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Pedogenic and lacustrine features of the Brushy Basin Member of the Upper Jurassic Morrison Formation in western Colorado: Reassessing the paleoclimatic interpretations

Tanner L., Galli K., Lucas S.

Volumina Jurassica

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2014

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Vol. 12, no. 2

115--130

EN

Study of the pedogenic features of the Upper Jurassic Morrison Formation in western Colorado, USA, shows a clear difference in the types of paleosols between the strata of the lower and upper Brushy Basin Member. Lower Brushy Basin paleosols are mostly calcareous Aridisols with Stage I through Stage III calcrete Bk horizons, abundant root traces, occasional vertic features, but only rarely with ochric epipedons. Upper Brushy Basin paleosols are mainly thicker and commonly display ochric epipedons and well-developed Bt and Bw horizons. We assign these paleosols to the order Inceptisol. Limestones occur in the Brushy Basin Member and include both uniformly micritic limestones and limestones with strongly brecciated textures. The former contain sparse body fossils and charophyte debris, while the latter are characterized by clotted-peloidal fabrics with circumgranular cracking and silica replacement. We interpret these limestones as the deposits of carbonate in small water bodies on a low-gradient flood plain, with the textures resulting from pedogenic reworking of the carbonate sediment. We find no evidence for the presence of extensive lacustrine or wetlands (Lake T’oo’dichi’) deposits in the study area. The paleoclimate suggested by all of these features is strongly seasonal, but subject to variations on orbital (precessional and higher) timescales causing intervals of semi-aridity during weaker monsoons, to alternate with sub-humid periods during stronger monsoons. The apparent long-term change in climate during Brushy Basin deposition potentially resulted from northward drift of North America.

2

Lithostratigraphy of the Jurassic San Rafael Group from Bluff to the Abajo Mountains, southeastern Utah: Stratigraphic relationships of the Bluff Sandstone

Lucas S.

Volumina Jurassica

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2014

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Vol. 12, no. 2

55--68

EN

Measured sections of Jurassic San Rafael Group strata correlated by lithostratigraphy along an ~60 km transect between Bluff and the Abajo Mountains in southeastern Utah indicate that: (1) the Carmel Formation is continuous and disconformable on the Navajo Sandstone (J-2 unconformity); (2) the Entrada Sandstone (Slick Rock Member) is continuous and conformable on the Carmel; (3) the Summerville Formation is continuous and does not intertongue with the Entrada (its base is the J-2 unconformity); (4) the Bluff Sandstone grades northward into the upper Summerville south of the Abajo Mountains; (5) the Recapture Member of the Bluff is physically continuous with at least part of the Tidwell Member of the Summerville; and (5) the base of the Salt Wash Member of the Morrison Fm. is a pervasive unconformity (J-5) with demonstrable local stratigraphic relief of up to 14 m. These observations counter previous claims of extensive Entrada-Summerville intertonguing in southeastern Utah and do not support recognition of depositional sequence boundaries in the Entrada and Summerville lithosomes. Though Entrada deposition may have been by a wet eolian system, its southeastern Utah outcrops are well to the south/ southeast of any marine and paralic facies with which the Entrada intertongues.

3

Jurassic vertebrate bromalites of the western United States in the context of the global record

Hunt A., Lucas S.

Volumina Jurassica

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2014

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Vol. 12, no. 2

151--158

EN

The bromalite record of the western United States is quite limited, especially in contrast to the Triassic and Cretaceous records of the same region. Indeed, there are only a handful of well documented vertebrate bromalites from the Jurassic strata of the western USA, including: (1) coprolites from the nonmarine Early Jurassic Glen Canyon Group; (2) consumulites and evisceralites from the Middle Jurassic Todilto and Sundance formations; and (3) consumulites, putative coprolites and pseudobromalites from the nonmarine Upper Jurassic Morrison Formation. Early Jurassic red beds are notably less fossiliferous than those of the Triassic (e.g., contrast the fossil record of the Chinle and Glen Canyon groups). The Middle Jurassic of the region includes several eolianites and sabkha-like deposits representing environments that preserve few bromalites. The Upper Jurassic Morrison Formation contains abundant vertebrate body fossils and many tracks but very few bromalites in contrast to many broadly similar fluvial deposits of Triassic and Cretaceous age in the same region. The global bromalite record also appears to be depauperate in the Jurassic, with a few exceptions such as marine shales and lithographic limestones in Europe (e.g., Lower Jurassic of England, Upper Jurassic Solnhofen Limestone of Bavaria). This relative lack of a global Jurassic bromalite record may in part be more a result of a lack of collection and study. However, the relative lack of nonmarine bromalites is clearly influenced by high sea levels in the Early Jurassic, a paucity of Middle Jurassic nonmarine vertebrate-bearing units and a lack, or lack of recognition of, bromalites in major Upper Jurassic nonmarine vertebrate faunas (e.g., China, Tanzania, Portugal, etc.). In the Western United States there is clearly a need for more detailed examination of known specimens (e.g., putative Morrison coprolites) and a focus on collecting more examples.

