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Remane, Jürgen. "Jurassic-Cretaceous boundary." Geobios 27 (December 1994): 773. http://dx.doi.org/10.1016/s0016-6995(94)80246-7.
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Erdenetsogt, Bat-Orshikh. "Preliminary results of petroleum source rock evaluation of Mongolian Mesozoic oil shales." Геологийн асуудлууд 15 (February 23, 2023): 46–57. http://dx.doi.org/10.22353/.v15i01.2272.
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Jurassic and Cretaceous oil shale samples, collected from northern and central Mongolian basins, have been analyzed to determine their petroleum source rock potential. The contents of total organic carbon (TOC) and total sulfur, and source rock screening data were obtained by Rock-Eval pyrolysis. Cretaceous oil shales contain up to 17.4 wt.% TOC and Hydrogen Index (HI) values range from 638-957 mg HC/g TOC. Jurassic oil shale samples have similar TOC contents, ranging from 10.7 to 17.3 wt.%. HI values of Jurassic Tsagaan-Ovoo oil shale vary between 270-313 mg HC/g TOC. Average Tmax values of Cretaceous and Jurassic samples are 4370C and 4230C, respectively. This observed data indicates that both Jurassic and Cretaceous oil shales are excellent source rock. Cretaceous oil shales contain type I kerogen (highly oil prone), while Jurassic Tsagaan-Ovoo oil shale has mixed type II/III kerogen (mixed oil and gas prone). Based on Tmax and Production Index values, both Jurassic and Cretaceous oil shales are immature. Overall, the result of this study contributes organic geochemistry database of Mongolian oil shale and encourages source rock potential of both Jurassic and Cretaceous oil shale.
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Yin, Wei. "Hydrocarbon Geology Characteristics and Oil & Gas Resource Potential in the Afghan-Tajik Basin." Advanced Materials Research 734-737 (August 2013): 366–72. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.366.
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The Afghan-Tajik Basin is an intermontane depression between the mountain ranges of Gissar and Pamirs, and Jurassic system and Tertiary system are rich in large oil & gas resources. In order to assure sustainable supply of oil & gas from Central Asia, we deeply researched hydrocarbon geology characteristics and resource potentials. The basin belongs to paralic sedimentary environment, and develops 3 sedimentary strata: Jurassic, Cretaceous, and Tertiary. Afghan-Tajik Basin develops 3 main source rocks including clastic rocks of Jurassic, carbonate rocks of Cretaceous and mudstone rocks of Eocene. The basin develops 2 plays: Jurassic-Cretaceous play is gas containing one, and Tertiary play is oil containing one. Plaster stone and salt rock of upper Jurassic are regional cap rocks of Jurassic-Cretaceous gas pool, and creaming mudstone and muddy limestone of Cretaceous and Tertiary are regional or partial cap rocks. Migration and accumulation of hydrocarbon occur in the late Cretaceous and early Pliocene epoch. Afghan-Tajik Basin has larger exploration potentials, and residual resources are 2.4¡Á108t. The potential zones are as follows, south part of basin, oil-gas structures of post-salt, reef limestone of pre-salt, and litho-stratigraphic traps.
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Sun, Shou-Liang, Shu-Wang Chen, Zhong-Jie Yang, Tao Zhang, Yong-Fei Li, Ji-Chang Zhu, Huai-Chun Wu, Tian-Tian Wang, Yue-Juan Zheng, and Qiu-Hong Ding. "Age of the Tuchengzi Formation in Western Liaoning Province and the Jurassic–Cretaceous Boundary from the Continuous Core Records of Well YD1, Jinyang Basin." Minerals 12, no. 8 (July 28, 2022): 953. http://dx.doi.org/10.3390/min12080953.
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The Tuchengzi Formation is widely distributed in western Liaoning Province with a clear top and bottom. It is the focal area for the delineation of the terrestrial Jurassic–Cretaceous boundary in China. Based on continuous core samples taken from well YD1, detailed lithostratigraphic sequences and zircon uranium–lead (U-Pb) dating were used to investigate the Tuchengzi Formation. The zircon U-Pb ages of the tuff samples taken from the First and Third Members of the Tuchengzi Formation ranged from 153.8 to 137.16 Ma, indicating that they were formed in the late Middle Jurassic–Early Cretaceous. Dating results from the bottom of the Second Member of the Tuchengzi Formation indicate that the sedimentary time of the stratum is no later than 145.7 ± 2.1 Ma. We concluded that the Jurassic–Cretaceous boundary of the Jinyang Basin in western Liaoning province may be located at the interface at a depth of 464 m in well YD1. This conclusion is consistent with the Jurassic–Cretaceous boundary that has been presumed by other researchers based on paleontological assemblage features found in recent years, and can provide useful geological marker beds for the future study of the terrestrial Jurassic–Cretaceous boundary. In addition, the authors also systematically sorted the potential development areas and layers of the terrestrial Jurassic–Cretaceous boundary line, which may also provide useful geological marker beds for the future study of the terrestrial Jurassic–Cretaceous boundary.
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Mannion, Philip D. "A turiasaurian sauropod dinosaur from the Early Cretaceous Wealden Supergroup of the United Kingdom." PeerJ 7 (January 24, 2019): e6348. http://dx.doi.org/10.7717/peerj.6348.
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The Jurassic/Cretaceous (J/K) boundary, 145 million years ago, has long been recognised as an extinction event or faunal turnover for sauropod dinosaurs, with many ‘basal’ lineages disappearing. However, recently, a number of ‘extinct’ groups have been recognised in the Early Cretaceous, including diplodocids in Gondwana, and non-titanosauriform macronarians in Laurasia. Turiasauria, a clade of non-neosauropod eusauropods, was originally thought to have been restricted to the Late Jurassic of western Europe. However, its distribution has recently been extended to the Late Jurassic of Tanzania (Tendaguria tanzaniensis), as well as to the Early Cretaceous of the USA (Mierasaurus bobyoungi and Moabosaurus utahensis), demonstrating the survival of another ‘basal’ clade across the J/K boundary. Teeth from the Middle Jurassic–Early Cretaceous of western Europe and North Africa have also tentatively been attributed to turiasaurs, whilst recent phylogenetic analyses recovered Late Jurassic taxa from Argentina and China as further members of Turiasauria. Here, an anterior dorsal centrum and neural arch (both NHMUK 1871) from the Early Cretaceous Wealden Supergroup of the UK are described for the first time. NHMUK 1871 shares several synapomorphies with Turiasauria, especially the turiasaurs Moabosaurus and Tendaguria, including: (1) a strongly dorsoventrally compressed centrum; (2) the retention of prominent epipophyses; and (3) an extremely low, non-bifid neural spine. NHMUK 1871 therefore represents the first postcranial evidence for Turiasauria from European deposits of Early Cretaceous age. Although turiasaurs show clear heterodont dentition, only broad, characteristically ‘heart’-shaped teeth can currently be attributed to Turiasauria with confidence. As such, several putative turiasaur occurrences based on isolated teeth from Europe, as well as the Middle Jurassic and Early Cretaceous of Africa, cannot be confidently referred to Turiasauria. Unequivocal evidence for turiasaurs is therefore restricted to the late Middle Jurassic–Early Cretaceous of western Europe, the Late Jurassic of Tanzania, and the late Early Cretaceous of the USA, although remains from elsewhere might ultimately demonstrate that the group had a near-global distribution.
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Bata, Timothy. "Evidences of Widespread Cretaceous Deep Weathering and Its Consequences: A Review." Earth Science Research 5, no. 2 (May 2, 2016): 69. http://dx.doi.org/10.5539/esr.v5n2p69.
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This study highlights the effect of the Cretaceous greenhouse climate on weathering processes. Atmospheric CO2 level was relatively higher in the Cretaceous than it was in both the Jurassic and the Cenozoic. Consequently, temperature and humidity were higher in the Cretaceous than in the Jurassic and the Cenozoic. The interaction among the high levels of atmospheric CO2, extreme global warmth, and humidity in the Cretaceous resulted in widespread deep weathering. Cretaceous palaeo-weathering profiles are observed to occur at higher palaeolatitudes relative to the Jurassic and Cenozoic palaeo-weathering profiles. This implies the upward warming of the Cretaceous palaeolatitude, consistent with palaeotemperature estimates for the Cretaceous. The present thickness of weathering profiles in some selected tropical zones is approximately 200 m. During the greenhouse climatic condition in the Cretaceous, the thickness of weathering profiles at those areas could have been up to 4–5 times the present value. This suggests that many sediments were produced from the Cretaceous weathering events.
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Jacobson, Carl E., César Jacques-Ayala, Andrew P. Barth, Juan Carlos García y Barragán, Jane N. Pedrick, and Joseph L. Wooden. "Protolith age of the Altar and Carnero complexes and latest Cretaceous–Miocene deformation in the Caborca–Altar region of northwestern Sonora, Mexico." Revista Mexicana de Ciencias Geológicas 36, no. 1 (March 27, 2019): 95–109. http://dx.doi.org/10.22201/cgeo.20072902e.2019.1.784.
