Geology na yankin Capitol Reef

Ilimin ilimin ƙasa na yankin Capitol Reef ya gabatar da rikodin mafi yawan shekarun Mesozoic a wani yanki na Arewacin Amurka a ciki da kewayen Capitol Reif National Park, a kan Colorado Plateau a kudu maso gabashin Utah.

Kusan ƙafa 10,000 (3,000 m) na sassan sedimentary suna samuwa a yankin Capitol Reef, wanda ke wakiltar kusan shekaru miliyan 200 na tarihin ilimin ƙasa na yankin kudu maso tsakiya na jihar Utah ta Amurka. Wadannan duwatsu suna da shekaru daga Permian (shekaru da shekaru miliyan 270) zuwa Cretaceous (shekara da shekaru miliyan 80).  Dutsen dutse a yankin yana nuna yanayin yanayi na dā kamar yadda ya bambanta kamar koguna da maras kyau (Chinle Formation), hamada kamar Sahara (Navajo Sandstone), da teku mai zurfi (Mancos Shale).  

An fara amfani da turɓaya na farko da aka sani a yankin yayin da teku mai zurfi ya mamaye ƙasar a cikin Permian. Da farko an ajiye sandstone amma dutse mai laushi ya biyo baya yayin da teku ta zurfafa. Bayan da teku ta koma baya a cikin Triassic" id="mwMQ" rel="mw:WikiLink" title="Triassic">Triassic, koguna sun ajiye laka kafin a ɗaga yankin kuma ya sha wahala. Daga baya aka kara tarin da aka biyo bayan katako, yashi, laka da toka mai rushewa da iska. Tsakanin zuwa Late Triassic lokacin ya ga karuwar bushewa, a lokacin da aka shimfiɗa dutse mai yawa tare da wasu ajiya daga raƙuman ruwa masu saurin motsi. Yayin da wani teku ya fara dawowa, ya mamaye yankin lokaci-lokaci kuma ya bar ajiyar evaporite. Tsibirin shinge, sand sand sand da kuma daga baya, tidal flats, sun ba da gudummawar yashi don sandstone, sannan kuma da dutse don conglomerate, da laka don shale. Tekun ya koma baya, ya bar rafi, tabkuna da filayen maras kyau don zama wurin hutawa ga turɓaya. Wani teku, Western Interior Seaway, ya dawo a cikin Cretaceous kuma ya bar karin sandstone da shale kawai don ɓacewa a farkon Cenozoic.

Daga shekaru 70 zuwa 50 da suka gabata Orogeny na Laramide, babban taron gine-ginen dutse a yammacin Arewacin Amurka, ya haifar da Dutsen Rocky zuwa gabas. Wataƙila tashin hankali ya yi aiki a kan Kuskuren da aka binne don samar da Waterpocket Fold na yankin. Ƙarin haɓaka na baya-bayan nan na dukan Colorado Plateau da kuma lalacewar da ta haifar sun fallasa wannan ninka a farfajiya kawai a cikin shekaru miliyan 15 zuwa 20 da suka gabata. Shekaru na kankara a cikin Pleistocene sun kara yawan ruwan sama da rushewa. Yankunan da suka fashe na saman Waterpocket Fold sun sha wahala musamman kuma an fallasa fold din kanta kuma an rarraba shi.

 Kashi na farko na laka 
Wasu mahimman ra'ayoyi: Halitta ita ce ƙungiyar da aka ƙayyade kuma an bayyana ta ƙasa tare da halaye na musamman. Wadannan halaye an halicce su ne a lokacin da ba a katse su ba kuma sun fito ne daga takamaiman yanayin da aka kafa shi. Wani memba ƙaramin yanki ne a cikin tsari kuma gado wani yanki ne na musamman na memba. Ƙungiyoyin sune tsarin da ke da alaƙa da hanyoyi masu mahimmanci kamar, alal misali, duk ana ajiye su a lokacin bushewar da ta ɗauki miliyoyin shekaru ko kuma sakamakon teku da ke mamaye wannan yanki a cikin miliyoyin shekaru.