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Folding in the Middle Jurassic Todilto Formation, New Mexico-Colorado, USA

Lucas S., Krainer K., Berglof W.

Volumina Jurassica

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2014

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Vol. 12, no. 2

39--54

EN

The Middle Jurassic (Callovian) Todilto Formation of northwestern New Mexico–southwestern Colorado, USA, is a carbonate/evaporite lithostratigraphic unit that was deposited in a large paralic salina culminated by a gypsiferous evaporitic lake. Intraformational folds of the limestone-dominated lower part of the Todilto Formation (Luciano Mesa Member) range in scale from millimeters to meters, and many of the large folds are the loci of uranium mineralization. A diverse literature has attributed the formation of intraformational folds of the Todilto Formation to several causes, including syndepositional or postdepositional tectonics, soft-sediment deformation due to sediment loading or gravity sliding, diagenetic alteration (primarily the hydration/crystallization of gypsum/anhydrite), the growth of stromatolitic bioherms or the formation of tepee-like structures. We examine in detail two characteristic outcrops of intraformational folds in the Todilto Formation, in west-central New Mexico, to conclude that folds and domal structures present in the Todilto limestone facies at different stratigraphic levels and at different scales have resulted from varied processes that produced dome-like stromatolitic mounds, tepee-like structures, small-scale enterolithic folds and large-scale folds of likely diagenetic origin.

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Influence of incorporation phase change materials, PCM, granulates on workability, mechanical strenght and aesthetical appearance of lime and gypsum mortars

Cunha S., Lucas S., Aguiar J., Ferreira V., Braganca L.

Architecture Civil Engineering Environment

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2013

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Vol. 6, no. 3

39--48

EN

In a society with a high growth rate of comfort, the need to minimize the currently high energy consumption by taking advantage of renewable energy sources arises. The mortars with incorporation of phase change materials (PCM) have the ability to regulate the temperature inside buildings, contributing for an increase in thermal comfort levels and a reduction of the use of heating, ventilation and air conditioning (HVAC) equipment, using only the energy supplied by the sun. Therefore, the application of phase change materials (PCM) comes as a possible solution in an attempt to solve, or at least minimize, the massive energetic consumption related to buildings. This research intends to understand the influence of microcapsules of phase change materials on mortars. The mortars studied in this work are mixed mortars of lime and gypsum. The proportion of PCM is 0%, 10%, 20% and 30%. In order to minimize some problems associated with cracking of the mortars, the incorporation of nylon fibers and superplasticizer was tested. A study of mechanical characteristics and some sensitivity tests to qualify the cracking of the fifteen compositions were carried out. It can be concluded that the use of PCM microcapsules in mixed mortars of lime and gypsum can be seen as a viable solution for applications in the construction industry once they present a compromise between their strength and aesthetic appearance.

PL

W społeczeństwie o wysokiej stopie wzrostu komfortu, powstaje potrzeba zminimalizownia wysokiego zużycia energii poprzez wykorzystanie źródeł odnawialnych. Zaprawy z zawartością materiałów zmieniających fazę (PCM) posiadają zdolność do regulowania temperatury wewnątrz budynków, przyczyniając się do zwiększenia poziomu komfortu cieplnego i zmniejszenia wykorzystania ogrzewania, wentylacji i klimatyzacji ( HVAC), wykorzystując tylko energię słoneczną. W związku z tym, stosowanie materiałów zmieniających fazę (PCM) może zmniejszać zapotrzebowanie energetyczne budynków. Przedstawione badania miały na celu zrozumienie wpływu mikrokapsułek na przemiany fazowe w zaprawach. Badane zaprawy składały się z wapna i gipsu. Proporcja PCMwynosiła 0%, 10%, 20% i 30% .Wcelu zminimalizowania niektórych problemów związanych z pękaniem zapraw, wprowadzenie włókna nylonowych i superplastyfikatory. Badanie właściwości mechanicznych i wrażliwości na pękanie przeprowadzono na piętnastu zaprawach. Badania wykazaly, że korzystanie z mikrokapsułek PCM w zaprawach z wapna i gipsu może być realnym rozwiązaniem dla zastosowań w budownictwie.