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In the Caborca–Altar area of northwest Sonora, variably deformed and metamorphosed sedimentary and volcanic rocks crop out in a northwest-southeast–trending belt (El Batamote belt) at least 70 km long. We obtained detrital zircon U-Pb ages from two distinctive components of the belt near Altar, here termed the Altar complex and Carnero complex. Zircon ages for metasandstone and metaconglomerate matrix from the Altar complex indicate a Late Cretaceous maximum age of sedimentation, with at least part of the complex no older than 77.5 ± 2.5 (2σ). Pre-Cretaceous detrital zircons in the complex were derived largely from local sources, including Proterozoic basement, the Neoproterozoic–Cambrian miogeocline and the Jurassic arc. The detrital zircon ages and lithologic character of the Altar complex suggest correlation with the Escalante Formation, the uppermost unit of the Upper Cretaceous El Chanate Group. In contrast, one sample from the Carnero complex yielded a Middle Jurassic maximum depositional age and a detrital zircon age distribution like that of the Jurassic eolianites of the North American Cordillera. The Carnero complex may correlate with the Middle Jurassic Rancho San Martín Formation but could also be a metamorphosed equivalent of the Upper Jurassic Cucurpe Formation, Upper Jurassic to Lower Cretaceous Bisbee Group, or El Chanate Group derived by recycling of Jurassic erg sandstones. The Late Cretaceous age for the Altar complex protolith contradicts models that relate deposition of the entire El Batamote protolith to a basin formed by oblique slip along the Late Jurassic Mojave-Sonora megashear. Instead, the belt is best explained as an assemblage of Middle Jurassic to Upper Cretaceous formations deformed and locally metamorphosed beneath a northeast-directed Laramide thrust complex. Potassium-argon and 40Ar/39Ar ages confirm previous inferences that deformation of El Batamote belt occurred between the Late Cretaceous and late Eocene. A second phase of deformation, involving low-angle normal faults, occurred during and/or after intrusion of the ~22-21 Ma Rancho Herradura granodiorite.
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Egebjerg Mogensen, Tommy, and John A. Korstgård. "Triassic and Jurassic transtension along part of the Sorgenfrei–Tornquist Zone in the Danish Kattegat." Geological Survey of Denmark and Greenland (GEUS) Bulletin 1 (October 28, 2003): 437–58. http://dx.doi.org/10.34194/geusb.v1.4680.
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In the Kattegat area, Denmark, the Sorgenfrei–Tornquist Zone, an old crustal weakness zone, was repeatedly reactivated during Triassic, Jurassic and Early Cretaceous times with dextral transtensional movements along the major boundary faults. These tectonic events were minor compared to the tectonic events of the Late Carboniferous – Early Permian and the Late Cretaceous – Early Tertiary, although a dynamic structural and stratigraphic analysis indicates that the Sorgenfrei–Tornquist Zone was active compared to the surrounding areas. At the end of the Palaeozoic, the area was a peneplain. Regional Triassic subsidence caused onlap towards the north-east, where the youngest Triassic sediments overlie Precambrian crystalline basement. During the Early Triassic, several of the major Early Permian faults were reactivated, probably with dextral strike-slip along the Børglum Fault. Jurassic – Early Cretaceous subsidence was restricted primarily to the area between the two main faults in the Sorgenfrei–Tornquist Zone, the Grenå–Helsingborg Fault and the Børglum Fault. This restriction of basin development indicates a change in the regional stress field at the Triassic–Jurassic transition. Middle Jurassic and Late Jurassic – Early Cretaceous subsidence followed the Early Jurassic pattern with local subsidence in the Sorgenfrei–Tornquist Zone, but now even more restricted to within the zone. The subsidence showed a decrease in the Middle Jurassic, and increased again during Late Jurassic – Early Cretaceous times. Small faults were generated internally in the Sorgenfrei–Tornquist Zone during the Mesozoic with a pattern that indicates a broad transfer of strike-slip/oblique-slip motion from the Grenå–Helsingborg Fault to the Børglum Fault.
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Ellis, G. K., A. Pitchford, and R. H. Bruce. "BARROW ISLAND OIL FIELD." APPEA Journal 39, no. 1 (1999): 158. http://dx.doi.org/10.1071/aj98011.
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The Barrow Island Field in the Barrow Sub-basin of the Carnarvon Basin was discovered in 1964 by West Australian Petroleum Pty Limited. It is the largest oil field in Western Australia. Appraisal drilling has defined in-place oil of 200 GL (1,250 MMBBL) and in-place gas of 16.5 Gm3 (580 BCF) primarily in the Lower Cretaceous Windalia Sand Member of the Muderong Shale and in- place gas of 14.5 Gm3 (515 BCF) in Middle Jurassic Biggada Formation. Additional hydrocarbon reservoirs have been discovered, including oil and gas in the Upper Jurassic Dupuy Formation, the Lower Cretaceous Malouet Formation, Flacourt Formation and Tunney Member, Mardie Greensand Member and M zones of the Muderong Shale and in the Upper Cretaceous Gearle Siltstone. Approximately 850 wells have been drilled to appraise and develop these accumulations, and to provide water source and water injection wells to enhance recovery. Production commenced in December 1966, with the first shipment of oil in April 1967. Although numerous hydrocarbon reservoirs have been developed, 95% of the 44 GL (278 MMBBL) of produced oil has been from the Windalia Sand.Structural development of the Barrow Island anticline occurred initially during the Middle Jurassic and continued intermittently during the Cretaceous and Tertiary. Initial charging of the Dupuy and Malouet formations with oil from the Upper Jurassic Dingo Claystone occurred in the Early Cretaceous prior to the development of the shallower closures. Periodic wrench- related movement on the Barrow Fault during the Early to Late Cretaceous produced closures at the Lower Cretaceous reservoirs and provided a catalyst for oil migration and charging of these closures. Significant amounts of an extremely biodegraded component, and several less biodegraded phases are present in the oil in the Windalia Sand, indicating several phases of oil charging of the Barrow structure from Middle and Upper Jurassic sediments. In the Tertiary, gas sourced from Triassic and Jurassic sediments migrated into the Barrow structure via a dilated Barrow Fault, charged the Middle Jurassic Biggada Formation and displaced some of the oil in the Lower Cretaceous reservoirs.
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Zhimulev, F. I., E. V. Vetrov, I. S. Novikov, G. Van Ranst, S. Nachtergaele, S. A. Dokashenko, and J. De Grave. "Mesozoic Intracontinental Orogeny in the Tectonic History of the Kolyvan’– Tomsk Folded Zone (Southern Siberia): a Synthesis of Geological Data and results of Apatite Fission Track Analysis." Russian Geology and Geophysics 62, no. 9 (September 1, 2021): 1006–20. http://dx.doi.org/10.2113/rgg20204172.
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Abstract —The Kolyvan’–Tomsk folded zone (KTFZ) is a late Permian collisional orogen in the northwestern section of the Central Asian Orogenic Belt. The Mesozoic history of the KTFZ area includes Late Triassic–Early Jurassic and Late Jurassic–Early Cretaceous orogenic events. The earlier event produced narrow deep half-ramp basins filled with Early–Middle Jurassic molasse south of the KTFZ, and the later activity rejuvenated the Tomsk thrust fault, whereby the KTFZ Paleozoic rocks were thrust over the Early–Middle Jurassic basin sediments. The Mesozoic orogenic events induced erosion and the ensuing exposure of granitoids (Barlak complex) that were emplaced in a within-plate context after the Permian collisional orogeny. Both events were most likely associated with ocean closure, i.e., the Paleothetys Ocean in the Late Triassic–Early Jurassic and the Mongol–Okhotsk Ocean in the Late Jurassic–Early Cretaceous. The apatite fission track (AFT) ages of granitoids from the Ob’ complex in the KTFZ range between ~120 and 100 Ma (the Aptian and the Albian). The rocks with Early Cretaceous AFT ages were exhumed as a result of denudation and peneplanation of the Early Cretaceous orogeny, which produced a vast Late Cretaceous–Paleogene planation surface. The tectonic pattern of the two orogenic events, although being different in details, generally inherited the late Paleozoic primary collisional structure of the Kolyvan’–Tomsk zone.
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Shevchuk, Olena, and Kateryna Ivanchenko. "Acritarchs of the Mesozoic of Ukraine." Visnyk of V.N. Karazin Kharkiv National University, series Geology. Geography. Ecology, no. 55 (December 1, 2021): 107–16. http://dx.doi.org/10.26565/2410-7360-2021-55-08.
