YuRA

YuRA, davrai (sistemai) yura, dar tarikhi geologii Zamin davrai duyumi erai mezozoyro guyand, ki 190—195 mln sol muqaddam ogoz yofta 55—58 mln sol davom kardaast. Nomi davra az k-hoi Yura, ki dar Fransiya va Shveysariya voqeand, girifta shudaast. Istilohi «Yu.»-ro s. 1829 geologi fransavi A. Bronyar avvalin bor istifoda burd. Davrai Yu. ba zaminhoi avval, miyona, onro va (sistemaash tabaqai jinshoi kuhii Yu.) ba qismhoi poyon, miyona, bolo taqsim meshavad.

Dar avval va okhirhoi davrai Yu. harakathoi purshiddati tektoniki ba amal omadand. In harakatho makhsusan dar nohiyahoi geosinklinalii atrofi uq. Orom purzurtar budand va in boisi dar garbi Amerikai Shimoli va Janubi, dar sharqi Osiyo va baze joyhoi mintaqai geosinklinalii Bahrimiyonazamin paydo shudani kuhhoi chindor gardid. Dar jarayoni kuhpaydoshavi boshad, magmatizm avj girift. Dar platformaho goh transgressiya va goho regressiyai bahrho ba amal meomad. Dar davrai Yu. materiki Gondvana ba qismho judo shuda, havzai uq-hoi Atlantik va Hind ba vujud meomadand. Dar mintaqai chokhoi kaloni qishri Zamin (Afrikai Sharqi, Amerikai Janubi va dig. joyho) vulqonho otashfshoni mekardand.

Olami organikii Yu. ba olami organikii davrai trias monandi dosht. Dar khushkihoi davrai Yu. hamon rastanihoi luchtukhmi davrai trias, yane ginkgoho, bennetitho, sagovnikho, munmunaho (plaunho), suzanbargho, sarkhasho, chilbandho va g. meruidand. Dar davomi davra yagog guruhi kaloni nabotot na barham khurdaastu na paydo shudaast. Faqat jinsu namudi luchtukhmho khele tagyir yoftaand. Dar khushkihoi Yu. khazandahoi azimjussai alafkhur (diplodok, stegozavr, brontozavr) va khazandahoi darranda (seratozavr, allozavr), inchunin kaltakaloshoi parron — pretozavrho, tirkhurhoi mayda zindagi mekardand. Avvalin parranda — arkheopteriks va shapalakho dar hamin davra paydo shudand. Olami hayvonoti bahrho asosan az narmbadanho — sarpoyho (ammonitho, belemnitho), narmbadanhoi dupalla va ishkampoyho, inchunin marjonho, suzanpustho, bandpoyho, forsminiferaho, mohihoi ustukhondor va g. iborat budand. Baze khazandaho — ikhtinazavrho, pleziozavrho dar bahrho mezistand.

Tahnishasthoi davrai Yu. dar hamai kontinentho va hatto dar qari uqyonus mavjudand. Tarkib va sharoiti paydoishi onho gunogunand. Tahnishasti platformaho asosan kontinentiyu bahri va geosinklinalho bahri va vulqonogeni meboshand. Sharoiti iqlimii yurai avval, alalkhusus yurai miyona, baroi angishthosilshavi va okhirhoi Yu. boshad, baroi namakhosilshavi musoid bud. Tahnishasthoi davrai Yu. dar SSSR, makhsusan dar hamvorihoi Evropai Sharqi, Sibiri Garbi, dar Qrim, Kavkaz, Osiyoi Miyona, Zabaykaliya va Sharqi Dur bisyorand. Dar Tojikistoi on ho dar domanai shimolii q-kuhi Turkiston (koni angishti Shurob), dar kuhistoni Zarafshonu Hisor (vodii q-hoi Zarafshon, Fonu Yagnob, khamihoi Kishtudu Zavron, Mogiyonu Farob, Ziddi, nishebihoi janubii q-kuhi Hisor), depressiyai Tojikiston va az hama ziyodtar dar Darvozu Pomir vujud dorand. Ii tahnishastho az konglomerat, peg, gil, varaqsang, ohaksang, mergel, jinshoi vulqoni, qabathoi angisht, namaksang va g. iboratand, ki dar sharoiti kontinenti, bahri va laguni paydo shudaand.

Gafsii tabaqai jinshoi Yu. dar Tojikistoni Markazi va Jan. Garbi dahho, sadho m va dar Pomir ba yakchand km merasad. Tamomi konhoi angisht, konhoi namaksangi Khojamumin, Khojasartez va g., inchunin baze konhoi neftu gazi respublika dar davrai Yu. ba vujud omadaand.

U. Olimov.