Dolerites intrusives dans le Lias et le Dogger d'Andalousie: leurs differenciations pegmatitiques alcalines et aureoles de metamorphisme

1962 ◽  
Vol S7-IV (3) ◽  
pp. 461-470
Author(s):  
Robert Busnardo ◽  
Maurice Chenevoy
Keyword(s):  
Middle Jurassic ◽  
Thermal Characteristics ◽  
Lower Jurassic ◽  
Southern Spain ◽  
Jurassic Limestone

Abstract Three newly-discovered occurrences of upper Dogger (?) (middle Jurassic) dolerite in upper Lias to Dogger (Jurassic) formations of the Priego de Cordoba area of southern Spain resemble other dolerites of the region. The Las Navas dike and the Buitron sills are in Dogger marl, and the Las Lomas sill is in upper Lias (lower Jurassic) limestone. The contact metamorphic zones are proportional to the thickness of the tabular bodies, and exhibit only thermal characteristics. The thick Las Lomas sill transformed the initial six meters of overlying limestone to garnetiferous marble. Leucocratic enclaves of pegmatite are characterized by about 58 percent SiO <sub>2</sub> as contrasted with about 50 percent in the dolerite.

Provenance of Jurassic sedimentary rocks of south-central Quesnellia, British Columbia: implications for paleogeography

2004 ◽  
Vol 41 (1) ◽  
pp. 103-125 ◽  
Author(s):  
Nathan T Petersen ◽  
Paul L Smith ◽  
James K Mortensen ◽  
Robert A Creaser ◽  
Howard W Tipper
Keyword(s):  
Detrital Zircon ◽  
Middle Jurassic ◽  
Sedimentary Rocks ◽  
Source Area ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Late Triassic ◽  
Nd Isotopes ◽  
South Central ◽  
History Of

Jurassic sedimentary rocks of southern to central Quesnellia record the history of the Quesnellian magmatic arc and reflect increasing continental influence throughout the Jurassic history of the terrane. Standard petrographic point counts, geochemistry, Sm–Nd isotopes and detrital zircon geochronology, were employed to study provenance of rocks obtained from three areas of the terrane. Lower Jurassic sedimentary rocks, classified by inferred proximity to their source areas as proximal or proximal basin are derived from an arc source area. Sandstones of this age are immature. The rocks are geochemically and isotopically primitive. Detrital zircon populations, based on a limited number of analyses, have homogeneous Late Triassic or Early Jurassic ages, reflecting local derivation from Quesnellian arc sources. Middle Jurassic proximal and proximal basin sedimentary rocks show a trend toward more evolved mature sediments and evolved geochemical characteristics. The sandstones show a change to more mature grain components when compared with Lower Jurassic sedimentary rocks. There is a decrease in εNdT values of the sedimentary rocks and Proterozoic detrital zircon grains are present. This change is probably due to a combination of two factors: (1) pre-Middle Jurassic erosion of the Late Triassic – Early Jurassic arc of Quesnellia, making it a less dominant source, and (2) the increase in importance of the eastern parts of Quesnellia and the pericratonic terranes, such as Kootenay Terrane, both with characteristically more evolved isotopic values. Basin shale environments throughout the Jurassic show continental influence that is reflected in the evolved geochemistry and Sm–Nd isotopes of the sedimentary rocks. The data suggest southern Quesnellia received material from the North American continent throughout the Jurassic but that this continental influence was diluted by proximal arc sources in the rocks of proximal derivation. The presence of continent-derived material in the distal sedimentary rocks of this study suggests that southern Quesnellia is comparable to known pericratonic terranes.

A propos de l'age de la serie ophiolitique dans les Dinarides yougoslaves; la coupe de Mihajlovici aux confins de la Serbie et du Montenegro (region de Plevlja, Yougoslavie)

1964 ◽  
Vol S7-VI (1) ◽  
pp. 107-112 ◽  
Author(s):  
Jean Aubouin ◽  
Jean Paul Cadet ◽  
Jean Paul Rampnoux ◽  
Gonzague Dubar ◽  
Pierre Marie
Keyword(s):  
Upper Jurassic ◽  
Lower Jurassic ◽  
Jurassic Limestone

Abstract The Mihajlovici area in southwestern Yugoslavia is a mosaic of fault blocks produced by two sets of large faults, trending NW and NE. The horsts are lower Jurassic limestone, and the grabens are occupied by diabase-radiolarite, known as the ophiolitic series, of lower Malm age (upper Jurassic). Abundant ammonites and microfauna identify several horizons, notably the Toarcian (upper Lias, i.e., lower Jurassic) and the uppermost bed of the lower Malm, thus fixing the Malm age of the ophiolitic series.