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Introduction. Acritarchs are one of the orthostratigraphic groups of microfossils that are widely used in Proterozoic and Paleozoic biostratigraphy. In the Mesozoic period there is a decrease in this group, and this is due to certain reasons. Formulation of the problem. Acritarchs are studied by palynologists from samples of Mesozoic sediments in combination with other representatives of organic bone microplankton, primarily with dinocysts. In the practice of Ukrainian micropaleontologists, the role of such a group as acritarchs, which may be unique in paleoecological reconstructions of the environment, is underestimated. History of the study of acritarchs. None of the researchers studied the group of acritarchs in the Mesozoic deposits of Ukraine. In scientific works it was noted only about the presence of these forms in the description of palynological complexes of Jurassic, Cretaceous and other times. Brief description of the group. Acritarchs are unicellular, non-colonial, organic microfossils. Formulation of the purpose of the article. The aim of the study was to focus on such a little-studied group for the Mesozoic as acritars and to prove its role and significance for stratigraphic and paleoecological constructions. Materials and methods. The research material was samples of rocks of the Middle, Upper Jurassic and Cretaceous deposits, selected separately from 93 sections, but from all major tectonic structures of Ukraine: Peninsky zone of the Carpathians, Volyn-Podolsk plate, western and eastern slopes of the Ukrainian Shield, Priazovsky array of the Ukrainian shield, Dnieper-Donetsk basin, Donbas, South Ukrainian monocline (Black Sea basin), Crimea, North-Azov depression and Azov shaft (Ukrainian part of the Sea of Azov). Presentation of the main material of the study. Acritarchs Jurassic and Cretaceous belong to 10 genera, including 11 species. The most common species found in both Jurassic and Cretaceous sediments of Ukraine are acritarchs Micrhystridium fragile and Fromea sp. Jurassic complexes are slightly richer than chalk in terms of percentage and are represented mainly by Micrhystridium spp., Micrhystridium flagile, M. longum, Veryhachium brevitrispinum, Wilsonastrum sp., Baltisphaeridium sp. Cretaceous: Micrhystridium spp., Micrhystridium fragile, M. longum, Baltisphaeridium breviciliatum, B. aff. capillatum, B. annelieae, B. accinctum, Acanthodiacrodium sp., Solisphaeridium inaffectum, Comasphaeridium sp., Comasphaeridium aff. brachyspinosum, Veryhachium spp., Veryhachium singulare, Leiofusa stoumonensis, Fromea sp., Ascostomocystis sp. The article presents photo tables of images of Jurassic and Cretaceous acritarchs. Conclusions. For the first time in Ukraine, acritarchs were found in samples from Jurassic and Cretaceous sediments and attention was focused on such a little-studied group for the Mesozoic. Their certain role and significance for stratigraphic and paleoecological constructions are proved, their species composition and vertical distribution in sections of Mesozoic sediments are studied. The regularities of the distribution of acritarchs in the same age layers are established. Analyzing the Jurassic and Cretaceous microfossils studied from Mesozoic sediments from 93 sections of different regions of Ukraine, we can say that the trend of disappearance of acritarchs during the Mesozoic is weakly observed. Jurassic forms of acritarchs are up to 5% in the complex, Cretaceous - up to 4%. The next stage of work should be the study of acritarch Jurassic and Cretaceous deposits of all regions of Ukraine for the purposes of the overall picture of the reproduction of paleoecological conditions in Ukraine during the Jurassic and Cretaceous period.
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Yousif, Samir, and Ghalib Nouman. "Jurassic Geology of Kuwait." GeoArabia 2, no. 1 (January 1, 1997): 91–110. http://dx.doi.org/10.2113/geoarabia020191.
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ABSTRACT Until the late 1970s only one well penetrated the entire Jurassic section of Kuwait. A few other scattered wells partially penetrated it. During the 1980s an appreciable number of deep wells revealed that the Jurassic sequence is inverted with respect to the Cretaceous sequence and that the main Cretaceous arches were sites of Jurassic sedimentary troughs. This new interpretation marks a revolution in the existing concepts for Jurassic oil exploration in Kuwait. One of the most effective methods for defining of Jurassic structures is the isopach of the Upper Jurassic Gotnia Formation. The main Jurassic reservoirs include the Najmah, Sargelu and Marrat formations which were detected as a result of the exploration activities during the 1980s. Selective stratigraphic and structural cross-sections reveal the stratigraphic relationships of the Jurassic sediments.
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Harland, W. Brian, and Simon R. A. Kelly. "Chapter 19 Jurassic-Cretaceous history." Geological Society, London, Memoirs 17, no. 1 (1997): 363–87. http://dx.doi.org/10.1144/gsl.mem.1997.017.01.19.
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Jurassic-Cretaceous follows Triassic history with minor change. It was an interval dominated by deposition of marine muds, silts and sands, with occasional non-marine environments on advancing deltas (Parker 1967; Harland 1973a; Kelly 1988). Subdued topography contrasted with Triassic and Paleogene terrains. But there was also Late Jurassic and Early Cretaceous intrusion of basic sills and volcanism in eastern Svalbard. Figure 19.1 shows the distribution of Jurassic and Cretaceous deposits in Svalbard.The two periods (208-65 Ma) span 143 million years but the stratal record for this interval totals only 1700 m of which more than half was deposited in Albian time. The Jurassic-Cretaceous rocks of the eastern platform, presently cropping out on some islands, represent a relict of a once continuous sheet of strata, which is still preserved extensively across much of the Barents Shelf.The Triassic-Jurassic boundary is marked by seemingly continuous facies from Rhaetian to Toarcian; but then follows a contrast between the main Spitsbergen Basin (which hardly subsided) and the Eastern Platform. The contrasting areas of east and west Svalbard were divided by the continuing activity along the Billefjorden lineament. To the east, subsidence permitted a complex and variable sequence resulting from deltas from the east (marine and non-marine) through Liassic to mid-Bathonian time. To the west there was little evident subsidence and only condensed deposits of the uppermost Wilhelmoya Formation were washed by shallow seas. This part of the story concluded the history of the Kapp Toscana Group.A Late Bathonian marine transgression transformed east and
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Rahman, Mat Niza Bin Abdul. "Jurassic-Cretaceous Stratigraphy of Malaysia." Open Journal of Geology 09, no. 10 (2019): 668–70. http://dx.doi.org/10.4236/ojg.2019.910070.
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KENT, DENNIS V., and FELIX M. GRADSTEIN. "A Cretaceous and Jurassic geochronology." Geological Society of America Bulletin 96, no. 11 (1985): 1419. http://dx.doi.org/10.1130/0016-7606(1985)96<1419:acajg>2.0.co;2.
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Japsen, Peter, Peter Britze, and Claus Andersen. "Upper Jurassic – Lower Cretaceous of the Danish Central Graben: structural framework and nomenclature." Geological Survey of Denmark and Greenland (GEUS) Bulletin 1 (October 28, 2003): 231–46. http://dx.doi.org/10.34194/geusb.v1.4653.
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The Danish Central Graben is part of the mainly Late Jurassic complex of grabens in the central and southern North Sea which form the Central Graben. The tectonic elements of the Danish Central Graben in the Late Jurassic are outlined and compared to those in the Early Cretaceous based on reduced versions of published maps (1:200 000), compiled on the basis of all 1994 public domain seismic and well data. The Tail End Graben, a half-graben which stretches for about 90 km along the East North Sea High, is the dominant Late Jurassic structural feature. The Rosa Basin (new name) is a narrow, north–south-trending basin extending from the south-western part of the Tail End Graben. The Tail End Graben ceased to exist as a coherent structural element during the Early Cretaceous and developed into three separate depocentres: the Iris and Gulnare Basins to the north and the Roar Basin to the south (new names). The Early Cretaceous saw a shift from subsidence focused along the East North Sea High during the Late Jurassic to a more even distribution of minor basins within the Danish Central Graben. The depth to the top of the Upper Jurassic – lowermost Cretaceous Farsund Formation reaches a maximum of 4800 m in the northern part of the study area, while the depth to the base of the Upper Jurassic reaches 7500 m in the Tail End Graben, where the Upper Jurassic attains a maximum thickness of 3600 m. The Lower Cretaceous Cromer Knoll Group attains a maximum thickness of 1100 m in the Outer Rough Basin.
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Stoica-Negulescu, Elena-Rodica. "DEEP KARST AREAS EVIDENCED BY SEISMIC RESEARCH IN MOESIAN PLATFORM." Romanian Journal of Petroleum & Gas Technology 4 (75), no. 1 (2023): 109–20. http://dx.doi.org/10.51865/jpgt.2023.01.10.
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"Around half of the total carbonate rocks of Romanian territory are Upper Jurassic-Lower Cretaceous age. Most of them are able to develop karst phenomena. In the southern-central part of the Moesian Platform Jurassic-Cretaceous deposits are at 2000-3000 m depth. The existence of the hydrocarbon accumulations in the area was just proved (Talpa, Harlesti, Videle fields). In the calcareous deposits, the seismic profiles and the attributes of seismic traces highlighted some specific geological features: The collapse karst areas, formed in Jurassic-Neocomian deposits. The seismic expression of these areas is one of chaotic reflections zone flanked by converging, strong tilted faults. The paleo-valley systems formed by erosion of the Cretaceous relief, filled with different terms of the Lower Sarmatian (a succession of marls and sands). The reflections configuration is specific to the passing from the valley fill lithology to the Cretaceous calcareous formations of the adjacent areas. The reef build-ups in Upper Jurassic-Lower Cretaceous formations, expressed by chaotic reflection mound zones draped for quasi horizontal superimposed strata. The seismic trace attributes and velocity analyses are important tools in reservoir quality definition, giving information regarding porosity and fluid contents. "
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Zagorovsky, Yuri A. "The North Tambey uplift history study using 3D seismic data." Georesursy 24, no. 2 (September 30, 2022): 69–76. http://dx.doi.org/10.18599/grs.2022.3.5.