6

The Whitmore Point Member of the Moenave Formation: Early Jurassic Dryland Lakes on the Colorado Plateau, Southwestern USA

Tanner L., Lucas S.

Volumina Jurassica

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2008

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Vol. 6, no. 1

11-21

EN

The Lower Jurassic Whitmore Point Member of the Moenave Formation in Arizona-Utah, USA, comprises fish- and coprolite-bearing shales, siltstones, sandstones, and minor limestones. These facies were deposited in ephemeral and perennial lakes subject to episodic desiccation and incursions of coarse clastics during floods. Meromictic conditions developed during perennial episodes, probably due to salinity stratification, which enhanced preservation of organic matter in gray to black shales. These lakes formed on the floodout of a north-northwest oriented (relative to modern geography) system of mainly ephemeral streams on a broad and open floodplain. The Whitmore Point Member both overlies and interfingers laterally with alluvial red-bed facies of the Dinosaur Canyon Member of the Moenave Formation. The vertical transition from alluvial to lacustrine sedimentation recorded by the Dinosaur Canyon and Whitmore Point members of the Moenave Formation most probably resulted from a eustatically-controlled rise in base level during the Early Jurassic (Hettangian). The Dinosaur Canyon Member also interfingers laterally with eolian dune deposits of the Wingate Sandstone, which was deposited by winds that reworked coastal plain sediments to the north of the study area. Thus, on this part of the Colorado Plateau, fluvial, lacustrine and eolian sedimentary facies were deposited contemporaneously in laterally adjacent paleoenvironments.

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Tetrapod trace fossils from lowermost Jurassic strata of the Moenave Formation, northern Arizona, USA

Tanner L., Lucas S.

Volumina Jurassica

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2008

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Vol. 6, no. 1

133-141

EN

At Moenkopi Wash along the Ward Terrace escarpment of northern Arizona strata of the upper Dinosaur Canyon Member of the Moenave Formation contain sedimentary structures we interpret as casts of tetrapod burrows. Sandstone casts and in situ burrows occur concentrated in two horizons that extend several hundred meters along the Ward Terrace escarpment. The structures, hosted in beds of eolian sandstone, form interconnecting networks of burrows that branch at right angles. Individual burrow casts have sub-circular cross sections and consist of nearvertical tunnels and horizontal to low-angle galleries that connect to larger chambers. Most burrow casts measure 5 to 15 cm in diameter, are filled by sandstone of similar grain size as the host rock, and have walls that are unlined and lack external ornamentation. Bedding plane exposure of the lower horizon reveals that the density of burrows exceeds 30 vertical tunnels per square meter. One exposure in the upper horizon reveals burrows concentrated in a mound-like structure with 1 m of relief. Rhizoliths, distinguished from burrows by their typical smaller diameters, calcareous infilling, and downward branching, co-occur with these burrows in the upper horizon. The fossil burrows in the Moenave Formation appear to have been constructed by a fossorial tetrapod with social behavior similar to the modern Mediterranean blind mole-rat. Although no skeletal remains are associated with the burrows, the fossil record suggests that the most likely producers of the Moenave burrows were tritylodontid cynodonts.

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Global Jurassic tetrapod biochronology

Lucas S.