Nau'o'in rashin daidaituwa sune gibin a cikin rikodin ilimin ƙasa. Irin wannan gibin na iya zama saboda rashin saukowa na dogon lokaci ko kuma saboda lalacewar da ta biyo baya wanda ke cire rukunin dutse da aka ajiye a baya. An ba da umarnin sassan da ke biyowa daga tsofaffi zuwa ƙananan rukunin dutse don ƙirƙirar tarihin abubuwan da suka faru. Wannan shine akasin tsari wanda mutum zai gani a cikin ainihin ɓangaren giciye na turɓaya saboda ana sanya sabbin rukunin dutse a saman tsofaffi bisa ga dokar superposition.

 Tsarin Cutler da Kaibab (Permian) 
A farkon lokacin Permian, Utah ta kasance a kan wani shelf na nahiyar wanda wani lokaci-lokaci aka rufe shi da wani hannu mai zurfi na Panthalassa Ocean .  Wannan ɓangaren Laurasia ya kasance a kan iyakar nahiyar da ba ta bambanta da gabar yammacin Afirka ta yanzu ba. Sakamakon tsari suna daga cikin kimanin shekaru 290 zuwa 250 na Cutler Formation  (wanda ake kira rukuni a cikin gida)  Utah ta kusan kasance a kan paleoequator yayin da aka ajiye membobin na farko na Cutler formation amma ya yi ƙaura kusan zuwa 10 ° arewacin latitude kusan shekaru miliyan 275 da suka gabata. Cutler ya rubuta sedimentation a wannan lokacin kuma ya ƙunshi mambobi huɗu (mafi ƙanƙanta zuwa mafi tsufa):

 White Rim Sandstone, (mai tsayayya da Caprock) 
 Organ Rock Shale (ya ɓace a cikin gida),
 Cedar Mesa Sandstone, da kuma
 Elephant Canyon (an binne shi a cikin gida).

Sai kawai mambobi biyu na sandstone na Cutler Formation, Cedar Mesa da White Rim, an fallasa su a cikin wurin shakatawa amma ba za a iya rarrabe su da sauƙi daga juna ba kuma saboda haka galibi ana bi da su a matsayin ɗayan stratigraphic guda ɗaya a can. White Rim da Cedar Mesa sun hada da burbushin yashi mai laushi wanda mai yiwuwa an ajiye shi a cikin yanayin bakin teku wanda ke cike da ruwan teku a lokaci-lokaci. Yashi a cikin waɗannan tsari an ɗan tsara su ta girman, an ƙyalle su sosai (an sa su ta hanyar abrasion), kuma suna daga ƙanƙanta zuwa matsakaici.

Kyakkyawan fitowar ƙafa 800 (240 m) mai kauri na Cedar Mesa da ƙafa 420 (128 m) mai zurfi White Rim ana iya samun su a kasan Sulphur Creek da kuma a kasan Circle Cliffs a waje da iyakar yammacin wurin shakatawa. A wasu yankuna Organ Rock Shale yana tsakanin Cedar Mesa da White Rim amma yana fitowa daga gabashin wurin shakatawa. Dukkanin Elephant Canyon da aka binne a cikin gida da Organ Rock da suka ɓace an fallasa su a kusa da Canyonlands National Park 60 miles (100 km) gabas (dubban ilimin ƙasa na yankin Canyonlands).      

Daga baya a lokacin Permian, Tekun Kaibab ya mamaye ƙasar kuma ya shimfiɗa wani limey ooze wanda daga baya ya zama mai laushi har zuwa 200 feet (60 m) mai kauri Kaibab Limestone.Morris et al., 2003, page 90, "Kaibab Limestone" Wannan shi ne irin wannan launin toka zuwa fari wanda ke kewaye da Grand Canyon zuwa kudu maso yamma (duba Geology of the Grand Canyon area). Ƙananan sassan Kaibab an haɗa su da yashi da yashi kafin babban bangarensa, dutse, ya zama dolomite mai arziki ta hanyar shiga Magnesium. Halitta ta ƙunshi burbushin invertebrates ciki har da brachiopods, bryozoans, crinoids, gastropods, da pelecypods. Za'a iya ganin ɓarkewar dutsen Kaibab a cikin Capitol Reef ne kawai a cikin zurfin canyons da ke cikin yammacin ɓangaren wurin shakatawa. Komawar Tekun Kaibab ta Tsakiyar Permian ya fallasa asalin teku ga rushewa, wanda ya haifar da tashoshin zurfi na 100 feet (30 m) da kuma ƙirƙirar rata a cikin rikodin ilimin ƙasa da ake kira rashin daidaituwa.Morris et al., 2003, page 90, "Kaibab Limestone"    