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Paper shows the information about the geological and geophysical exploration of Tambeyskoye natural gas field located in the north of the Yamal Peninsula. The problems with mapping of natural gas deposits in Cretaceous and Jurassic formations are described. The results of formation thickness analysis are presented in order to explain the reasons for the unprecedented concentration of separate natural gas accumulations and the heterogeneous saturation of massive reservoirs in Cretaceous formations. The method of paleotectonic analysis is briefly described, the initial data are reported. Structural and isopach maps are presented. Structural elements and their evolution in Jurassic and Cretaceous time are presented. It was concluded that different structural elements of the work area transformed quite independently until the end of Cenomanian. The modern shape of North Tambey uplift was forming during the Neogene to Quarter age. Natural gas bearing reservoirs in Jurassic formation with the overpressure were reported. The young age of the North Tambey uplift, the unprecedented concentration of separate natural gas accumulations, the and the heterogeneous saturation of massive reservoirs in Cretaceous formations, overpressure in Jurassic formation – all these facts show that the Tambeyskoye natural gas field is under active gas accumulation. Hydrocarbon gases coming from deep Jurassic formations and it was not enough time for gas accumulations to be distributed over the reservoirs of Cretaceous.
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Orme, Devon A., and Kathleen D. Surpless. "The birth of a forearc: The basal Great Valley Group, California, USA." Geology 47, no. 8 (June 6, 2019): 757–61. http://dx.doi.org/10.1130/g46283.1.
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AbstractThe Great Valley basin of California (USA) is an archetypal forearc basin, yet the timing, structural style, and location of basin development remain controversial. Eighteen of 20 detrital zircon samples (3711 new U-Pb ages) from basal strata of the Great Valley forearc basin contain Cretaceous grains, with nine samples yielding statistically robust Cretaceous maximum depositional ages (MDAs), two with MDAs that overlap the Jurassic-Cretaceous boundary, suggesting earliest Cretaceous deposition, and nine with Jurassic MDAs consistent with latest Jurassic deposition. In addition, the pre-Mesozoic age populations of our samples are consistent with central North America sources and do not require a southern provenance. We interpret that diachronous initiation of sedimentation reflects the growth of isolated depocenters, consistent with an extensional model for the early stages of forearc basin development.
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Wilson, Frederic H., James G. Smith, and Nora Shew. "Review of radiometric data from the Yukon Crystalline Terrane, Alaska and Yukon Territory." Canadian Journal of Earth Sciences 22, no. 4 (April 1, 1985): 525–37. http://dx.doi.org/10.1139/e85-054.
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The results of more than 20 years of geochronological studies in the Yukon Crystalline Terrane in east-central Alaska and the western Yukon Territory suggest at least six igneous and thermal (metamorphic?) events. Plutonism during Mississippian, Early Jurassic, mid-Cretaceous, Late Cretaceous, and early Tertiary times is indicated. Evidence also indicates that Mississippian, Early Jurassic, late Early Cretaceous, and late Cretaceous thermal (metamorphic?) events have affected parts of the terrane. The western part of the terrane was affected by a significant regional metamorphic event in late Early Cretaceous time, followed by a terrane-wide mid-Cretaceous plutonic event. The pattern of K–Ar ages allows division of the terrane into domains, bounded by northeast-trending lineaments.
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Hancock, J. M., and P. F. Rawson. "Cretaceous." Geological Society, London, Memoirs 13, no. 1 (1992): 131–39. http://dx.doi.org/10.1144/gsl.mem.1992.013.01.13.
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AbstractEarly CretaceousThe Cretaceous Period lasted for about 70 million years. During this time there was a major change in the sedimentary history of the area as tectonism died down and deposition started of an extensive blanket of coccolith ooze: the Chalk. The change took place mainly over a brief interval across the Albian/Cenomanian (Lower/Upper Cretaceous) boundary, at about 95 Ma. Until that time crustal extension along the Arctic-North Atlantic megarifts continued to influence the tectonic evolution of northwest Europe (Ziegler 1982, 1988). This tensional régime caused rifting and block faulting, particularly across the Jurassic-Cretaceous boundary (Late Cimmerian movements) and in the mid Aptian (Austrian phase). During the latter phase, sea-floor spreading commenced in the Biscay and central Rockall Rifts. The northern part of the Rockall Rift began to widen too, possibly by crustal stretching rather than sea-floor spreading (Ziegler 1988, p. 75). During the Albian the regional pattern began to change and by the beginning of the Cenomanian rifting had effectively ceased away from the Rockall/Faeroe area.Most of the Jurassic sedimentary basins continued as depositional areas during the Early Cretaceous, but the more extensive preservation of Lower Cretaceous sediments provides firmer constraints on some of the geographical reconstructions. The marked sea-level fall across the Jurassic-Cretaceous boundary isolated the more southerly basins as areas of non-marine sedimentation, and it was not until the beginning of the Aptian that they became substantially marine.The extent of emergence of highs in the North Sea area is difficult to assess, especially where
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Greig, Charles J. "Jurassic and Cretaceous plutonic and structural styles of the Eagle Plutonic Complex, southwestern British Columbia, and their regional significance." Canadian Journal of Earth Sciences 29, no. 4 (April 1, 1992): 793–811. http://dx.doi.org/10.1139/e92-067.
Full textAbstract:
The Eagle Plutonic Complex is an elongate north-northwest-trending body of deformed Middle to Late Jurassic and middle Cretaceous rocks which underlies the southwestern margin of the Intermontane terrane. New mapping of the complex and its country rocks, in concert with geochronometry, has defined episodes of contractional, ductile deformation in the Middle to Late Jurassic and middle Cretaceous, as well as brittle deformation in Tertiary time. Synkinematic Middle to Late Jurassic Eagle tonalite at the eastern margin of the Eagle Complex intrudes mylonitic Nicola Group rocks and structurally overlies them along a southwest-dipping belt of high strain (Eagle shear zone) with a structural thickness of > 1 km and a strike length of > 100 km. In the central and western Eagle Complex, Eagle tonalite grades into tonalite orthogneiss (Eagle gneiss), and both are crosscut by mid-Cretaceous, muscovite-bearing plutons of the Fallslake Plutonic Suite. Fallslake Suite rocks are themselves ductilely deformed along the Pasayten fault, which bounds the Eagle Complex on the west and was active mainly in the mid-Cretaceous (ductile deformation with sinistral, east-side-up, reverse displacement). The Jurassic and Cretaceous episodes of deformation may reflect the respective initial and final stages of the accretion of the Insular terrane to the North American margin. West of the Pasayten fault, Middle to Late Jurassic and older(?) rocks of the Zoa Complex are structurally overlain, in part, by deformed Middle Eocene and middle Cretaceous sedimentary rocks. In the north, the Middle Eocene rocks are intruded on their west side by the Middle Eocene Needle Peak pluton.
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Fischer, Valentin, Robert M. Appleby, Darren Naish, Jeff Liston, James B. Riding, Stephen Brindley, and Pascal Godefroit. "A basal thunnosaurian from Iraq reveals disparate phylogenetic origins for Cretaceous ichthyosaurs." Biology Letters 9, no. 4 (August 23, 2013): 20130021. http://dx.doi.org/10.1098/rsbl.2013.0021.
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Cretaceous ichthyosaurs have typically been considered a small, homogeneous assemblage sharing a common Late Jurassic ancestor. Their low diversity and disparity have been interpreted as indicative of a decline leading to their Cenomanian extinction. We describe the first post-Triassic ichthyosaur from the Middle East, Malawania anachronus gen. et sp. nov. from the Early Cretaceous of Iraq, and re-evaluate the evolutionary history of parvipelvian ichthyosaurs via phylogenetic and cladogenesis rate analyses. Malawania represents a basal grade in thunnosaurian evolution that arose during a major Late Triassic radiation event and was previously thought to have gone extinct during the Early Jurassic. Its pectoral morphology appears surprisingly archaic, retaining a forefin architecture similar to that of its Early Jurassic relatives. After the initial latest Triassic radiation of early thunnosaurians, two subsequent large radiations produced lineages with Cretaceous representatives, but the radiation events themselves are pre-Cretaceous. Cretaceous ichthyosaurs therefore include distantly related lineages, with contrasting evolutionary histories, and appear more diverse and disparate than previously supposed.
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Jones, Douglas S., and David Nicol. "Origination, survivorship, and extinction of rudist taxa." Journal of Paleontology 60, no. 1 (January 1986): 107–15. http://dx.doi.org/10.1017/s0022336000021557.