Volumina Jurassica

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2008

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Vol. 6, no. 1

99-108

EN

Jurassic tetrapod fossils are known from all of the continents, and their distribution documents a critical paleobiogeographic juncture in tetrapod evolution – the change from cosmopolitan Pangean tetrapod faunas to the provincialized faunas that characterize the late Mesozoic and Cenozoic. Two global tetrapod biochronological units (faunachrons) have been named for the Early Jurassic – Wassonian and Dawan – and reflect some Early Jurassic tetrapod cosmopolitanism. However, after the Dawan, a scattered and poorly-dated Middle Jurassic tetrapod record and a much better understood Upper Jurassic tetrapod record indicate that significant provincialization of the global tetrapod fauna had begun. Middle Jurassic tetrapod assemblages include distinct local genera of sauropod dinosaurs, which are large, mobile terrestrial tetrapods, and this suggests marked provinciality by Bajocian time. The obvious provincialism of well known Chinese Middle-Upper Jurassic dinosaur faunas also documents the end of tetrapod cosmopolitanism. The distribution of some Late Jurassic dinosaur taxa defines a province that extended from the western USA through Europe into eastern Africa. Provincial tetrapod biochronologies have already been proposed for this province and for the separate eastern Asian Late Jurassic province. Tetrapod footprints only identify two global assemblage zones, one of Early Jurassic and the other of Middle-Late Jurassic age. The incomplete state of Jurassic tetrapod biochronology reflects both an inadequate record with poor temporal constraints and a relative lack of study of the biostratigraphy of Jurassic fossil vertebrates.

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Proposal of the Muller Canyon section (New York Canyon area, Nevada, USA) as stratotype for the Triassic/Jurassic boundary

Guex J., Taylor D., Rakús M., Bartolini A., Atudorei V., Carter E., Lucas S.

Volumina Jurassica

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2006

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Vol. 4, no. 1

283-285

EN

Completeness of the sedimentary and biostratigraphic record is the most important characteristic of a global stratotype intended to record the boundary between two geological stages. Such a reference section must also contain fossils with proven chronological value. In the Jurassic, ammonites are usually considered the ideal chronological marker and all high-resolution zonations concerning that period are based on this fossil group. Figure 1 demonstrates that the Muller Canyon section (New York Canyon area, Nevada, USA) provides by far the most complete biochronological ammonite sequence known in the world for this interval of time. The oldest Jurassic ammonites found in the area are the smooth Psiloceras tilmanni and P. spelae, which are characterized by nodes in their earliest stage of development (Knötchenstadium). Odoghertyceras, a genus found also in Peru and Canada, occurs just above that fauna. Other smooth ammonites found between the first occurrence of P. spelae and the last occurrence of Choristoceras crickmayi belong to a group that we call "intermediate phylloceratids". Such forms lack the nodose juvenile stage and are geometrically intermediate between rhacophyllitids and psiloceratids. In our region, C. crickmayi (younger than C. marshi) co-occurs with the last Arcestes, Placites and abundant Rhacophyllites. In our sections we have found the first Jurassic-type bivalves below the first occurrence of Psiloceras, in beds that we assign to the topmost Rhaetian. In our view, the occurrence of bivalves is strongly controlled by the nature of the sediments and by local ecological conditions and this group does not seem suitable for use as index for the base of the Jurassic. The absence of Triassic ammonoids in the classical NW European sections precludes the possibility of defining the stratotype for the Triassic/Jurassic boundary (TJB) in that region and the ammonite faunas are not well diversified in the classical Tethyan Alpine sections. At present, there are three potentially good GSSP candidates: Chilingote (Peru), Kunga Island (BC, Canada) and Muller Canyon (Nevada). As far as ammonite record is concerned, Nevada ranks foremost. However, an interesting solution would be to propose the Kunga Island section (British Columbia) as parastratotype because it records a complete sequence of radiolarians across this interval, and this group is not preserved around the TJB in the New York Canyon area.

10

Onset of erg sedimentation during the Early Jurassic on the Colorado Plateau, southwestern U.S.A.: climatic, eustatic and tectonic controls

Tanner L., Lucas S.

