{"id":27795,"date":"2018-07-31T06:00:31","date_gmt":"2018-07-31T03:00:31","guid":{"rendered":"https:\/\/bilimvegelecek.com.tr\/?p=27795"},"modified":"2018-11-18T14:12:03","modified_gmt":"2018-11-18T11:12:03","slug":"dunyamizin-sekli-ve-ic-yapisi-nasildir","status":"publish","type":"post","link":"https:\/\/bilimvegelecek.com.tr\/index.php\/2018\/07\/31\/dunyamizin-sekli-ve-ic-yapisi-nasildir","title":{"rendered":"D\u00fcnyam\u0131z\u0131n \u015fekli ve i\u00e7 yap\u0131s\u0131 nas\u0131ld\u0131r?"},"content":{"rendered":"

\u015eu g\u00fcnlerde en pop\u00fcler bilimsel konular\u0131ndan biri ya\u015fanabilecek yeni bir gezegen, bir D\u00fcnya 2.0 ke\u015ffetmek hakk\u0131nda. Neredeyse her ay bilim insanlar\u0131n\u0131n \u201cd\u00fcnyaya \u00e7ok benzer bir gezegen\u201d ke\u015ffetti\u011fini okuyoruz haber sitelerinde. \u0130svi\u00e7reli bilim insanlar\u0131n\u0131n ya\u015flanmay\u0131 geciktiren form\u00fcl\u00fc bulmas\u0131 gibi\u2026<\/p>\n

D\u00fcnyan\u0131n kaynaklar\u0131n\u0131 h\u0131zla ve a\u00e7g\u00f6zl\u00fc bir \u015fekilde t\u00fcketti\u011fimiz g\u00fcn\u00fcm\u00fczde yeni d\u00fcnya aray\u0131\u015flar\u0131n\u0131n bilimsel ara\u015ft\u0131rmalara, hatta bilimkurgu filmlere vs. ilham vermesi elbette beklenen bir durum. Peki tam olarak nas\u0131l bir yer ar\u0131yoruz?<\/p>\n

Bu sorunun yan\u0131t\u0131, \u00fczerinde ya\u015fad\u0131\u011f\u0131m\u0131z gezegen hakk\u0131nda baz\u0131 sorular\u0131 da i\u00e7eriyor. D\u00fcnyam\u0131z\u0131n olu\u015fumu, \u015fekli ve yap\u0131s\u0131 hakk\u0131nda baz\u0131 sorularla ba\u015flayal\u0131m. D\u00fcnyam\u0131z\u0131n nas\u0131l bir yap\u0131s\u0131 var? Haluk Eyido\u011fan, 50 Soruda Deprem<\/em><\/a> adl\u0131 kitab\u0131nda (1) bu sorular\u0131 \u015f\u00f6yle yan\u0131tl\u0131yor:<\/p>\n

\u201cD\u00fcnyam\u0131z\u0131n \u015fekli ve i\u00e7 yap\u0131s\u0131 nas\u0131ld\u0131r?\u201d<\/strong><\/p>\n

\u201cJeolojik ve jeofizik ara\u015ft\u0131rmalar\u0131n \u00f6nemli bir b\u00f6l\u00fcm\u00fc, d\u00fcnyan\u0131n bug\u00fcnk\u00fc fiziksel ve kimyasal yap\u0131s\u0131n\u0131 belirlemeye ve elde edilen bulgular\u0131 kullanarak d\u00fcnyan\u0131n olu\u015fum tarihini ve s\u00fcrecini a\u00e7\u0131klamaya y\u00f6nelik \u00e7al\u0131\u015fmalard\u0131r. Yer\u00e7ekimi (gravite), yer manyeti\u011fi, depremlerin ve n\u00fckleer patlatmalar\u0131n \u00fcretti\u011fi sismik dalgalar gibi baz\u0131 jeofizik ara\u015ft\u0131rma ara\u00e7lar\u0131 kullan\u0131larak yerin fiziksel yap\u0131s\u0131 incelenmi\u015f ve \u00f6nemli bilgilere ula\u015f\u0131lm\u0131\u015ft\u0131r. Geli\u015fen \u00f6l\u00e7me ve de\u011ferlendirme teknikleri ile d\u00fcnyam\u0131z\u0131n daha ayr\u0131nt\u0131l\u0131 fiziksel, yap\u0131sal ve mineral \u00f6zelliklerinin ara\u015ft\u0131r\u0131lmas\u0131 \u00e7al\u0131\u015fmalar\u0131 s\u00fcrd\u00fcr\u00fclmektedir.<\/p>\n

