Hvítserkur

Hvítserkur (shine, a yanki kuma) wani tulin basalt ne mai tsayin mita 15 tare da gabas ga gabar tekun Vatnsnes, a arewa maso yammacin Iceland. 

Dutsen yana da ramuka biyu a tushe, wanda ke ba shi kamannin dragon wanda ke shan giya. An ƙarfafa tushe na tarin tare da kankare don kare tushe daga teku.

 Labarun gargajiya da yawon shakatawa 
Al’adar yankin ta nuna cewa Hvítserkur ita ce gawawwakin ’ yan bindigar da suka yi ƙoƙarin lalata gidan sufi da ke Þingeyrar da ke kusa da fitowar rana kuma aka mai da shi dutse. A tsakiyar karni na 20, manoma sun damu da cewa "troll" da ke cikin teku zai iya rushe gininsa da kankare, alamar da aka haifa a matsayin kulawa mai mahimmanci kamar na al'ada. 

A yau Hvítserkur yana jan hankalin ɗimbin baƙi, amma rashin alamun hanyoyi ya haifar da tattake wuraren da ake tsugunar da tsuntsayen da ke kusa da kuma hatimi a kan ɓangarorin da ke kusa da su. Wannan ya haifar da muhawara tsakanin masu mallakar filaye, hukumomin gida da masu kiyayewa kan yadda za a daidaita damar shiga kyauta, kare lafiyar baƙo da kare namun daji—batun da ya ƙara matsawa kan matsayin dutsen a yawon buɗe ido na Iceland. 

 Geology 
Hvítserkur ignimbrite wani dutse ne mai launin launi mai haske a Hvítserkur wanda ya zama ɗaya daga cikin manyan zanen gadon wuta a arewa maso gabashin Iceland. Wannan welded tuff yana nuna siffa mai launin ruwan hoda zuwa launin ruwan hoda kuma hadadden cibiyar sadarwa ta dikes basaltic ta ratsa ta. A cikin fallasa da yawa, ignimbrite an lullube shi ta hanyar hyaloclastites da matashin kai-lava breccias, yana nuna cewa bayan fashewar siliki mai fashewa wani tabki mara zurfi ya wanzu a cikin caldera, wanda a cikinsa ya ci gaba da aman wuta.

An sanya Hvítserkur ignimbrite a farkon Miocene (kimanin shekaru miliyan 13-12 da suka wuce, ko Ma) tare da yankin Borgarfjörður Eystri – Loðmundarfjörður rift zone, jerin tsaunuka na tsakiya da suka lalace yanzu an binne su a ƙarƙashin ƙasan basaltic plateau lavas. Kwanan radiyo na 12.5 ± 0.6 da 13.1 ± 0.2 Ma daga rukunin gidaje da ke kusa da su sun daidaita shekarun sa, wanda ya sa ya zama ɗayan tsoffin samfuran silicic da aka kiyaye su a Iceland. Ci gaba da karatun ilimin halittar ɗan adam da isotopic na nufin fayyace yadda ake samar da irin waɗannan magmas masu girma da kuma adana su a cikin wani saitin tectonic na basaltic. 

 Tsarin Caldera da juyin halitta bayan fashewa 
Ƙarƙashin Hvítserkur ignimbrite ya ta'allaka ne da tsarin rugujewar salon kofa mai aunawa kusan 7.5 × 4.5 km a cikin shirin gani. Ma'auni na filin basalt kewaye da ke gudana - yana nutsewa zuwa tsakiyar caldera - tare da kauri mai ƙonewa har zuwa 410 m akan bangon arewa, 277 m zuwa yamma da 180 m zuwa kudu, ya bayyana wani faffadan bakin ciki mai siffar kwano wanda ya cika da wannan fashewar fashewar guda daya. 

Da zarar ignimbrite ya taru, Caldera ya shirya wani tafki mai zurfi wanda har zuwa 70. m na sandstones, siltstones da laka da aka tattara. Wadannan magudanan ruwa sukan nuna ƴan ƴaƴan tatsuniyoyi da busassun faɗuwa, kuma ana saman su da kusan 5. m-kaurin ash-flow Layer-shaida cewa matakin ruwa yana faɗuwa lokaci zuwa lokaci, yana fallasa kwandon ruwa tare da barin sabbin fashewar zubar da toka mai zafi da toka a cikin tafkin. 

Bayan tarwatsewar, yawancin olivine -basalt dikes da sills sun kutsa cikin gadaje na ignimbrite da tafkin; da yawa daga cikin waɗannan kutse sun ciyar da hyaloclastite da matashin kai-lava breccias waɗanda ke rikodin ci gaba, volcanism na ƙasa. Babban koli na Hvítserkur ya kasance a ƙarshe ta hanyar kwararar basalt na suberial, wanda ke nuna komawa ga ficewar mafic . 

Karamin tsaunin Hvítafjall da ke tasowa daga bene na caldera ya ƙunshi rhyolite breccias da aka canza sosai kuma ana fassara shi azaman intra-caldera lava dome ko filogi, yana rikodin sake dawowar magmatic a ƙarshen mataki. Sake ginawa mai girma uku na saman da tushe na ignimbrite yana nuna ainihin ƙarar nau'in pyroclastic na kusan kilomita 4 3 kafin ɓarna daga sassan na sama. 

 Manazarta