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1

The Jurassic succession at Lisadele Lake (Tulsequah map area, British Columbia, Canada) and its bearing on the tectonic evolution of the Stikine terrane

Shirmohammad F., Smith P., Anderson R., McNicoll V.

Volumina Jurassica

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2011

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Vol. 9, no. 1

43-60

EN

Jurassic rocks in the central Tulsequah map area include conglomerates and interbedded fossiliferous finer clastics of the Takwahoni Formation (Laberge Group) which unconformably overlie Triassic rocks. Ammonite collections document the Pliensbachian, Toarcian and Bajocian stages. We refine the age and provenance of episodes of coarse clastic input and confirm the progressive change of dominant clast lithology from reworked sedimentary rocks above the Triassic-Jurassic unconformity to volcanic, plutonic and then metamorphic clasts in the Upper Toarcian. The uppermost coarse clastic unit is a Bajocian chert-pebble conglomerate which, along with the immediately underlying black mudstone, we include in the Bowser Lake Group. Together with regional correlations, this confirms that the age of the basal part of the Bowser Lake Group is diachronous, younging southwards into Stikinia. Sandstone petrofacies trends and changes in conglomerate clast composition indicate arc uplift and dissection followed by Middle Jurassic orogen recycling. The isotopic ages of detrital zircons and granite clasts compared with the biochronologically constrained ages of the enclosing strata suggests that processes of intrusion, arc uplift, unroofing, and clastic deposition during the Early Jurassic occurred over intervals of significantly less than five million years.

2

The Pliensbachian/Toarcian boundary in Canada: ammonite succession and correlations

Macchioni F., Palfy J., Smith P.

Volumina Jurassica

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2006

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Vol. 4, no. 1

182-182

EN

The Pliensbachian-Toarcian transition in North America is best typified by the Queen Charlotte Island ammonite succession where 3 assemblages are recognized, all of which include representatives of Lioceratoides, Protogrammoceras and Tiltoniceras. The lower assemblage also includes Fanninoceras, Amaltheus and Arieticeras, and is placed in the Pliensbachian (Carlottense Zone). The upper assemblage also includes the first occurrences of Dactylioceras and is placed in the Toarcian (Kanense Zone). The correlation of the intermediate assemblage is uncertain and it was initially placed in the Pliensbachian because it occurred beneath Dactylioceras and above Amaltheus. However, Pleuroceras that characterizes the northwest European uppermost Pliensbachian does not occur in British Columbia and it is also questionable whether the incoming of the genus Dactylioceras can be used as a means of correlation with the basal Toarcian (Tenuicostatum Zone) of northwest Europe. Consequently, it has been difficult to confidently correlate the Pliensbachian-Toarcian transition as defined in North America with the boundary as defined in northwest Europe. Light is being shed on this problem by recent work on faunas from the Laberge Group in the Yukon Territory and the Spatsizi Formation (Hazelton Group) in northcentral British Columbia. As has often been noted, Canadian sequences show stronger affinities with Mediterranean successions rather than the Boreal successions of northwest Europe. In addition to representatives of Fontanelliceras, Neolioceratoides, Canavaria, Bouleiceras and Tauromeniceras, there are several new occurrences of Dactylioceras. The Tethyan Dactylioceras cf. simplex occurs low in the Kanense Zone and suggests a correlation with the D. simplex horizon of the basal Polymorphum Zone in the Mediterranean area, which predates the basal Tenuicostatum Zone of NW Europe.

3

Early Hettangian ammonites and radiolarians from the Queen Charlotte Islands (British Columbia, Canada) and their bearing on the definition of the Triassic/Jurassic boundary

Longridge L., Carter E., Smith P., Tipper H.

