Lower cretaceous

An exceptionally well-preserved cranium and mandible of a new species of pterodactyloid pterosaur from the Nova Olinda Member of the Crato Formation (Aptian, Early Cretaceious) of the Araripe Basin, northeastern Brazil, is described. The new taxon is characterized by the presence of a caudally directed parietal crest similar to that seen in pteranodontids, but is referred to the Ornithocheiridae of the Ornithocheiroidea. The specimen is referred to a new genus within the Ornithocheiridae, as it lacks the diagnostic rostral crest and instead possesses this parietal crest oriented. A lanceolate leaf with frayed distal end wedged between the mandibular rami suggests the cause of death for the specimen.

The Tabarak Abad Dam on the river Tabarak, a branch of Atrak river, is located about 25 km of northeast of Quchan city in the northeast of Iran. The dam is now under construction and will be completed in 2002. The Tabarak Abad Dam has been designed as an earthfill dam ...

October Field is one of the most prolific offshore oil fields in the Gulf of Suez of Egypt. It consists of a number of marine platforms and produces oil from different reservoirs of different geological ages from the Lower Cretaceous to the Miocene. The aim of this study was to enhance a seismic-log evaluational procedure to evaluate the Miocene-aged Asl and Hawara Formations which encounter the main hydrocarbon and source rock potentials in the area North of October Oil Field. The well logging data, the borehole seismic data, and the velocity surveys are all used in this study. A number of synthetic seismograms are constructed and interpreted together with the deduced seismic impedance and reflection coefficient data for many wells in the study area. In addition, a comprehensive velocity analysis is performed using the seismic times and the computed average and interval velocities. These seismic-derived parameters are primarily used in recognizing and locating precisely the marl and sand sections of Asl Formation which show low to middle amplitudes. Furthermore, a quantitative well logging analysis is carried out over Asl and Hawara Formations to shed light over their hydrocarbon potentiality. Good oil saturation is exhibited by the Asl sand section which reaches to more than 90% in the southern parts of the study area. The petrophysical characters of this sand are very good in terms of good effective porosity (9% to13%), low shale volume (V sh S h > 85%). The sections of the Asl marl and the Hawara shale on the other hand are considered completely wet. An integrated model making use of the seismic- and log-derived properties is applied over the two studied formations for better understanding the reservoir of interest. Many relations are constructed between velocity, seismic impedance, and the rock pore spaces on one hand and between the velocity, lithology, and fluid content on the other hand. This study revealed that the sand section attains very good oil-bearing potentiality in the study area and proved that the application of an integrated model of the log- and seismic-derived properties led to an enhanced evaluation of the Asl and Hawara Formations, good discrimination between their lithological components besides precise differentiation from the overlying Middle to Late Miocene sections. يعد حقل أكتوبر للزيت أحد أهم حقول البترول البحرية Off-shore المنتجة للزيت في خليج السويس بمصر، فهو يتكون من مجموعه من الأرصفة البحريةPlatforms و ينتج من عده خزانات ذات عصور جيولوجية مختلفة تتراوح من الطباشيري السفلي إلي الميوسين. تهدف هذه الدراسة إلي تطبيق نموذج تقييمي يعتمد علي خواص مشتقه من البيانات السيزمية و تسجيلات الآبار و ذلك لتقييم تكويني "عسل" و "هواره" ذا العصر الميوسيني، حيث يحوي هذان التكوينان علي الجهود الهيدروكربونيةHydrocarbon Potentiality و المصدرية الرئيسية للزيت في منطقه شمال حقل أكتوبر. استخدم في هذه الدراسة العديد من تسجيلات الآبار بالإضافة إلي البيانات السيزمية البئرية و بيانات تسجيلات السرعة. كما تم إنشاء و تفسير مجموعه من السيزموجرامات التخليقية Synthetic seismograms مع كل من الممانعة الصوتية و معامل الانعكاس للعديد من الآبار في منطقه الدراسة. بالاضافه إلي هذا تم عمل تحليل كمي للسرعة باستخدام الزمن السيزمي و السرعات المتوسطة و الفترية المقاسة. هذا وقد استخدمت المعاملات المشتقة من البيانات السيزمية بصفه أساسيه و بدقه في تعيين و تحديد نطاقات المارل و الحجر الرملي لتكوين "عسل" ذات السعه القليلة إلي متوسطة Low to middle amplitude . بالاضافه إلي ذلك تم عمل تحليل كميQuantitative analysis متكامل لتكويني "عسل" و "هواره" باستخدام تسجيلات الآبار و ذلك لإلقاء الضوء علي الجهد الهيدروكربونية لكل منهما. وقد أظهر التحليل الكمي احتواء تكوين "عسل علي تشبعات جيده من الهيدروكربونات تصل إلي أكثر من 90%. كما أوضح أن الخواص البتروفيزيقية لهذا الخزان جيده جده و خاصة في الأجزاء الجنوبية من منطقه الدراسة حيث تتراوح المسامية الفعالةEffective porosity ما بين 9% و 13% و التشبع بالزيت إلي أكثر من 85%، في حين يتضاءل حجم الطفلةShale volume إلي اقل من 5%. و من ناحية أخري اعتبرت صخور الطفل و المارل الخاصة بتكوين "هواره" و الجزء العلوي من تكوين "عسل" نطاقات مشبعه كاملا بالماء Wet zones. تم تطبيق نموذج متكاملIntegrated model يجمع ما بين الخواص السيزمية و البتروفيزيقية و ذلك لفهم طبيعة و خواص التكوينين قيد الدراسة بصوره أفضل. و في هذا الصدد تم إنشاء العديد من العلاقات بين السرعة و الممانعة السيزمية و المسامية الصخرية من ناحية، و بين السرعة والمكونات الصخرية و المحتوي من السوائل من جهة أخري. بصفه عامة أكدت هذه الدراسة علي الخواص الهيدروكربونية المميزه لنطاق الحجر الرملي الخاص بتكوين "عسل" و خاصة في الأجزاء الجنوبية من منطقه الدراسة، كما أثبتت أن تطبيق النموذج المتكامل الذي يجمع ما بين الخواص السيزمية والاخري البتروفيزيقية المشتقة من تسجيلات الآبار قد أدي إلي تحسين تقييم التكوينات المدروسة بدرجه كبيره، فضلا عن تحديد مكوناتهما الصخرية بصوره أوضح، بالاضافه إلي فصلهم الدقيق عن رواسب الميوسين التي تعلوهم.