 Tsarin Moenkopi (Triassic) 
Yanayin yanayi na cikin gida sun fi rigar kuma sun fi zafi a farkon Triassic fiye da yadda suke a baya. A cikin yankin Capitol Reef sakamakon Moenkopi Formation ya kasu kashi huɗu (daga babba zuwa ƙarami): 

 Black Dragon memba
 Sinbad Limestone memba,
 memba na Torrey, da kuma
 memba na Moody Canyon.

Bayanan da suka bambanta da Moenkopi mafi girma suna tare da ƙananan gangaren dutsen da ke fuskantar yammacin Waterpocket Fold. Hawan da kuma raguwar ɓangaren Moenkopi sannan ya haifar da kusan shekaru miliyan 6 wanda ya kasance a duk tsakiyar Triassic.
50 zuwa 110 feet (15 zuwa 34 m) mai kauri Black Dragon ya ƙunshi jan conglomerate, sandstone, da siltstone waɗanda mai yiwuwa an ajiye su a kan wani fili na bakin teku wanda ya biyo bayan Ruwa mai laushi. Chert clasts daga karkashin Kaibab Limestone wani bangare ne na conglomerates a tushe na memba yayin da alamun ripple da mudcracks suka zama ruwan dare a saman sassanta. Har ila yau, ya zama ruwan dare a saman sassan memba shine ƙananan ƙwayoyin carbonate tare da wasu burbushin halittu.  

Daga baya a farkon Triassic, an kwantar da burbushin burbushin halittu masu wadata zuwa laka mai laushi tare da ƙananan yashi da yashi a matsayin ɗan gajeren hannun teku da ya rufe yankin. Wannan ya haifar da 70 zuwa 140 feet (21 zuwa 43 m) mai kauri mai launin rawaya na Sinbad Limestone memba na Moenkopi. Wasu daga cikin burbushin da aka samo a cikin wannan Layer sun hada da nau'in brachiopod Lingula da nau'ikan ammonite Meekoceras .   

Wani nau'in ruwa ya koma yankin a takaice bayan teku ta koma baya. Wannan ya haifar da 250 zuwa 320 feet (76 zuwa 98 m) mai kauri mai launin ruwan kasa zuwa launin cakulan siltstone da kuma sandstone mai kyau na Moenkopi's Torrey Member. Wasu daga cikin gadaje masu kyau suna nuna alamun ripple da kuma lakacracks yayin da sandstone yana da kwance da ƙananan kusurwa. Ana samun ƙananan hanyoyi zuwa manyan burbushin burbushin halittu daga amphibians da Dabbobi masu rarrafe a cikin wannan Layer da kuma nau'ikan halite.  

Mafi ƙanƙanta a cikin Moenkopi shine 320 zuwa 430 feet (98 zuwa 130 m) mai kauri Moody Canyon Member. Moody Canyon an raba shi zuwa raka'a biyu:   

 Ƙananan gangara mai kafa 200 zuwa 300 feet (60 zuwa 90 m) mai kauri na jan-launin siltstone da  
 dutse mai tsawo mai kafa 120 zuwa 130 feet (37 zuwa 40 m) mai kauri na jan-orange siltstone.  

Kimanin kashi 30 zuwa 40% na dutse a cikin naúrar na sama yana da layi yayin da naúrar ba ta da tsari zuwa layi. Ana samun kyawawan bayyanar ɓangaren sama na ripple-laminated a ƙananan ɓangaren Haikali na Masar.