Full textAbstract:
Rudists arose in the Late Jurassic and survived for nearly 100 m.y. before becoming extinct at the end of the Cretaceous. Over this interval they diversified gradually during the Late Jurassic and Early Cretaceous, rapidly in the mid-Cretaceous, then more slowly in the Late Cretaceous. Total rates of origination and extinction during the Late Jurassic and Early Cretaceous were uniform and comparable to those reported for other groups. The Late Cretaceous, however, was characterized by high and widely fluctuating total origination and extinction rates. Per taxon rates reveal a similar pattern except for high and variable rates in the Jurassic. The number of genera increased from the Oxfordian to a peak in the Cenomanian, decreased in the Turonian and Coniacian coinciding with a minor mass extinction event, and rose to a zenith in the Maastrichtian. Unlike other groups investigated, the rudists were at their highest level of diversity immediately prior to their disappearance.Rudist genera survived for a mean of 12 m.y., whereas families survived for a mean of 48 m.y. Survivorship curves for generic cohorts, based upon survival of all rudist genera that evolved during each stage, exhibit a concave shape when the effects of mass extinction and variance at low diversities are considered. Causal factors involved in the final disappearance of the rudists remain unclear; however, their tropical provinciality in the Late Cretaceous contributed to their vulnerability to mass extinction.
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Zakharov, Yuri D., Vladimir B. Seltser, Mikheil V. Kakabadze, Olga P. Smyshlyaeva, and Peter P. Safronov. "Oxygen–carbon isotope composition of Middle Jurassic–Cretaceous molluscs from the Saratov–Samara Volga region and main climate trends in the Russian Platform–Caucasus." Geological Society, London, Special Publications 498, no. 1 (October 17, 2019): 101–27. http://dx.doi.org/10.1144/sp498-2018-57.
Full textAbstract:
AbstractOxygen and carbon isotope data from well-preserved mollusc shells and belemnite rostra are presented from the Jurassic (Bathonian, Callovian and Tithonian) and Cretaceous (Aptian, Turonian, Campanian and Maastrichtian) of the Saratov–Samara Volga region, Russia. New data provide information on the resulting trends in palaeoclimate and in palaeoceanography and palaeoecology in the late Mesozoic. Palaeotemperatures calculated from Jurassic–Cretaceous benthic (bivalves and gastropods) and semi-pelagic (ammonites) molluscs are markedly higher than those calculated from pelagic belemnites using oxygen isotopes. This is probably due to various mollusc groups of the Saratov–Samara area inhabiting different depths in the marine basins (e.g. epipelagic v. mesopelagic). Our isotope records, combined with a review of previously published data from shallow-water fossils from the Saratov–Samara area and adjacent regions permits us to infer temperature trends for the epipelagic zone from the Middle Jurassic to Cretaceous in the Russian Platform–Caucasus area. The Jurassic–Cretaceous belemnites from the Russian Platform and the Caucasus have a lower δ13C signature than the contemporaneous brachiopods, bivalves and ammonites.
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Wang, Ping Li, Da Wei Lv, Hai Yan Liu, Xue Zheng, and Yu Lin Lv. "Migration Law of Mesozoic Qaidam Basin Depocenters." Advanced Materials Research 524-527 (May 2012): 63–66. http://dx.doi.org/10.4028/www.scientific.net/amr.524-527.63.
Full textAbstract:
According to stratigraphy and distribution features of the Qaidam Basin, and further the formation and migration of it’s depocenters, it is considered that the Middle-Upper Triassic were mainly sags scattered among the Qilian Mountains, the Alabasitao Mountains and the Kunlun Mountains; the Early Jurassic depocenters were located mainly in Lenghu depression and Yiliping sag at the northwest of the basin; several Middle Jurassic depocenters distributed from the northwest to the southeast of the basin along Sertengshan-Yuqia near front of the Qilian mountains; the Late Jurassic-Cretaceous depocenters moved east and south. The basin had been larger since the Middle Jurassic, and the sedimentary facies changed from semideep-deep lacustrine of the Early-Middle Jurassic to near-source variegated fluvial-lacustrine of the Late Jurassic and brownish red lakeshore of the Early Cretaceous.
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Carman, George J. "Structural Elements of Onshore Kuwait." GeoArabia 1, no. 2 (April 1, 1996): 239–66. http://dx.doi.org/10.2113/geoarabia0102239.
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ABSTRACT Five structural trends are recognized in Kuwait: (1) Three sub-parallel anticlinal trends (005°-015°) occur on the west flank of the Kuwait Arch and trap oil in Lower Cretaceous and Jurassic strata. (2) North-south trending structures, including the Kuwait Arch, are probably founded on basement horsts. These were reactivated from Late Jurassic to post-Turonian time and contain the largest oil pools in Kuwait (e.g. Greater Burgan) in Middle Cretaceous, Lower Cretaceous and Upper Jurassic strata. (3) A northwest trend (320°-340°) in north and west Kuwait reflects the structural grain of the underlying Arabian Shelf and while generally dry in Middle Cretaceous strata has proven oil in Lower Cretaceous and Jurassic strata. (4) East-northeast (030°-050°) anticlines are present mid-flank the Kuwait Arch to the west and north. They contain oil in Jurassic and Lower Cretaceous strata, and Middle Cretaceous strata where north-south trends are overprinted. They may be related to northeast trending shear zones. (5) The Ahmadi Ridge is a rare north-northwest contraction trend probably related to the Zagros orogeny and traps oil where it overprints the Kuwait Arch trend. The apparently simple anticlinal oil field structures are cut by normal faults, which are mapped as radial, with throws up to 50 meters but averaging 15 meters. Structural compartmentalization of reservoirs has not been conclusively identified. The faults are near-vertical and often occur in swarms; the majority deform strata below the Mishrif Unconformity while rare faults reach the surface. Reverse throws are evident on seismic and in one well. Dextral offsets along northwest and northeast trending fault and lineaments indicate strike-slip. Wellbore breakouts, processed borehole imagery data and outcrop joint data define a principal maximum stress field orientation of 040°-050° consistent with regional trends.
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Rogov, M. A., N. G. Zverkov, V. A. Zakharov, and M. S. Arkhangelsky. "Marine reptiles and climates of the Jurassic and Cretaceous of Siberia." Стратиграфия 27, no. 4 (June 16, 2019): 13–39. http://dx.doi.org/10.31857/s0869-592x27413-39.
Full textAbstract:
All available data on the Jurassic and Cretaceous climates of Siberia, based on isotope, palaeontological and lithological markers are summarized. Late Pliensbachian cooling, early Toarcian warming, followed by late Toarcian to Middle Jurassic cooling and long-term Late Jurassic warming are well-recognized. Gradual cooling started since the late Ryazanian and continued during the whole Early Cretaceous except the short early Aptian warming event. At the beginning of the Late Cretaceous climate became warmer with warming peak at the Cenomanian–Turonian transition. During the middle and late Turonian climate became colder. During the Coniacian–Campanian time interval climate became warmer, but at the end of the Campanian new cooling event occurred. New records of marine reptiles from the Toarcian, Kimmeridgian, Volgian and Santonian–Campanian of the north of Eastern Siberia are described. All data concerning marine reptile occurrences in the Jurassic and Cretaceous of Siberia are reviewed; these records (from 51 localities) are mostly located at high palaeolatitudes. The analysis has revealed that most of the localities containing fossil reptile remains were llocated in the Transpolar palaeolatitudes (70°–87°). There are no direct relationship between climate oscillations and distribution of these animals. Taking into account recent data arguing that nearly all groups of the Jurassic and Cretaceous big marine reptiles were able to maintain constant body temperature and also were capable make long-range seasonal migrations, any conclusions concerning usage of these animals as markers of warm climate should be treated with a caution.
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Girard, Vincent, Simona Saint Martin, Eric Buffetaut, Jean-Paul Saint Martin, Didier Néraudeau, Daniel Peyrot, Guido Roghi, Eugenio Ragazzi, and Varavudh Suteethorn. "Thai amber: insights into early diatom history?" BSGF - Earth Sciences Bulletin 191 (2020): 23. http://dx.doi.org/10.1051/bsgf/2020028.
Full textAbstract:
The origin of the diatoms still remains enigmatic. Their fossil record is scarce until the Late Cretaceous and great divergences exist between molecular data and the earliest fossil evidence. While molecular data indicate an origin during the Triassic or Early Jurassic, early fossil evidence is only from the Late Jurassic-Early Cretaceous. The discovery of diatoms in French mid-Cretaceous amber by the end of the 2000s already suggested a potential bias in the diatom fossil record as it made older many diatom lineages, the record of which hitherto began at the end of the Cretaceous. The Jurassic/Early Cretaceous fossil record of diatoms is extremely sparse and any new occurrence is important for retracing the evolutionary, palaeogeographical and palaeoenvironmental history of diatoms. Thai amber has yielded a new diatom specimen that has been attributed to the genus Hemiaulus. Fossil assemblages and sedimentological data indicate that Thai amber and its Hemiaulus specimen are Late Jurassic in age. This discovery represents the oldest hitherto known specimen of Hemiaulus and so extends the fossil record of the bipolar diatoms and of the genus Hemiaulus by several dozens of millions of years and brings closer the fossil evidence and molecular data (that estimated an origin of the bipolar diatoms about 150 Ma ago). It reinforces the hypothesis of a pre-Cretaceous fossil diatom records and also supports an origin of the diatoms in shallow coastal environments.
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JOUAULT, CORENTIN, VALÉRIE NGÔ-MULLER, QINGQING ZHANG, and ANDRÉ NEL. "New empidoid flies (Diptera: Atelestidae; Dolichopodidae) from mid-Cretaceous Burmese amber." Palaeoentomology 3, no. 2 (April 30, 2020): 204–11. http://dx.doi.org/10.11646/palaeoentomology.3.2.10.