Observations sur la region de Longobucco (Italie meridionale)

1962 ◽  
Vol S7-IV (5) ◽  
pp. 719-720 ◽  
Author(s):  
Claude Afchain
Keyword(s):  
Middle Jurassic ◽  
Sedimentary Basin ◽  
Lower Jurassic ◽  
Sedimentary Sequence

Abstract The Longobucco area displays a secondary sedimentary basin transgressive on a granite-phyllite basement. The sedimentary sequence begins with lower Jurassic quartzose conglomerate containing granite and phyllite. The conglomerate is overlain by a homogeneous calcareous marl which forms a large part of the basin and has been divided into lower, middle and upper Liassic (lower Jurassic) by dating with brachiopods, pelecypods and cephalopods. The middle Jurassic consists of red limestones of the Torrente Colognati valley. Cretaceous rocks are not present, probably because of erosion rather than non-deposition. Tertiary rocks begin with either the Paleocene or Eocene as evidenced by the abundance of Distichoplax in the microfauna.

scholarly journals Facies analysis of the Lower-Middle Toarcian in the External Subbetic (provinces of Murcia and Granada, Southern Spain): palaeoenvironmental conditions

2019 ◽  
Author(s):  
José Miguel Molina ◽  
Luis M Nieto
Keyword(s):  
Lower Jurassic ◽  
Southern Spain ◽  
Tectonic Activity ◽  
Oceanic Circulation ◽  
Carbonate Platforms ◽  
The South ◽  
Sea Floor ◽  
Western Tethys ◽  
Oceanic Anoxic Event ◽  
Facies Types

Toarcian sedimentary rocks are well recorded in the Subbetic (Betic External Zones, Southern Spain) as part of the Zegrí Formation (upper Pliensbachian-Aalenian). These rocks were deposited in the South Iberian Palaeomargin in the Western Tethys. We study the lower-middle Toarcian facies in two sections in the External Subbetic and their palaeoenvironmental interpretation. The lower-middle Toarcian have more than 160 m in thickness, the maximum for this time in all the Betic External Zones. Five types of lithofacies are differentiated: 1) Grey-yellow marl-marly limestone rhythmite and limestones (lower part of the Polymorphum Zone); 2) dark marls (upper part of the Polymorphum Zone and lower part of the Serpentinum Zone); 3) thin bedded grey-yellow limestones, locally with chert and abundant slumps (upper part of the Serpentinum Zone); 4) grey marls and marly limestones (Bifrons and Gradata Zones); and 5) yellow-brown laminated calcisiltites and calcarenites, intercalated in facies 3 and 4. Facies 1 to 4 are interpreted as hemipelagites, deposited by the slow accumulation, on a quiet sea floor of biogenic and very fine terrigenous particles. Facies 2 was deposited in rather depleted oxygen conditions with slightly dysoxic bottom waters but discarding completely anoxic conditions. The Toarcian Oceanic Anoxic Event (T-OAE) is recorded in this facies 2 by some increase of total organic carbon (maximum of 1.05 wt.%) and redox sensitive elements, the decrease of CaCO3, and the negative excursion of δ13C observed at the base of Serpentinum Zone. Facies 5 are mainly peloidal grainstone with bioclasts (brachiopods, bivalves, and echinoderms), ooids and allochthonous shallow water foraminifera, and packstone-wackestone of bioclasts (mainly radiolarians) and peloids. This facies 5 with parallel lamination and locally with normal grading, low angle, wavy, and hummocky cross stratification is interpreted as tempestites related with tropical cyclones, and/or internalites. The influence of adjacent emerged lands and carbonate platforms, differential subsidence by local tectonics, sediment winnowing by currents, sedimentation rates, bioturbation, and diagenesis, may have had more importance in the distribution of the facies types than depth. The evolution during the lower-middle Toarcian was mainly controlled by tectonics after the Pliensbachian break-up of the Lower Jurassic platform, together with a relative sea-level change. Also the beginning of basaltic submarine volcanism to the South in some Median Subbetic areas had influence. The diversified physiography related to synsedimentary tectonic activity and oceanic circulation patterns, determined different intensities of winnowing and oxygenation on the sea-floor. The T-OAE is recorded in the base of Serpentinum Zone. The general re-oxygenation after the T-OAE could be favoured by changes in oceanic currents and by the tempestite/internalite inputs during the upper part of Serpentinum and Bifrons zones.

