نتایج جستجو برای: jurassic
تعداد نتایج: 4540 فیلتر نتایج به سال:
Early Jurassic fossil plants from sedimentary rocks of Tabbowa, Sri Lanka show a variety of evidence for plant-insect interactions indicative of a terrestrial habitat prevailed in the Gondwanaland. The observed interactions are skelitonizing, blotch and galls, ovipositions or coprolites, leaf mines and leaf chewing. These traces indicate that insects had associated the plants for various purpos...
Two new fossil species, Archaeohelorus polyneurus sp. n. and A. tensus sp. n., assigned to the genus Archaeohelorus Shih, Feng & Ren, 2011 of Heloridae (Hymenoptera), are reported from the late Middle Jurassic, Jiulongshan Formation of Inner Mongolia, China. Based on the well-preserved forewings and hind wings of these specimens, the diagnosis of the Archaeohelorus is emended: forewing 2cu-a in...
AB STRACT: Glauconite and Ca phosphate peloids occur in Jurassic and Cretaceous bioclastic carbonate rocks from pelagic swell sequences of the Algayat-Crevillente Unit (Subbetic Zone). The size and morphology of the peloids are controlled by the bioclasts. The glauconite in both stratigraphic positions is K rich (>0.69 atoms p.f.u.) and shows well-defined 10 AÊ lattice fringes. Poorly crystalli...
The Eskay Creek gold-silver mine, located in northwest British Columbia, is an unusually high-grade ore deposit. The mining industry continues to spend more than $2 million each year on exploration for similar deposits in the area. The geologic setting at the minesite is well studied, but large tracts in north-central British Columbia require more detailed surveys to determine if favourable sit...
The Eskay Creek gold-silver mine, located in northwest British Columbia, is the highest-grade precious-metal volcanogenic massive sulphide deposit in the world. The mining industry continues to spend more than $2 million each year on exploration for similar deposits in the area. The geologic setting at the minesite is well studied, but large tracts in north-central British Columbia require more...
There is increasing evidence that early mammals evolved rapidly into a range of body forms and habitats, right under the noses of the dinosaurs.
a micropaleontological study has been carried out on the samples collected from the sarv abad section, the oldest and only known jurassic sedimentary rocks cropping out in the moghan area. studied sequence consists of carbonates bounded at both base and top by clastic deposits. studied carbonate deposits provide an assemblage of benthic foraminifera as well as calcareous algae. the stratigraphi...
سازند سورمه _ژوراسیک زیرین –بالایی ) کهن ترین عضو گروه خامی (ژوراسیک زیرین –کرتاسه زیرین) است که در نواحی محدودی از زاگرس مرکزی به ویژه فارس داخلی رخنمون دارد. تاکنون هیچگونه مطالعه ای در مورد رخساره ها و چینه نگاری سکانسی این سازند در برش های سطحی انجام نشده است. بنابراین از مهمترین اهداف این مطالعه می توان به بررسی های دقیق صحرایی و آزمایشگاهی برای تعیین رخساره ها، محیط های رسوبی و چینه نگاری...
three granitoid bodies, shirkuh batholith, kaffe abad and ader bolandan are exposed in nw yazd, cutting across the naiband formation (upper triassic), and overlain by cretaceous formations. shirkuh batholith is most likely of jurassic age. it seems to be the first and the most significant episode of magmatism in studied area which occurred in middle jurassic (late cimmerian) time. on the other ...
middle jurassic fluvio-deltaic and turbiditic mudstones of the kashafrud formation, are important hydrocarbon sources in the gas-rich kopet-dagh basin, northeast iran. clay mineral assemblages are important for interpretation of sediment provenance and for understanding burial diagenetic cementation in sandstones. the clay mineral assemblages in mudrocks in two areas, saleh-abad and senjedak, w...
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