Full textAbstract:
Examination of mid-Cretaceous Burmese amber reveals a new species of Atelestidae: Alavesia myanmarensis sp. nov., and the female of the dolichopodid Microphorites pouilloni Ngô-Muller & Nel, 2020. Both are described and illustrated. Alavesia myanmarensis sp. nov. is the first species of Alavesia from the mid-Cretaceous amber of northern Myanmar. The oldest records of this genus of small Diptera are from the Early to Late Cretaceous ambers of Spain, while the Burmese amber was probably produced on an island during the mid-Cretaceous, which had separated from Gondwana during the Jurassic. It suggests a possible Late Jurassic origin of the genus Alavesia.
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Zhang, Lei, Zhi Ping Li, and Guo Ming Liu. "Permeability Curves Characteristic Analysis of L Oilfield." Advanced Materials Research 616-618 (December 2012): 898–901. http://dx.doi.org/10.4028/www.scientific.net/amr.616-618.898.
Full textAbstract:
The L oilfield Cretaceous (M-I-1), Jurassic Department (Ю-0-3) clastic pore types, including primary porosity, secondary porosity and cracks in three categories, their characteristics and the degree of development. Chalk Department of particles holes and grain dissolution porosity, an average of 53.2%, followed by argillaceous porous and contraction joints, while a small number of particles dissolved pore, showing a small amount of paste particles seam and tensile crack; Jurassic inter-granular holes and intra-granular dissolution porosity is developed, accounting for the porosity as high as 95%, while a small amount of argillaceous porous and granulizing hole and a very small amount of mold holes. L Oilfield Cretaceous and Jurassic reservoirs inter-granular pores, inter-granular dissolution pore, pore throat combination M-I-1, mainly to large - in the hole, micro-throat, Ю-0-3 large - in the hole Extra Coarse - rough throat-based thin throat, Ю-0-1, Jurassic sandstone pore structure better than the Cretaceous.
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Michetiuc, Mihai, Camelia Catincuţ, and Ioan Bucur. "An Upper Jurassic-Lower Cretaceous carbonate platform from the Vâlcan Mountains (Southern Carpathians, Romania): paleoenvironmental interpretation." Geologica Carpathica 63, no. 1 (February 1, 2012): 33–48. http://dx.doi.org/10.2478/v10096-012-0003-9.
Full textAbstract:
An Upper Jurassic-Lower Cretaceous carbonate platform from the Vâlcan Mountains (Southern Carpathians, Romania): paleoenvironmental interpretationThe results of a biostratigraphic and sedimentological study of the Upper Jurassic-Lower Cretaceous limestones cropping out in the southern sector of the Vâlcan Mountains in Romania are presented, including the definition of microfacies types, fossil assemblages and environmental interpretation. Six microfacies types (MFT 1-MFT 6) have been identified, each of them pointing to a specific depositional environment. The deposits are characteristic of a shallow carbonate platform. They contain normal marine or restricted marine facies deposited in low or high energy environments from the inner, middle and outer platform. The age attribution of these deposits (Late Jurassic to Berriasian-Valanginian-?Hauterivian, and Barremian) is based on foraminiferal and calcareous algae associations. The micropaleontological assemblage is exceptionally rich in the Vâlcan Mountains and brings new arguments for dating the Upper Jurassic-Lower Cretaceous limestones in this area.
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Kostaki, G., A. Kilias, H. J. Gawlick, and F. Schlagintweit. "?Kimmeridgian-Tithonian shallow- water platform clasts from mass flows on top of the Vardar/Axios ophiolites." Bulletin of the Geological Society of Greece 47, no. 1 (December 21, 2016): 184. http://dx.doi.org/10.12681/bgsg.10923.
Full textAbstract:
The Late Jurassic to Early Cretaceous sedimentary succession of the Neochorouda Unit lies unconformably on top of the Oreokastro ophiolites of the Vardar/Axios “suture zone” in northern Greece. This succession consists of turbidites and mass flows and provides an upper limit for ophiolite emplacement. New biostratigraphic and microfacies analysis from the clasts in the mass flows were carried out for a better understanding of the Late Jurassic to Early Cretaceous geodynamic history. Microfacies and organism content prove the onset of Late Jurassic carbonate platforms on top of a Middle to Late Jurassic nappe stack striking from the Eastern Alps to the Hellenides. Middle to Late Jurassic nappe stacking towards WNW to NW followed late Early to Middle Jurassic intra-oceanic thrusting in the Western Vardar/Axios (= Neotethys) Ocean and subsequent ophiolite obduction onto the Pelagonian Units forming a thin-skinned orogen on the lower plate. After ophiolite emplacement Kimmeridgian- Tithonian carbonate platforms sealed widespread this tectonic event. Tithonian extension due to mountain uplift resulted in partial erosion of these platforms and new extensional basins were formed. Late Tithonian to earliest Cretaceous erosion of the uplifted nappe stack including the obducted ophiolites resulted in sediment supply into the newly formed basins also east of the Pelagonian Units.
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Michelsen, Olaf, Niels Frandsen, Lise Holm, Thorkild Feldthusen Jensen, Jens Jørgen Møller, and Ole Valdemar Vejbæj. "Jurassic - Lower Cretaceous of the Danish Central Trough; - depositional environments, tectonism, and reservoirs." Danmarks Geologiske Undersøgelse Serie A 16 (December 15, 1987): 1–45. http://dx.doi.org/10.34194/seriea.v16.7035.
Full textAbstract:
A revised model for the Jurassic - Early Cretaceous basin development in the Danish Central Trough is described on the basis of new studies of the bio- and lithostratigraphy and sedimentological and seismic data. The trough has been subdivided into a number of areas, each characterized by specific structural evolution. Middle Jurassic fluvio-deltaic and coastal sands follow the mid Cimmerian unconformity and probably cover large parts of the trough. Right-lateral movements, initiated during the Late Jurassic along WNWESE trending faults, caused fault controlled basin subsidence. The Jurassic and early Early Cretaceous sedimentation were dominated and characterized by clay. More than 4000 m of clay were deposited. Organic carbon rich clays were deposited from the Kimmeridgian until the Late Ryazanian, when deposition of organic carbon poor sediments under oxygenated conditions commenced. During the Late Jurassic transgression coastal sands were deposited along tectonically quiet basin margins. Sands deposited from density currents accumulated along tectonically active margins at the Jurassic-Cretaceous transition. More centrally in the basins, more distal turbidite deposits of Late Jurassic age may be present. Early Cretaceous basin expansion caused by elevation of the sea-level led to decreasing siliciclastic deposition rates and hence to more calcareous sediment types. Contemporaneously basin subsidence decreased. At mid Hauterivian time the importance of differential subsidence governed by left-lateral transtensional wrenching along NNW-SSE trending faults decreased. This change was accompanied by a mild inversion controlled by NNW-SSE directed right-lateral transpression, heralding regional subsidence. Following this inversion chalk was deposited in almost the entire trough area. Later, during the Barremian and Aptian anoxia in the basin caused deposition of marls rich in organic carbon, followed by marls deposited under oxygenated conditions during the Albian transgression. The distribution and character of possible reservoir bodies are discussed.
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Webster, Ewan Russell, and David R. M. Pattison. "Spatially overlapping episodes of deformation, metamorphism, and magmatism in the southern Omineca Belt, southeastern British Columbia." Canadian Journal of Earth Sciences 55, no. 1 (January 2018): 84–110. http://dx.doi.org/10.1139/cjes-2017-0036.
Full textAbstract:
The southeastern Omineca Belt of the Canadian Cordillera preserves a record of overlapping Barrovian and Buchan metamorphism spanning 180–50 Ma. This paper documents the timing, character, and spatial relationships that define separate domains of Middle Jurassic, Early Cretaceous, and Late Cretaceous deformation and metamorphism, and the nature of the geological interfaces that exist between them. A domain of Early Jurassic deformation (D1) and regional greenschist-facies metamorphism (M1) is cross-cut by Middle Jurassic (174–161 Ma) intrusions. Associated contact aureoles are divided into lower pressure (cordierite-dominated; ∼2.5–3.3 kbar; 1 kbar = 100 MPa) and higher pressure (staurolite-bearing; 3.5–4.2 kbar) subtypes; contact metamorphic kyanite occurs rarely in some staurolite-bearing aureoles. Jurassic structures are progressively overprinted northwards by Early Cretaceous deformation and metamorphism (D2M2), manifested in a tightening of Jurassic structures, development of more pervasive ductile fabrics, and Barrovian metamorphism. The D2M2 domain is the southerly continuation of the 600 km long Selkirk–Monashee–Cariboo metamorphic belt. Mid-Cretaceous intrusions (118–90 Ma) were emplaced throughout the D2M2 domain, the earliest of which contain D2 fabrics, but cut M2 isograds. The D2M2 domain makes a continuous, southeasterly transition into a domain of Late Cretaceous regional Barrovian metamorphism and deformation (D3M3; 94–76 Ma). The interface between these two domains is obscured by the coaxial nature of the deformation and the apparent continuity of the metamorphic zones, resulting in a complex and cryptic interface. Similarities between the D3M3 domain and the Selkirk Crest of Idaho and Washington suggest that this domain is the northerly continuation of the northward-plunging Priest River Complex.