Large volume silicic volcanism along the proto-Pacific margin of Gondwana: lithological and stratigraphical investigations from the Antarctic Peninsula

1999 ◽  
Vol 136 (1) ◽  
pp. 1-16 ◽  
Author(s):  
TEAL R. RILEY ◽  
PHILIP T. LEAT
Keyword(s):  
Antarctic Peninsula ◽  
Middle Jurassic ◽  
East Coast ◽  
Volcanic Rocks ◽  
Lower Jurassic ◽  
Fossil Flora ◽  
Metasedimentary Rocks ◽  
Close Relationship ◽  
Pacific Margin ◽  
The Antarctic

Jurassic magmatism in western Gondwana produced the most voluminous episode of continental volcanism in the Phanerozoic era. During the Early to Middle Jurassic, some 2.5–3 million km3 of dominantly basalt, and to a lesser extent rhyolite, were erupted onto a supercontinent in the early stages of break-up. The major silicic portion of the Gondwana magmatic province is exposed in Patagonian South America. The volcanic rocks of Patagonia have been collectively termed the Chon-Aike Province and constitute one of the world's most voluminous silicic provinces. The volcanic rocks are predominantly pyroclastic, dominated by ignimbrite units of rhyolite composition. Volcanic rocks crop out sporadically across much of the once contiguous Antarctic Peninsula, and are considered to form an extension of the Chon-Aike Province. A continuation of the province to include the Antarctic Peninsula would extend its strike length along the active Pacific margin by c. 2000 km.Volcanic rocks exposed along the east coast of the Antarctic Peninsula, defined here as the Mapple Formation, are also dominated by rhyolitic ignimbrite flows, with individual units up to 80 m in thickness, and a total thickness of c. 1 km. The ignimbrites vary in degree of welding, from high-grade rheomorphic ignimbrites with parataxitic textures, to unwelded, lithic-rich ignimbrites. Rhyolite lava flows, air-fall horizons, debris flow deposits and epiclastic deposits are volumetrically minor, occurring as interbedded units within the ignimbrite succession.The lithology and stratigraphy of the Jurassic volcanic rocks of the Mapple Formation are presented, and comparisons are made to the Chon-Aike Province. A consistent stratigraphy of Permo-Triassic metasedimentary rocks, unconformably overlain by terrestrial mudstone–siltstone sequences, which are in turn conformably overlain by largely silicic, subaerial volcanic rocks, is present at several localities along the Antarctic Peninsula, and at localities in the Chon-Aike Province. Precise (zircon U–Pb) Middle Jurassic ages exist for two volcanic formations from the Antarctic Peninsula, and a Middle–Lower Jurassic age has been suggested for the underlying sedimentary formations based on fossil flora analysis. The Antarctic Peninsula chronostratigraphy, coupled with lithological similarities, indicate a close relationship to those sequences of the Chon-Aike province.

A new genus and species of damsel-dragonfly from the Middle Jurassic of Inner Mongolia (Odonata: Campterophlebiidae)

2020 ◽  
Vol 3 (4) ◽  
pp. 357-360
Author(s):  
ANDRÉ NEL ◽  
DIYING HUANG
Keyword(s):  
Middle Jurassic ◽  
Inner Mongolia ◽  
Late Jurassic ◽  
New Genus ◽  
Lower Jurassic ◽  
Northeastern China ◽  
Large Species ◽  
New Genus And Species ◽  
Unique Shape ◽  
Anal Area

The Campterophlebiidae is the largest family of fossil damsel-dragonflies, containing more than 60 species described from Lower Jurassic–Lower Cretaceous strata of Europe and Asia. This group is especially diverse in the Middle–Late Jurassic strata in Inner Mongolia, northeastern China, with some very large species (Zhang et al., 2006, 2008, 2013; Nel et al., 2007, 2008, 2009; Petrulevičius et al., 2011; Li et al., 2013; Zhang et al., 2013; Zheng et al., 2016, 2017). Thus it is surprising that we found a new representative of these damsel-dragonflies, belonging to a group of genera characterized by a very particular shape of the forewing cubito-anal area. This fossil has a unique shape of the forewing median vein, allowing its attribution to a new genus and species. It increases our knowledge about the palaeobiodiversity of this impressive group of Odonata.