Quartz-diorite, diorite and granodiorite of Archaic ages are the most common rock types in the Swaziland Middleveld. The composition of the regolith cover is dominated by soil-saprolite complexes. The genetic and mineralogical gradient within the soil-saprolite complexes ...

The 265m thick outcrop shows a deltaic depositional sedimentary system. It shows one major shallowing upward cycle that include 8 facies within 6 smaller shallowing upward cycles. These facies are shale at the lower part of the sequence, medium to coarse sandstone at the upper part of the sequence, however; it shows soft sediment deformation and cross bedded interbedded sandstone -shale in the middle part of the sequence. Also, in the middle part sandstones increase in thickness and amount upward. The six shallowing upward cycles has been delaminated based on the presence of mud cracks, Hummock cross bedding, mud clasts, Skolithos and upward dominance of thick medium to coarse sandstones as signs of shallowing upward within this generally shaly-sand sequence. 
This deltaic sequence has been divided into three parts. The prodelta, lower delta front and upper delta front. The prodelta includes the shale facies and the well bedded yellow fine Sand-Shale facies as distal and proximal facies respectively. The lower delta front includes the Soft sediment deformation yellow fine Sand-Shale facies and the Hummocky cross-bedded yellow fine Sand-Shale facies as distal lower delta front, moreover; both the Soft Sediment Deformation- Cross bedded f-m Sand-Shale facies and the Skolithos f-m Sand-Shale facies interpreted as the proximal part of the lower delta front .  The upper delta front is made up of both the Sahley yellow f-m Sandstone facies and the White m-c Sandstone as upper delta front.

