizar ƙasa na baya-bayan nan sun haɗa da girgizar ƙasar Noto ta 2024, girgizar kasa da tsunami ta Tōhoku ta 2011, girgizar kasar Chūetsu ta 2004 da girgijin ƙasa mai girma na Hanshin na 1995.
- ↑ Tatsumi, Yoshiyuki; Otofuji, Yo-Ichiro; Matsuda, Takaaki; Nohda, Susumu (1989-09-10). "Opening of the Sea of Japan back-arc basin by asthenospheric injection". Tectonophysics. 166 (4): 317–329. doi:10.1016/0040-1951(89)90283-7. ISSN 0040-1951.
- ↑ Barnes, Gina L. (2003). "Origins of the Japanese Islands: The New "Big Picture"" (PDF). University of Durham. Archived from the original (PDF) on April 28, 2011. Retrieved August 11, 2009.
- ↑ Barnes, Gina L. (2003). "Origins of the Japanese Islands: The New "Big Picture"" (PDF). University of Durham. Archived from the original (PDF) on April 28, 2011. Retrieved August 11, 2009.
- ↑ "Formation history of the Japanese Islands (4) -- GLGArcs". glgarcs.rgr.jp. Archived from the original on December 1, 2017. Retrieved July 16, 2017.
- ↑ "Geology of Japan｜Geological Survey of Japan, AIST｜産総研地質調査総合センター / Geological Survey of Japan, AIST". gsj.jp. Retrieved July 16, 2017.
- ↑ "Yurie SAWAHATA, Makoto Okada, Jun Hosoi, Kazuo Amano, "Paleomagnetic study of Neogene sediments in strike-slip basins along the Tanagura Fault". confit.atlas.jp. Retrieved July 16, 2017.
- ↑ connelly@geo.arizona.edu. "Southwest Japan". geo.arizona.edu. Archived from the original on October 10, 2017. Retrieved July 16, 2017.
- ↑ "Sanbagawa belt (Sambagawa metamorphic belt), Shikoku Island, Japan". mindat.org. Retrieved July 16, 2017.
- ↑ "Chichibu belt from geo.arizona.edu". geo.arizona.edu. Archived from the original on December 5, 2017. Retrieved July 16, 2017.