 Tsarin Chinle (Triassic) 
Wani rikitarwa, mai saurin gudu kuma mai yiwuwa tsarin rafi ya rufe mafi yawan kudancin Utah a cikin Late Triassic. Ana samun mambobi daban-daban na Chinle Formation a yawancin Colorado Plateaus. Logs, yashi, laka da iska- jigilar toka na dutsen wuta daga fashewar da ke nesa sun haɗu da rafi yayin da suka yi ƙaura a kan wani kwandon da ke raguwa don samar da Chinle. Gishiri na Uranium da aka tara a cikin wannan tsari a cikin adadi mai yawa na tattalin arziki kuma an kafa itace mai tsayi (mai yiwuwa an taimaka wa petrification ta kasancewar toka na dutsen wuta).  Membobin Chinle da aka wakilta a yankin Capitol Reef sune (daga tsofaffi zuwa ƙarami): 

 Shinarump memba,
 Mai kula da Butte memba,
 Wani memba na gandun daji, da kuma
 Owl Rock memba.

Tare suna samar da tuddai da tsaunuka masu launin ruwan kasa da orange waɗanda ke sama da fararen dutse a wasu lokuta tare da fuskar yammacin Waterpocket Fold.

An ajiye gadaje masu tsattsauran ramuka a cikin manyan tashoshi da suka rushe cikin Moenkopi, wanda ya haifar da 0 zuwa 90 na gida. kafa (0 zuwa 27 m) Fari mai kauri zuwa rawaya mai launin toka mai launin ruwan toka mai samar da Shinarump Memba na Tsarin Chinle.  An yi Shinarump da ƙananan kusurwa zuwa babban kusurwar giciye kuma mai jujjuya lafiya zuwa dutsen yashi mai ɗorewa wanda aka haɗa tare da conglomerate . Ana samun kyawawan wurare na Shinarump kusa da wurin shakatawa na yamma ƙofar da ke ɗaukar siffofi kamar Haikali na Masar da Dutsen Chimney yayin da duk alamun wannan memba ba su zuwa gabas. Membobin da ke sama da Shinarump sun kasance sun fi kyau saboda saurin gudu na rafukan da ke ajiye su. 

 Uplift da abubuwan da suka faru na Cenozoic 

 Ruwa mai laushi, Tafkin Uinta da dutsen wuta 
Orogeny na Laramide ya tarwatsa yankin daga kimanin shekaru miliyan 70 zuwa miliyan 50 da suka gabata kuma a cikin tsari ya haifar da Dutsen Rocky. Yawancin monoclines (wani nau'i mai laushi a cikin dutse) an kafa su ne ta hanyar karfi mai zurfi na Laramide. Ɗaya daga cikin waɗannan monoclines, wanda ake kira Waterpocket Fold, shine babban fasalin yanayin wurin shakatawa. Tsawon kilomita 100 (kilomita 160) yana da layi na arewa maso kudu tare da gefen gabas mai tsayi. An ɗaga yadudduka na dutse a gefen yammacin Waterpocket Fold fiye da ƙafa 7,000 (2,100 m) sama da yadudduka a gabas. Don haka ana fallasa tsofaffin duwatsu a yammacin ɓangaren da ƙananan duwatsu a gabashin ɓangaren. Wataƙila an halicci wannan ƙuƙwalwar ne saboda motsi tare da Kuskuren da ke cikin duwatsun Precambrian da aka ɓoye a ƙasa da duk wani tsari da aka fallasa. Ƙananan girgizar ƙasa da ke ƙasa a cikin 1979 na iya kasancewa daga irin wannan kuskuren.     

Zamani tare da kafa Waterpocket Fold shine ci gaban wani kwandon intermontane (tsakanin duwatsu) a yankin. Tafkin Uinta ya cika wannan kwandon da ruwan rafi da aka samo daga arewa da kudu. Wannan babban tafkin ya wanzu daga kimanin shekaru miliyan 58 har zuwa shekaru miliyan 35 da suka gabata kuma yana da alhakin ƙirƙirar Flagstaff Limestone da Green River Formation, wanda a cikin gida ya kai kauri na kusan 200 feet (60 m). A wasu wurare wadannan tsari suna da kauri sama da 9,000 feet (2,740 m).  Flagstaff fararen launi ne, burbushin burbushin da ke kunshe da dutse mai laushi, tufa da conglomerate wanda ke lalacewa cikin gefuna da gangara.    