Deformation of the Circum-Rhodope Belt Mesozoic (Middle Triassic to earliest Lower Cretaceous) low-grade schists underneath an arc-related ophiolitic magmatic suite and associated sedimentary successions in the eastern Rhodope-Thrace region occurred as a two-episode tectonic process: (i) Late Jurassic deformation of arc to margin units resulting from the eastern Rhodope-Evros arc–Rhodope terrane continental margin collision and accretion to that margin, and

U-Pb ages of detrital zircon (DZ) grains from Lower Cretaceous foreland basin quartzite conglomerate clasts and sandstones—and from potential sources of quartzite clasts and sandstones—record unroofing of the Sevier fold-thrust belt of Utah and the Mogollon Highlands of Arizona.  The oldest Cretaceous deposits in Utah, the Buckhorn Conglomerate (Berremian-Aptian) of the Cedar Mountain Formation, contain sandstone and quartzite clasts with DZ age spectra statistically indistinguishable to Mississippian-Jurassic sandstones on the Colorado Plateau and in Sevier thrust sheets.  Medial Albian Cedar Mountain Formation conglomerates on the western San Rafael Swell (Short Canyon Conglomerate) and basal Cedar Mountain conglomerates on the Wasatch Plateau in central Utah and the Markagunt Plateau in southwest Utah contain quartzite clasts derived from the Ordovician-Devonian interval in the thrust belt. Middle Albian-lower Cenomanian San Pitch and Sanpete Formations of the lower Indianola Group and upper Dakota Sandstone in central Utah were supplied with Cambrian-Precambrian quartzite clasts, thus recording full incision into approximately 16,000 m of allochthonous strata in the central Utah thrust belt by mid Albian.  These three geochronological provenance intervals define three inverted chronofacies in Lower Cretaceous and basal Upper Cretaceous synorogenic deposits, thus recording a complete unroofing sequence of allochthonous strata in the central Utah thrust belt. 
The Buckhorn Conglomerate on the San Rafael Swell and the Poison Strip Sandstone in eastern Utah do not share a common provenance.  The Poison Strip contains significant proportions of Cordilleran arc derived grains that are also commonly found in the lower Burro Canyon Formation to the southeast, whereas in the Buckhorn Conglomerate they are rare.  Whether this phenomenon is due to temporal or sediment dispersal differences are unclear, it may signal the onset of longitudinal trunk river development subsequent to Buckhorn deposition and coeval with orogenesis.  An additional source of Mesozoic volcanic arc DZ grains might include recycling from tephras within Mesozoic strata from local and southern sources in the Mogollon Highlands.

Reptilian ichnofossils are documented from three levels within the coastal lagoonal Vectis Formation (Wealden Group, Lower Cretaceous) of the Wessex Sub-basin, southern England (coastal exposures of the Isle of Wight). Footprints attributable toIguanodonoccur in arenaceous, strongly trampled, marginal lagoonal deposits at the base of the formation, indicating relatively intense ornithopod activity. These were rapidly buried by influxes of terrestrial and lagoonal sediment. Poorly-preserved footcasts within the upper part of the Barnes High Sandstone Member are tentatively interpreted as undertracks. In the stratigraphically higher Shepherd's Chine Member, footcasts of a small to medium-sized theropod and a small ornithopod originally constituted two or more trackways and are preserved beneath a distinctive, laterally persistent bioclastic limestone bed, characterised by hypichnialDiplocraterion. These suggest relatively low rates of dinosaurian activity on a low salinity, periodically wetted mudflat. Trackway preservation in this case is due to storm-induced shoreward water movements which generated influxes of distinctive bioclastic lithologies from marginal and offshore lagoonal settings. The rapidly-deposited footprint-fills occasionally contain fully articulated shallow burrowing bivalves.