Volumina Jurassica

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2006

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Vol. 4, no. 1

290-290

EN

The extinction that marks the Triassic/Jurassic boundary (T/J boundary) is one of the so-called "big five" that punctuate the Phanerozoic. Two sequences spanning the boundary occur in the Queen Charlotte Islands (QCI) of British Columbia; one is located at Kennecott Point on Graham Island (section I), the other on the southeastern shore of Kunga Island (section III). A second section at Kennecott Point contains fossils of Early Hettangian age only (section II). Eleven ammonite taxa are present in the Lower Hettangian sections of the QCI. Ammonite faunas indicate an Early Hettangian age for the upper portion of section I and permit correlation of the upper portion of section II with the middle Lower Hettangian Minutum Zone. Section III contains moderately diverse Early Hettangian ammonites that allow correlation of the lower portion of the section with the Minutum and Pacificum zones and the upper portion with the upper Lower Hettangian Polymorphum Zone. Lower Hettangian radiolarians from the Canoptum merum Zone are present in all three sections; a few Upper Rhaetian holdovers from the Globolaxtorum tozeri Zone are also present in sections I and II. The T/J boundary radiolarian faunas correlate closely with those in the Inuyama area of Japan indicating that radiolarians were globally distributed at that time. Although ammonite preservation is poor, radiolarian preservation is excellent and the turnover combined with continuous deposition and lack of facies changes over this interval marks the most distinct boundary level currently recognized worldwide. Section I has also produced a carbon isotope curve which records a prolonged negative excursion spanning the T/J boundary while section III has provided a U-Pb date of 199.6±0.3 Ma which constrains the boundary. The latter section has already been proposed as a potential basal Hettangian Global Stratotype Section and Point (GSSP). Although all three QCI sections lack ammonites from the basal Hettangian Spelae ammonite Zone, sections I and III have both yielded earliest Hettangian radiolarian collections which contain Rhaetian holdovers suggesting an approximate correlation of the lower portion of these sections with the Spelae Zone. A section in New York Canyon, Nevada has also been proposed as a potential GSSP. This section provides a virtually complete ammonoid succession but lacks geochronology and microfossils. In essence, the sections at Kunga Island and New York Canyon are complementary. Close correlations between the two sections are possible using ammonite faunas as well as the negative carbon isotope anomalies which span the T/J boundary in Nevada and at Kennecott Point. We suggest the section from Nevada be designated as holostratotype (and datum) for the basal Hettangian and the QCI section be designated as a parastratotype to improve recognition of this interval.

4

A "counterweight mechanism" in Hettangian ammonites?

Longridge L., Smith P.

Volumina Jurassica

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2006

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Vol. 4, no. 1

239-239

EN

In most ammonites the siphuncle runs ventrally down the centre of the shell. However, many Hettangian taxa have a siphuncle that is displaced from the midline of the venter accompanied by an asymmetric septal suture line. The ventral lobe is shifted to one side of the whorl where the suture becomes simplified. The ammonites almost became extinct at the end of the Triassic and a single group became the rootstock of the subsequent adaptive radiation. The offset siphuncle is already prevalent in several of the earliest Hettangian genera and by the Late Hettangian, it is widespread throughout two of the three superfamilies. The displacement of the tissue and blood filled siphuncle would have affected the position of the shell’s centre of mass. In order for the ammonite animal to remain vertical in the water column, a "counterweight" system may have been developed. We use computer modeling and data on shell structure to examine this question.

5

EU environment regulation and their impact on competitiveness of European lead and zinc industry in the EU 10

Kulczycka J., Smith P.

Gospodarka Surowcami Mineralnymi

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2004

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T. 20, z. 4

127-144

EN

With the enlargement process, mining companies in the new member countries will have to reach EU environmental standards by implementing European legislation, and have a greater awareness of pollution prevention and control as well as waste management. The most important EU legal regulations, which influence zinc and lead producers in the new EU countries are: 1) the European Directive on Pollution Prevention 96/61/EC of 24th September 1996 (IPPC): "Integrated Pollution Prevention and Control (IPPC)", 2) a draft proposal for a new Batteries Directive (91/157/eec) - adopted the European Commission in November 2003, i.e. it is a revision of the Council Directive of 18 march 1991 on Batteries and Accumulators, 3) a Proposal of EU Directive on the Management of the Waste from Extractive Industries, which was officialy published on June 2, 2003, 4) a EU communication (COM (2003) 572) entitled "Towards a thematic Strategy on the Sustainable Use of Natural Resources" - officially published in October 2003. The applicant countries were expected to transpose all existing Community environmental law into their national legislation, and this is taking considerable effort. The influence of new laws influence to the behavior of companies, but its impact on their competitiveness, particulary in the mining sector in EU new members.

PL

W referacie omówiono założenia propozycji nowych dyrektyw i komunikatów tworzonych w Unii Europejskiej, które - jeżeli zostaną wdrożone - będą miały znaczący wpływ na działalność krajowych podmiotów górniczych. Analizę prowadzono na przykładzie przemysłu cynku i ołowiu w krajach UE, w tym w Polsce. Wykazano zarówno znaczenie polskiego wydobycia na tle krajów UE i świata, jak i przeanalizowano istniejące koszty produkcji i koszty zarządzania odpadami oraz przedstawiono dodatkowe zobowiązania wprowadzonych w wybranych kopalniach cynku i ołowiu rozwiązań w zakresie gospodarki odpadami (np. zarząd kopalni Lisheen w Irlandii, przed uzyskaniem pozwolenia na rozpoczęcia wydobycia, musiał zapewnić, że 51% odpadów będzie mieszanych z cementem i lokowanych pod ziemią).