The Beatrice Field, Block 11/30a, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 245-252 ◽  
Author(s):  
V. Stevens
Keyword(s):  
Oil Recovery ◽  
Middle Jurassic ◽  
Water Injection ◽  
Lower Jurassic ◽  
Main Field ◽  
Field Boundary ◽  
Hydrocarbon Trap ◽  
Electrical Submersible Pumps ◽  
Moray Firth ◽  
Jurassic Rocks

AbstractThe Beatrice Field was discovered in 1976 in Block 1l/30a within the Inner Moray Firth Basin. The reservoir consists of multilayered Lower and Middle Jurassic sediments containing a STOIIP of 480 MMBBL of high wax crude oil. The reservoir sequence comprises 1100 ft of Hettangian (Lower Jurassic) to Callovian (Middle Jurassic) sandstones, siltstones and claystones. The Beatrice Field is co-sourced by a combination of Devonian and Jurassic rocks. The hydrocarbon trap comprises a tilted faultblock, the top of which is truncated by the main field boundary fault. The field has low energy, and the Pi of 2897 psi at 6500 ft TVSS, GOR 126 SCF/STBBL and Ph of 635 psi, together with the poor aquifer influx, necessitated the development of water injection from the start of production and use of electrical submersible pumps in all wells. Ultimate oil recovery is expected to be 146 MMBBL. The field has been developed with four platforms at three sites in 133 ft waterdepth. The crude is transported 42 miles by peline to the dedicated oil terminal at Nigg on the Cromarty Firth.

The Beryl Field, Block 9/13, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 33-42 ◽  
Author(s):  
C. A. Knutson ◽  
I. C. Munro
Keyword(s):  
North Sea ◽  
Middle Jurassic ◽  
Oil And Gas ◽  
Upper Jurassic ◽  
Lower Jurassic ◽  
Gas Production ◽  
Upper Triassic ◽  
Oil Field ◽  
Oil And Gas Production ◽  
The North

AbstractThe Beryl Field, the sixth largest oil field in the UK sector of the North Sea, is located within Block 9/13 in the west-central part of the Viking Graben. The block was awarded in 1971 to a Mobil operated partnership and the 9/13-1 discovery well was drilled in 1972. The Beryl A platform was emplaced in 1975 and the Beryl B platform in 1983. To date, ninety-five wells have been drilled in the field, and drilling activity is anticipated into the mid-1990s.Commercial hydrocarbons occur in sandstone reservoirs ranging in age from Upper Triassic to Upper Jurassic. Structurally, the field consists of a NNE orientated horst in the Beryl A area and westward tilted fault blocks in the Beryl B area. The area is highly faulted and complicated by two major and four minor unconformities. The seal is provided by Upper Jurassic shales and Upper Cretaceous marls.There are three prospective sedimentary sections in the Beryl Field ranked in importance as follows: the Middle Jurassic coastal deltaic sediments, the Upper Triassic to Lower Jurassic continental and marine sediments, and the Upper Jurassic turbidites. The total ultimate recovery of the field is about 800 MMBBL oil and 1.6 TCF gas. As of December 1989, the field has produced nearly 430 MMBBL oil (primarily from the Middle Jurassic Beryl Formation), or about 50% of the ultimate recovery. Gas sales are scheduled to begin in the early 1990s. Oil and gas production is forecast until licence expiration in 2018.The Beryl Fields is located 215 miles northeast of Aberdeen, about 7 miles from the United Kingdom-Norwegian boundary. The field lies within Block 9/13 and covers and area of approximately 12 000 acres in water depths ranging from 350-400 ft. Block 9/13 contains several hydrocarbon-bearing structures, of which the Beryl Fields is the largest (Fig. 1). The field is subdivided into two producing areas: the Beryl Alpha area which includes the initial discovery well, and the Beryl Bravo area located to the north. The estimated of oil originally in place is 1400 MMBBL for Beryl A and 700 MMBBL for Beryl B. The fiel has combined gas in place of 2.8 TCF, consisting primarily of solution gas. Hydrocarbon accumulations occur in six reservoir horizons ranging in age from Upper Triassic to Upper Jurassic. The Middle Jurassic (Bathonian to Callovian) age Beryl Formation is the main reservoir unit and contains 78% of the total ultimate recovery.The field was named after Beryl Solomon, the wife of Charles Solomon, who was president of Mobil Europe in 1972 when the field was discovered. The satellite fields in Block 9/13 (Nevis, Ness and Linnhe) are named after Scottish lochs.

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