\u201cYerk\u00fcrenin yar\u0131\u00e7ap\u0131 ortalama 6371 km\u2019dir. Yerk\u00fcre, olu\u015fumu s\u0131ras\u0131nda ortaya \u00e7\u0131kan al\u00e7alt\u0131 ve y\u00fckseltiler ve kendi ekseni etraf\u0131nda d\u00f6nerken yapt\u0131\u011f\u0131 eksantrik (yalpalama) hareketleri nedeniyle ekvatorlar\u0131 \u015fi\u015fkin, kutuplar\u0131 bas\u0131k, pek d\u00fczg\u00fcn olmayan bir g\u00f6r\u00fcn\u00fcme sahiptir. Ekvator b\u00f6lgesinde yar\u0131\u00e7ap\u0131 43 km daha fazlad\u0131r. En y\u00fcksek yeri denizden 8848 m y\u00fckseklikle Himalaya Da\u011f Serisi i\u00e7erisindeki Everest Da\u011f\u0131, en derin yeri ise, okyanusta deniz d\u00fczeyinden 10.924 m derinlikle Mariana \u00c7ukuru\u2019dur.<\/p>\n

\"\"
\u015eekil 1.<\/strong> Yerk\u00fcre kesitinde yerin jeofiziksel \u00f6zellikleri. Yerin d\u0131\u015f\u0131n\u0131 kaplayan k\u0131r\u0131lgan ve en so\u011fuk olan yerkabu\u011fu, yerin yar\u0131\u00e7ap\u0131n\u0131n b\u00fcy\u00fckl\u00fc\u011f\u00fcne oranla \u00e7ok incedir.(2) Litosfer i\u00e7in ta\u015fyuvar, astenosfer i\u00e7in enezyuvar s\u00f6zc\u00fcklerinin de kullan\u0131lmas\u0131 \u00f6nerilmektedir.<\/figcaption><\/figure>\n

\u201cD\u00fcnyam\u0131z yery\u00fcz\u00fcnden i\u00e7e do\u011fru yerkabu\u011fu, manto ve \u00e7ekirdek olarak adland\u0131r\u0131lan \u00fc\u00e7 ana katmandan olu\u015fmu\u015ftur. (\u015eekil 1) Manto, \u00fcst ve alt manto olarak iki b\u00f6l\u00fcme ayr\u0131l\u0131rken, \u00e7ekirdek de d\u0131\u015f ve i\u00e7 \u00e7ekirdek olarak alt katmanlara ayr\u0131lmaktad\u0131r.<\/p>\n

\u201cYerkabu\u011fu yer hacminin y\u00fczde 1\u2019ini, a\u011f\u0131rl\u0131\u011f\u0131n\u0131n ise y\u00fczde 2,5\u2019unu olu\u015fturur. T\u00fcm manto ise yer hacminin y\u00fczde 84\u2019\u00fcn\u00fc, a\u011f\u0131rl\u0131\u011f\u0131n\u0131n ise y\u00fczde 67\u2019sini kapsar. \u00c7ekirdek yer hacminin y\u00fczde 15\u2019ini olu\u015ftururken, t\u00fcm a\u011f\u0131rl\u0131\u011f\u0131n y\u00fczde 32\u2019sine sahiptir.(3)<\/p>\n

\u201cYerin y\u00fczeyini kaplayan ve s\u0131cakl\u0131\u011f\u0131 di\u011fer alt katmanlara g\u00f6re en d\u00fc\u015f\u00fck olan yerkabu\u011fu, karalarda ortalama 25\u201170 km kal\u0131nl\u0131ktayken, okyanuslar\u0131n alt\u0131nda daha ince olmakta ve kal\u0131nl\u0131\u011f\u0131 5\u20118 km aras\u0131nda de\u011fi\u015fmektedir. (\u015eekil 4) K\u0131tasal yerkabu\u011fu \u00fcstten alta do\u011fru tortul, granit ve bazalt tabakalardan olu\u015fmaktad\u0131r. Okyanusal kabuk ise tortul ve bazalt tabakalardan olu\u015fmu\u015ftur. T\u00fcm bu kabuk tabakas\u0131, kendisi gibi kat\u0131 olan ve daha \u00e7ok manto kaya\u00e7lar\u0131n\u0131n (magmatik k\u00f6kenli kaya\u00e7lar\u0131n*) bask\u0131n oldu\u011fu kat\u0131 nitelikli litosfer adl\u0131 bir katman\u0131n \u00fcst\u00fcne yerle\u015fmi\u015ftir. Yerkabu\u011funun litosfer i\u00e7indeki s\u0131n\u0131r\u0131na Mohorovicic s\u0131n\u0131r\u0131 denir. Litosferin kal\u0131nl\u0131\u011f\u0131 ortalama 70\u2011100 km aras\u0131ndad\u0131r. Litosferin taban s\u0131n\u0131r\u0131nda s\u0131cakl\u0131k 1300 derece santigradd\u0131r.<\/p>\n

\u201cLitosferin alt\u0131nda ise \u00fcst mantonun daha yumu\u015fak (ak\u0131c\u0131) b\u00f6lgesi olan ve astenosfer olarak adland\u0131r\u0131lan b\u00f6l\u00fcm yer al\u0131r. Astenosferin alt\u0131nda mezosfer olarak adland\u0131r\u0131lan \u00fcst manto malzemesi oldu\u011fu \u00f6nerilmi\u015ftir ve fiziksel ve mineral \u00f6zellikleri \u00e7ok iyi bilinmemektedir. Mezosferin litosferden daha kolay \u015fekil de\u011fi\u015ftiren, ancak astenosferden daha az \u015fekil de\u011fi\u015ftirilebilen bir yap\u0131da oldu\u011fu d\u00fc\u015f\u00fcn\u00fclmektedir.(4)<\/p>\n