Ƙarfin da ya haifar da orogeny na Laramide ya biyo bayan wasu ƙananan shimfiɗa yayin da aka kafa sabon daidaituwa. Wannan ya haifar da rauni a cikin ɓawon burodi wanda ya ba da damar Magma ya shiga cikin farfajiyar don ƙirƙirar hadadden dutsen wuta a yammacin yankin kimanin shekaru 25 zuwa 20 da suka gabata. A cikin ninka, magma ya shiga ta hanyar da kuma tsakanin tsari kimanin shekaru miliyan 4.6 zuwa 3.7 da suka gabata don ƙirƙirar dikes da sills. Ƙananan raƙuman ruwa sun fashe ta hanyar fissures a farfajiyar kuma aikin igneous ya ci gaba da raguwa daga baya. Rushewar da ta biyo baya ta fi so ta cire dutse mai laushi wanda da farko ya binne dicks, sills, da kuma dutsen dutse, sau da yawa yana barin su tsaye a cikin taimako. Ana iya ganin misalai a Kudancin Desert da Cathedral Valley a arewacin ƙarshen fold.

 Rugujewar ƙasa 
Shekaru goma zuwa goma sha biyar da suka gabata duk yankin ya tashi da ƙafafu dubbai (fiye da kilomita) ta hanyar kirkirar Colorado Plateaus. A wannan lokacin tashin hankali ya fi dacewa, ya bar tsarin gaba ɗaya na tsarin da ya fi dacewa. Yawancin rushewar da ta zana yanayin yau ya faru ne bayan da aka ɗaga Colorado Plateau tare da yawancin manyan cututtukan da suka faru tsakanin shekaru 1 da 6 da suka gabata. Ko da a cikin wannan yanayin hamada, ruwa shine wakilin rushewa wanda ke da alhakin zane-zane na wuri mai faɗi. Rashin nauyi, a cikin nau'in dutse ko dutse, yana taka muhimmiyar rawa wajen tsara layin dutse. Iska ƙaramar wakili ce ta rushewa a nan.

An sake tsara tsarin magudanar ruwa a yankin kuma an kara shi yayin da aka ɗaga Waterpocket Fold. Manyan koguna, kamar Kogin Fremont, sun fi ragewa da ci gaba da tashi ta hanyar saukar da ruwa cikin Waterpocket Fold da sauri. Sauran raƙuman ruwa, kamar Sand Creek, sun canza hanyarsu ta hanyar gudana a layi daya da kuma yankewa cikin ƙananan tsari. Duk da haka wasu koguna sun yi ƙoƙari su ci gaba da haɓaka ta hanyar sassaka koguna kawai don daga baya su canza hanya, suna barin koguna a zahiri da tsawo da bushe. An cire jimlar ƙafa 7,000 (2,100 m) na Mesozoic da Cenozoic da aka rufe ta hanyar rushewa a yankin.  
Yanayi mafi sanyi da sanyi sun samo asali a lokacin zamanin Pleistocene kuma sun dawo ta hanyar akalla abubuwa biyu na neoglacial (Ƙananan shekarun kankara) a zamanin yanzu, Holocene .  Koguna da rafi daban-daban a yankin sun cika da karuwar ruwan sama da kuma ruwa mai narkewa daga tsaunuka masu kankara a kan tsaunukan Henry zuwa gabas da Aquarius Plateau zuwa yammacin wurin shakatawa. ambaliyar ruwa, lalacewar tsaunuka, ƙanƙara, da rushewa ƙasa duk sun ba da gudummawa ga saurin lalacewa. Glaciers sun kwashe Dutsen baki mai shekaru 20 zuwa 30 daga saman Dutsen Boulder da Dutsen Thousand Lake waɗanda daga baya aka ajiye su a kan wurin shakatawa ta hanyar raƙuman ruwa masu narkewa daga kankara, duwatsu da ambaliyar ruwa.

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