Volumina Jurassica

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2006

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Vol. 4, no. 1

106-106

EN

Deposition of the Moenave and Wingate formations took place during the latest Triassic to Early Jurassic in a mosaic of terrestrial subenvironments including fluvial, lacustrine, and eolian. Fluvial-lacustrine processes dominated Moenave deposition, which included channelized flow in ephemeral to perennial streams, unconfined flow (sheetwash) in interchannel areas, ephemeral lakes (playas), and perennial lakes that were subject to episodic desiccation. The Moenave terminal floodplain, which was dotted by broad, shallow lakes, interfingered with the Wingate erg, where eolian processes dominated. The Moenave-Wingate outcrop belt exposes a north-south lithofacies gradient from distal (erg margin) to proximal (erg interior) as dominantly fluvial-lacustrine lithofacies in the north are replaced by mainly eolian dune and interdune deposits to the south, recording encroachment of the Wingate erg. The prevalence of ephemeral stream and eolian environments during deposition of these strata indicates a seasonally arid climate during the latest Triassic to earliest Jurassic. We see no sedimentologic evidence for significant climate change at the Triassic/Jurassic boundary, or at any time encompassed by this sedimentary succession. The growth and incursion of the Wingate erg into the Moenave fluvial system may have been driven by the availability of sediment in the up-wind source area, the coastal plain and coastline to which the Moenave streams delivered sediment. We interpret a eustatic signal as responsible for formation of this erg as long-term regression during the Rhaetian and continued Hettangian low-stand exposed a broader area of shallow marine sediments to eolian reworking. Preservation of the erg deposits may have been enhanced by tectonically controlled accommodation space as continental shortening led to crustal flexure during the Early Jurassic.

11

Criterion for definition of the Triassic/Jurassic boundary

Lucas S., Guex J., Tanner L.

Volumina Jurassica

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2006

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Vol. 4, no. 1

291-291

EN

The criterion for definition of the Triassic/Jurassic boundary (TJB) should be a marker event of optimal global correlateability. Only an ammonite event meets this criterion; other potential marker events for definition of the TJB have less correlation potential. Since the 1960s, the LO of the ammonite Psiloceras (usually the species P. planorbis) has provided the working definition of the TJB. However, other criteria for boundary definition have been advocated, including a change in the bivalve fauna (LO of Agerchlamys), a sudden negative excursion of carbon isotopes and the LO of Psiloceras tilmanni, which precedes the LO of P. planorbis. Other criteria that can be advocated include the supposed TJB mass extinction, the HO (highest occurrence) of conodonts or a significant evolutionary turnover of radiolarians. Distinction of the Triassic and Jurassic systems in marine biostratigraphy has a long tradition rooted in ammonite biostratigraphy. This is because the ceratitedominated ammonite faunas of the Triassic virtually disappeared across the system boundary and were totally replaced by the smooth-shelled psiloceratids of the Early Jurassic. Because of the long history of study of this ammonite turnover, its details are extremely well documented on a global scale, especially in western North America, South America and Western Europe. This ammonite turnover thus provides wide-ranging correlations that are intensively studied, extensively published and documented. No other bio-event associated with the TJB can claim such investigation, and no bio-event is comparable to the ammonite turnover to provide a globally correlateable criterion for boundary definition. Using the LO of Psiloceras tilmanni as to define the TJB thus has these advantages: 1. it maintains longstanding tradition of placing the boundary so that all smooth-shelled psiloceratids are Jurassic; 2. it is a boundary above all bio-events traditionally considered Triassic (Fig. 1); 3. it provides an ammonite-based definition of broad correlation potential (P. tilmanni has a distribution from Nevada to Chile); 4. it places the boundary close to (just above) other marker events that can be used to identify the TJB in sections that lack ammonites (Fig. 1). The LO of P. tilmanni thus defines a TJB of optimal correlation potential.

12

The IBA self-extracting cyclotron project

Kleeven W., Lucas S., Delvaux J., Swoboda F., Zaremba S., Beeckman W., Vandeplassche D., Abs M.

Nukleonika

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2003

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Vol. 48,suppl.2

59-67

EN

The self-extracting cyclotron is a high-intensity 14 MeV H+ machine for isotope production. There is no electrostatic deflector. Extraction is achieved with a special shaping of the magnetic field. There are two long poles and two short poles, both with an elliptical gap profile; this provides a steep fall off of the magnetic field at the pole radii. An extraction groove is machined in the iron of one of the longer poles. First harmonic coils create a large orbit separation at the entrance of the extraction path and extract the beam. The machine is presently installed in the industrial isotope production site where the final commissioning and tests took place. Beams of more than 1.5 mA have been extracted and transported. Further development is ongoing in order to increase the current on target to at least 2 mA in the coming months. Commercial isotope production will start in the course of this year. The concept of the machine is explained and the layout of the machine and beam lines is presented. Results of orbit calculations and central region optimizations are given. Results of the measurement of extracted beam shapes and emittances are given. The progress and present status of the project are discussed.