\"\"
\u015eekil 2.<\/strong> D\u00fcnyam\u0131z\u0131n d\u0131\u015f y\u00fczeyinden derinliklere do\u011fru kabuk, astenosfer ve \u00fcst manto katmanlar\u0131n\u0131n yerle\u015fimi.(2)<\/figcaption><\/figure>\n

\u201cSon yap\u0131lan baz\u0131 izotop analizleri, yerin olu\u015fumunun G\u00fcne\u015f Sistemi\u2019nin olu\u015fumundan sonra 30 milyon y\u0131l i\u00e7erisinde tamamland\u0131\u011f\u0131n\u0131 g\u00f6stermektedir. Bu bulgudan hareketle, yerin manto ve \u00e7ekirde\u011finin olu\u015fumunun ortalama 10 milyon y\u0131l s\u00fcrd\u00fc\u011f\u00fc anla\u015f\u0131lmaktad\u0131r.<\/p>\n

\u201cYerk\u00fcrenin kimyasal ve mineralojik yap\u0131s\u0131n\u0131 olu\u015fturan ana maddeler ana katmanlar\u0131na g\u00f6re \u015f\u00f6yledir:<\/p>\n

\u201cKabuk:<\/strong> Yerkabu\u011fu kimyasal ve mineralojik bak\u0131mdan iki ana kaya\u00e7 grubu taraf\u0131ndan olu\u015fturulur. Granit, kumta\u015f\u0131 ve kire\u00e7ta\u015f\u0131 gibi al\u00fcminyumoksit ve silisyumoksit\u00e7e zengin kaya\u00e7lar birinci grubu, demiroksit ve magnezyumoksit\u00e7e zengin bazalt cinsinden kaya\u00e7lar da ikinci grubu olu\u015fturur.(3) Karasal nitelikli yerkabu\u011fu i\u00e7inde her iki kaya\u00e7 grubu da yer al\u0131rken, okyanuslar\u0131n alt\u0131ndaki kabukta ise yaln\u0131zca ikinci grup kaya\u00e7lar bask\u0131nd\u0131r. Bu nedenle g\u00fcn\u00fcm\u00fcz yerbilimlerinde yerkabu\u011fu okyanusal ve k\u0131tasal olmak \u00fczere ikiye ayr\u0131lmaktad\u0131r.<\/p>\n

\u201cManto:<\/strong> Alt ve \u00fcst mantonun \u00f6nemli oranda demir, magnezyum, silikon ve oksijenden olu\u015ftu\u011funa inan\u0131lmakta, ancak kimyasal yap\u0131s\u0131 ayr\u0131nt\u0131l\u0131 olarak bilinmemektedir. Alt ve \u00fcst manto aras\u0131ndaki s\u0131n\u0131r\u0131n ge\u00e7i\u015fli oldu\u011fu anla\u015f\u0131lm\u0131\u015ft\u0131r.<\/p>\n

\u201cD\u0131\u015f \u00e7ekirdek:<\/strong> Yerin d\u0131\u015f \u00e7ekirde\u011finin s\u0131v\u0131 nitelikli oldu\u011fu belirtilmektedir.(5) Bu g\u00f6r\u00fc\u015f\u00fc destekleyen g\u00f6zlem sismik dalgalardan biri olan S dalgas\u0131n\u0131n (makaslama dalgas\u0131) d\u0131\u015f \u00e7ekirdekten ge\u00e7ememesidir. D\u0131\u015f \u00e7ekirde\u011fin y\u00fczde 8\u201120 aras\u0131nda ala\u015f\u0131ml\u0131 oldu\u011fu, erimi\u015f demirden olu\u015ftu\u011fu \u00f6ne s\u00fcr\u00fclmektedir.<\/p>\n

\u201c\u0130\u00e7 \u00e7ekirdek:<\/strong> Yerin i\u00e7 \u00e7ekirde\u011fi kat\u0131 olup, bile\u015fiminin y\u00fczde 80\u201185 oran\u0131nda demir i\u00e7erdi\u011fi belirtilmektedir. Bu bulgu deprem ve n\u00fckleer patlatma sonucu yer i\u00e7inde ilerleyen sismik dalgalardan, meteoritlerdeki demir bile\u015fiklerinden ve G\u00fcne\u015f ve y\u0131ld\u0131zlardaki demir oranlar\u0131ndan elde edilmi\u015ftir.\u201d<\/p>\n

D\u00fcnyan\u0131n olu\u015fumu, \u015fekli ve i\u00e7 yap\u0131s\u0131 hakk\u0131nda g\u00fczel bir g\u00f6rselle\u015ftirme i\u00e7in Kurzgesagt\u2019\u0131n \u015fu videosuna g\u00f6z atabilirsiniz.<\/p>\n