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Bourli, Nicolina, George Iliopoulos, Penelope Papadopoulou, and Avraam Zelilidis. "Microfacies and Depositional Conditions of Jurassic to Eocene Carbonates: Implication on Ionian Basin Evolution." Geosciences 11, no. 7 (July 9, 2021): 288. http://dx.doi.org/10.3390/geosciences11070288.
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In order to decipher the paleo-depositional environments, during the Late Jurassic to Early Eocene syn-rift stage, at the margins of the Ionian basin, two different areas with exposed long sequences have been selected, Kastos Island (external margin) and Araxos peninsula (internal margin), and were examined by means of microfacies analysis and biostratigraphy. On Kastos Island, based on lithological and sedimentological features, the following depositional environments have been recognized: an open marine/restricted environment prevailed during the Early Jurassic (“Pantokrator” limestones), changing upwards into deep-sea and slope environments during the Late Jurassic and Early Cretaceous (Vigla limestones). The Upper Cretaceous (Senonian limestones) is characterized by a slope environment, whereas during the Paleogene, deep-sea and toe of slope conditions prevailed. In Araxos peninsula, Lower Cretaceous deposits (“Vigla” limestones) were accumulated in a deep-sea environment; Upper Cretaceous ones (Senonian limestones) were deposited in slope or toe of slope conditions. Paleocene limestones correspond to a deep-sea environment. In Araxos peninsula, changes occurred during the Cretaceous, whereas on Kastos Island, they occurred during the Paleocene/Eocene, related to different stages of tectonic activity in the Ionian basin from east to west.
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Prokopiev, Andrei V., Victoria B. Ershova, and Daniel F. Stockli. "Detrital Zircon U-Pb Data for Jurassic–Cretaceous Strata from the South-Eastern Verkhoyansk-Kolyma Orogen—Correlations to Magmatic Arcs of the North-East Asia Active Margin." Minerals 11, no. 3 (March 11, 2021): 291. http://dx.doi.org/10.3390/min11030291.
Full textAbstract:
We performed U-Pb dating of detrital zircons collected from Middle–Upper Jurassic strata of the Sugoi synclinorium and Cretaceous rocks of the Omsukchan (Balygychan-Sugoi) basin, in order to identify their provenance and correlate Jurassic–Cretaceous sedimentation of the south-eastern Verkhoyansk-Kolyma orogenic belt with various magmatic belts of the north-east Asia active margins. In the Middle–Late Jurassic, the Uda-Murgal magmatic arc represented the main source area of clastics, suggesting that the Sugoi basin is a back-arc basin. A major shift in the provenance signature occurred during the Aptian, when granitoids of the Main (Kolyma) batholith belt, along with volcanic rocks of the Uyandina-Yasachnaya and Uda-Murgal arcs, became the main sources of clastics deposited in the Omsukchan basin. In a final Mesozoic provenance shift, granitoids of the Main (Kolyma) batholith belt, along with volcanic and plutonic rocks of the Uyandina-Yasachnaya and Okhotsk-Chukotka arcs, became the dominant sources for clastics in the Omsukchan basin in the latest Cretaceous. A broader comparison of detrital zircon age distributions in Jurassic–Cretaceous deposits across the south-eastern Verkhoyansk-Kolyma orogen illustrates that the Sugoi and Omsukchan basins did not form along the distal eastern portion of the Verkhoyansk passive margin, but in the Late Mesozoic back-arc basins.
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Lelono, Eko Budi. "The Jurassic-Cretaceous Paleogeography Of The Sula Area, North Maluku." Scientific Contributions Oil and Gas 34, no. 1 (February 15, 2022): 67–83. http://dx.doi.org/10.29017/scog.34.1.793.
Full textAbstract:
The study of paleogeography and hydrocarbon potentiality of the Sula area, North Maluku has been conducted by the Lemigas Exploration team. This paper specifically presents a paleogeography of the Jurassic-Cretaceous age of the Sula area as a part of the result of this study. In this paper, paleogeography means palaeoenvironment which is defined based on biostratigraphy. Data used in this paper are mostly secondary data obtained from National Data Center which is combined with primary data collected during field work campaign. The subsurface data analysis allows subdivision of 7 depositional sequences throughout Jurassic-Cretaceous succession. In fact, each sequence mostly consists of transgressive and highstand system tracts. Lowstand system tract only occurs in the earliest sequence. Sequences 1 (Bobong Formation), 2, 3 and 4 (Buya Formation) are assigned to the Jurassic age, whilst sequences 5, 6 and 7 (Buya Formation) are attributed to the Cretaceous age. Generally, the depositional environment of most sequences is getting deeper toward the North. The shallowest environment takes place in non-marine setting, whereas the deepest environment occurs in outer neritic (100m-200m). It is most likely that Jurassic-Cretaceous depocenter was situated in the northern part of the study area. However, it is required additional data to confirm this interpretation.
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SARKAR, DEBATTAM, SHUBHABRATA PAUL, RANITA SAHA, SUBHENDU BARDHAN, and PURBASHA RUDRA. "BODY SIZE TRENDS IN TRIGONIIDA BIVALVES FROM THE MESOZOIC KUTCH, INDIA." PALAIOS 37, no. 4 (April 14, 2022): 89–103. http://dx.doi.org/10.2110/palo.2020.046.
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ABSTRACT Although empirical testing of Cope's rule, the tendency for size to increase over time, has received significant attention in the last few decades, there is no consensus about the applicability of this rule across taxonomic levels. In the present study, we investigate the distribution of body size of Trigoniida bivalves, at order-, family-, genus- and species-level, through the Middle Jurassic and Early Cretaceous of the Kutch region in India. Our data suggest that the body size of Trigoniida bivalves did not vary significantly in the Middle–Late Jurassic, followed by an increase after the Jurassic–Cretaceous mass extinction boundary and a reduction in the late Early Cretaceous. Changes in relative sea-level and associated sedimentary facies composition generally exhibit poor correlation with the overall stasis, or no net body size change, displayed by Trigoniida bivalves. Body-size analysis across taxonomic hierarchy reveals that order-level trends are not a simple aggregation of trends at lower taxon levels. An important observation of our study is the body-size increase immediately in the aftermath of the Jurassic– Cretaceous mass extinction, a deviation from the general observation that size reduction occurs in post-extinction communities. We argue that this increase may be result of both ecological competition and evolutionary faunal turnover.
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Russell, Dale A. "The role of Central Asia in dinosaurian biogeography." Canadian Journal of Earth Sciences 30, no. 10 (October 1, 1993): 2002–12. http://dx.doi.org/10.1139/e93-176.
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Dinosaurian biogeography may have been largely controlled by the Mesozoic fragmentation of Pangea and the reassembly of its fragments into a new, boreal supercontinent (Laurasia). Although Late Triassic and Early Jurassic dinosaurs were globally distributed, Chinese assemblages were dominated by endemic forms from Middle Jurassic into Early Cretaceous time. The affinities of Aptian – Albian immigrants to Asia were strongest with North America and Europe rather than Gondwana, indicating that the northern and southern hemispheres had by then attained their biogeographic identity. This distinctiveness was maintained through Cretaceous time. Europe seems to have been a buffer area between Paleolaurasia and Gondwana; of the northern continents it was the most strongly influenced by Gondwana dispersants. Late Jurassic dinosaur assemblages in North America exhibited Gondwana affinities, but by Late Cretaceous time they were dominated by forms of Asian ancestry.
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Kosakowski, Paweł, Dariusz Więcław, Adam Kowalski, and Yuriy Koltun. "Assessment of hydrocarbon potential of Jurassic and Cretaceous source rocks in the Tarnogród-Stryi area (SE Poland and W Ukraine)." Geologica Carpathica 63, no. 4 (August 1, 2012): 319–33. http://dx.doi.org/10.2478/v10096-012-0025-3.
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Assessment of hydrocarbon potential of Jurassic and Cretaceous source rocks in the Tarnogród-Stryi area (SE Poland and W Ukraine) The Jurassic/Cretaceous stratigraphic complex forming a part of the sedimentary cover of both the eastern Małopolska Block and the adjacent Łysogóry-Radom Block in the Polish part as well as the Rava Rus'ka and the Kokhanivka Zones in the Ukrainian part of the basement of the Carpathian Foredeep were studied with geochemical methods in order to evaluate the possibility of hydrocarbon generation. In the Polish part of the study area, the Mesozoic strata were characterized on the basis of the analytical results of 121 core samples derived from 11 wells. The samples originated mostly from the Middle Jurassic and partly from the Lower/Upper Cretaceous strata. In the Ukrainian part of the study area the Mesozoic sequence was characterized by 348 core samples collected from 26 wells. The obtained geochemical results indicate that in both the south-eastern part of Poland and the western part of Ukraine the studied Jurassic/Cretaceous sedimentary complex reveals generally low hydrocarbon source-rock potential. The most favourable geochemical parameters: TOC up to 26 wt. % and genetic potential up to 39 mg/g of rock, were found in the Middle Jurassic strata. However, these high values are contradicted by the low hydrocarbon index (HI), usually below 100 mg HC/g TOC. Organic matter from the Middle Jurassic strata is of mixed type, dominated by gas-prone, Type III kerogen. In the Polish part of the study area, organic matter dispersed in these strata is generally immature (Tmax below 435 °C) whereas in the Ukrainian part maturity is sufficient for hydrocarbon generation.
