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TitleNd isotope constraints on ocean circulation, paleoclimate, and continental drainage during the Jurassic breakup of Pangea
AuthorDera, G; Prunier, J; Smith, P L; Haggart, J W; Popov, E; Guzhov, A; Rogov, M; Delsate, D; Thies, D; Cuny, G; Pucéat, E; Charbonnier, G; Bayon, G
SourceGondwana Research vol. 27, 2015 p. 1599-1615, https://doi.org/10.1016/j.gr.2014.02.006
Year2015
Alt SeriesEarth Sciences Sector, Contribution Series 20130165
PublisherElsevier
Documentserial
Lang.English; English
Mediaon-line; digital
File formatpdf
ProvinceCanada; British Columbia; Alberta; Manitoba; New Brunswick; Newfoundland and Labrador; Northwest Territories; Nova Scotia; Nunavut; Ontario; Prince Edward Island; Quebec; Saskatchewan; Yukon; British Columbia; Alberta; Saskatchewan; Manitoba; Ontario; Quebec; New Brunswick; Nova Scotia; Prince Edward Island; Newfoundland and Labrador; Northwest Territories; Yukon; Nunavut
NTS1; 2; 3; 10; 11; 12; 13; 14; 15; 16; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 52; 53; 54; 55; 56; 57; 58; 59; 62; 63; 64; 65; 66; 67; 68; 69; 72; 73; 74; 75; 76; 77; 78; 79; 82; 83; 84; 85; 86; 87; 88; 89; 92; 93; 94; 95; 96; 97; 98; 99; 102; 103; 104; 105; 106; 107; 114O; 114P; 115; 116; 117; 120; 340; 560
AreaFrance; Germany; Denmark; Russian Federation; United Kingdom; Luxembourg; United States; Mexico
Lat/Long WENS180.0000 -180.0000 90.0000 -90.0000
Subjectsmarine geology; geochemistry; isotopic studies; neodymium; paleoclimates; paleodrainage; paleoenvironment; sea water geochemistry; Toarcian; Aalenian; Bathonian; Callovian; Oxfordian; Tithonian; water temperature; provenance; Pangea; Gondwana; Tethys Ocean; Panthalassa Ocean; Jurassic
ProgramFrontier basin analysis, Geoscience for New Energy Supply (GNES)
AbstractThe breakup of Pangea and onset of growth of the Pacific plate led to several paleoenvironmental feedbacks, which radically affected paleoclimate and ocean chemistry during the Jurassic. Overall, this period was characterized by intense volcanic degassing from large igneous provinces and circum-Panthalassan arcs, new oceanic circulation patterns, and changes in heat and humidity transports affecting continental weathering. Few studies, however, have attempted to unravel the global interactions linking these processes over the long-term. In this paper, we address this question by documenting the global changes in continental drainage and surface oceanic circulation for the whole Jurassic period. For this purpose, we present 53 new neodymium isotope values (epsilon-Nd(t)) measured on well-dated fossil fish teeth, ichthyosaur bones, phosphatized nodules, phosphatized ooids, and clastic sediments from Europe, western Russia, and North America.

Combined with an extensive compilation of published epsilon-Nd(t) data, our results show that the continental sources of Nd were very heterogeneous across the world. Volcanic inputs from a Jurassic equivalent of the modern Pacific Ring of Fire contributed to radiogenic epsilon-Nd(t) values (- 4 epsilon-units) in the Panthalassa Ocean. For the Tethyan Ocean, the average surface seawater signal was less radiogenic in the equatorial region (- 6.3), and gradually lower toward the epicontinental peri-Tethyan (- 7.4), western Russian (- 7.4) and Euro-Boreal seas (- 8.6). Different Nd sources contributed to this disparity, with radiogenic Nd influxes from westward Panthalassan currents or juvenile volcanic arcs in open oceanic domains, and substantial unradiogenic inputs from old Laurasian and Gondwanan shields for the NW Tethyan platforms. Overall, the epsilon-Nd(t) values of Euro-Boreal, peri-Tethyan, and western Russian waters varied quite similarly through time, in response to regional changes in oceanic circulation, paleoclimate, continental drainage, and volcanism. Three positive shifts in epsilon-Nd(t) values occurred successively in these epicontinental seas during the Pliensbachian, in the Aalenian--Bathonian interval, and in the mid-Oxfordian. The first and third events are interpreted as regional incursions of warm surface radiogenic currents from low latitudes. The Aalenian--Bathonian shift seems linked to volcanic outbursts in the NW Tethys and/or circulation of deep currents resulting from extensional events in the Hispanic Corridor and reduced influences of boreal currents crossing the Viking Corridor. In contrast, the epsilon-Nd(t) signals decreased and remained very low (< - 8) during the global warming events of the Toarcian and Late Oxfordian--Early Tithonian intervals. In these greenhouse contexts, a latitudinal expansion of humid belts could have extended the drainage pathways toward boreal Nd sources of Precambrian age and increased the supply of very unradiogenic crustal-derived inputs to seawater. Finally, a brief negative epsilon-Nd(t) excursion recorded in parallel with regional drops in seawater temperature suggests that southward circulation of cold unradiogenic Arctic waters occurred in the NW Tethys in the Callovian--Early Oxfordian. All these results show that changes in surface oceanic circulation resulting from the Pangean breakup could have regionally impacted the evolution of seawater temperatures in the NW Tethys.
Summary(Plain Language Summary, not published)
This contribution is a report that will appear in a scientific journal. The authors use concentrations of the element neodymium, which is abundant in the world's oceans, to identify the changing proportions of sediment in the oceans of the Earth during the Jurassic Period, about 200-150 million years ago, and to model the paleogeography of the Earth during this time. The study included rocks from the offshore Haida Gwaii region of British Columbia, an underexplored frontier hydrocarbon basin. The neodymium data also help to identify times of increased global anoxia, or reduced oxygen in the world's oceans, during Jurassic time. Global anoxia is often accompanied by significant buildup of organic matter in the sedimentary deposits of the oceans, which can serve as a source for petroleum and natural gas deposits. The data in the report are useful in helping to understand the development of potential oil and gas resources in Canada's west coast offshore region.
GEOSCAN ID292882