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Ogg, James G., and William Lowrie. "Magnetostratigraphy of the Jurassic/Cretaceous boundary." Geology 14, no. 7 (1986): 547. http://dx.doi.org/10.1130/0091-7613(1986)14<547:motjb>2.0.co;2.
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Scotese, Christopher R. "Jurassic and cretaceous plate tectonic reconstructions." Palaeogeography, Palaeoclimatology, Palaeoecology 87, no. 1-4 (October 1991): 493–501. http://dx.doi.org/10.1016/0031-0182(91)90145-h.
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Hess, Hans. "Cyclocrinus, an enigmatic Jurassic–Cretaceous crinoid." Swiss Journal of Geosciences 101, no. 2 (July 25, 2008): 465–81. http://dx.doi.org/10.1007/s00015-008-1273-1.
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Devyatov, V. P. "EVOLUTION OF TERRIGENOUS SEDIMENTOGENESIS (С3–K) OF THE LENA-KHATANGA INTERFLUVES (NORTH OF THE SIBERIAN PLATFORM)." Geology and mineral resources of Siberia, no. 3 (October 2022): 17–29. http://dx.doi.org/10.20403/2078-0575-2022-3-17-29.
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Based on the analysis of geological and geophysical materials, data on the thickness, composition, conditions of formation and evolution of terrigenous sedimentogenesis of Upper Paleozoic, Triassic, Jurassic and Cretaceous deposits of the Lena-Khatanga interfluve are given, the relationship of sedimentation with large lineaments of the Earth’s crust and tectonic events is presented. The Late Paleozoic, Early Triassic, Jurassic-Cretaceous and Cenozoic stages of tectogenesis that completed the formation of structures are identified and confirmed.
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Shuster, Vladimir L., and Alexander Dziublo. "Substantiation of the prospects to discover large oil and gas accumulations in the Jurassic and pre-Jurassian deposits on the Kara Sea shelf." Georesursy 25, no. 1 (March 30, 2023): 67–74. http://dx.doi.org/10.18599/grs.2023.1.8.
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In order to replenish oil and gas reserves in the medium term and until the end of the century, it will be necessary to study new sediment complexes in promising regions of the country. One of these areas is the Kara Sea shelf, where large and giant gas condensate fields have already been discovered in the Cretaceous deposits, and the Pobeda field has been discovered on the eastern Prinovozemelsky shelf, with an oil deposit in the Lower-Middle Jurassic deposits and gas deposits in the Cretaceous. The article substantiates the prospects for the oil and gas potential of the Jurassic complex in the central part of the South Kara oil and gas region and the strategic need for geological exploration in the Jurassic and pre-Jurassic deposits of the region.
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Nechaev, Victor P., Frederick L. Sutherland, and Eugenia V. Nechaeva. "Metallogenic Evolution of Northeast Asia Related to the Cretaceous Turn of Geological Evolution." Minerals 12, no. 4 (March 24, 2022): 400. http://dx.doi.org/10.3390/min12040400.
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This study tests the hypothesis of Cretaceous Turn of Geological Evolution (CTGE). It uses the large dataset on mineral deposits of NE Asia compiled by the US Geological Survey in collaboration with Russian, Mongolian, Korean, and Japanese geological institutions. As predicted, the Triassic–Early Jurassic and Late Cretaceous–Paleogene geodynamic activities in NE Asia were simple, producing a relatively small amount of mineral deposits (94 and 132, respectively). In contrast, the greatly increased geodynamic activity around CTGE produced a huge amount of mineral deposits (288). The Jurassic–Early Cretaceous superplume-related melts were injected into accretionary wedges that formed along the Pacific–Eurasian margins, whereas adakitic and granitic magmas derived from the shallow slab and lower crust were intruded into the huge intracontinental region. The characteristic mineral deposits are represented by the unique Jurassic–Early Cretaceous plume-related Ti-Fe-V (+P + Cr-PGE + Au + diamond) ores. Other CTGE representatives are the porphyry Cu-Mo and Au (+Ag)-vein deposits, which formation, however, continued into the Late Cretaceous–Paleogene epoch. These deposits were generated by the slab- and crust-derived adakitic and granitic melts formed under influence of the expiring superplume and intensifying subduction. The Late Cretaceous–Paleogene epoch is indicated by a decreasing metallogenic activity in general, and an increasing role of subduction-related deposits in particular.
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Feldmann, Rodney M., Carrie E. Schweitzer, and William R. Wahl. "Ekalakia (Decapoda: Brachyura): the preservation of eyes links Cretaceous crabs to Jurassic ancestors." Journal of Paleontology 82, no. 5 (September 2008): 1030–34. http://dx.doi.org/10.1666/08-006.1.
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Description of a new species of crab, Ekalakia exophthalmops, brings to two the number of species within this Late Cretaceous genus from the upper mid-west in North America. Discovery of eyes and orbital structures in both species permits placement of the genus within the superfamily Glaessneropsoidea Patrulius, 1959 and family Glaessneropsidae Patrulius, 1959, extending the range of those taxa from the Late Jurassic into the Late Cretaceous. The extraordinarily large eyes relative to body size suggests that the Jurassic reef-dwelling crabs were adapted for a cryptic lifestyle which preadapted them for the deep-water, dysphotic, level-bottom habitat occupied by the Cretaceous descendants.
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Roy, Kaustuv. "Evolutionary history of Aporrhaidae (Gastropoda, Mollusca)." Paleontological Society Special Publications 6 (1992): 254. http://dx.doi.org/10.1017/s2475262200008145.
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The Aporrhaidae is an important family of marine gastropods whose members are characterized by an expanded apertural lip. A phylogenetic analysis of this clade confirmed its monophyly although a few of the constituent genera, as presently defined, are polyphyletic. Stage-level diversity data for the Northern Hemisphere genera gathered through fieldwork, visits to museum collections and from the literature indicate an initial radiation of this clade during the middle Jurassic. This radiation produced 9 genera by the end of Callovian. Similar levels of generic diversity were maintained throughout latest Jurassic and the earliest Cretaceous. During the Jurassic the aporrhaids appear to have been geographically restricted to Europe and Africa. However, given the paucity of Jurassic marine sediments on most continents, this distribution is probably biased although absences in Japan and North America are probably genuine. The later part of the early Cretaceous history of this group is characterized by a major faunal turnover which resulted in the extinction of over 70% of the Jurassic genera and the evolution of at least 10 new Cretaceous genera. The group reached its highest diversity during the Albian, followed by a slight decline during the Cenomanian. This diversity peak is at least partially attributable to the exceptional quality of preservation during the Albian which is unsurpassed in any Jurassic or Cretaceous stages except the Maastrichtian. The average diversity for the rest of the Cretaceous stages remained around 12 genera and by late Cretaceous the group achieved a global geographic distribution. The aporrhaids suffered a severe setback during the Maastrichtian when at least 75% of the genera went extinct. The stratigraphic data presently available does not provide enough resolution to determine whether this extinction coincided precisely with the K-T event. At the generic level this extinction does not seem to exhibit any selectivity based on geographic range. Of the three end-Cretaceous survivors, Drepanocheilus and Arrhoges were widespread geographically while the third, Aporrhais had a restricted distribution. Similarly the taxa that perished included both endemic genera and widespread ones like Quadrinervus. The Cenozoic history of the clade is characterized by very low levels of generic diversity and restricted geographic distribution with only two extant genera.From a macroevolutionary perspective, the late Neocomian turnover as well as the Maastrichtian extinction of aporrhaid genera are particularly interesting. The first event gave rise to a number of distinctive morphologies and coincided with the radiation of various groups of durophagous predators such as decapod crustaceans as well as with the rise of the carnivorous gastropods. The nature and timing of this change suggests that it could be a part of the broader Cretaceous faunal reorganization commonly known as the “Mesozoic marine revolution” (Vermeij, 1977). The end-Cretaceous event is interesting for its magnitude as well as its consequences. The aporrhaids maintained a remarkably stable generic diversity level from mid Jurassic to late Cretaceous, but never recovered from the Maastrichtian extinction. This pattern is in direct contrast to that exhibited by the sister group of Aporrhaidae, the Strombidae. The strombids exhibit extremely low generic diversity and restricted geographic distribution during the Cretaceous but radiated rapidly during the early Cenozoic. Such reciprocal diversity trends, combined with close phylogenetic relationship and functional similarity of the two groups as well as the presence of morphologic convergence, suggests extinction induced replacement and seems to be consistent with models proposed by, among others, Hallam (1987) and Rosenzweig & McCord (1991).
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Hoedemaeker, Ph J. "Tethyan-Boreal Correlations and the Jurassic-Cretaceous Boundary." Newsletters on Stratigraphy 25, no. 1 (September 19, 1991): 37–60. http://dx.doi.org/10.1127/nos/25/1991/37.
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