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Veizer J.,Carleton University | Prokoph A.,Speedstat
Earth-Science Reviews | Year: 2015

The temperature of ancient oceans is an important constraint for understanding the climate history of our planet. The classical oxygen isotope paleothermometry on fossil shells, while very proficient when applied to the younger (Cenozoic) portion of the geologic record, is believed to yield only unreliable results for the Phanerozoic "deep time", either because the empirically well documented secular trend to more negative δ18O values with increasing age was generated by post-depositional recrystallization processes or, if primary, implies ecologically unpalatable hot early oceans. Here we present a compilation of δ18O measurements for 58,532 low-Mg calcite marine shells that cover almost the entire Phanerozoic eon, argue that the secular decline of about -6‰ is primary, propose that it reflects the changing oxygen isotopic composition of sea water, and define a new baseline trend for δ18O of paleo-sea water; the latter providing a new template for calculation of ambient habitat temperatures of fossil specimens. The resulting pattern for fossil taxa (foraminifera, brachiopods, belemnites and bivalves) mimics their modern counterparts in temperature ranges and modes. This conceptual framework enables application of actualistic concepts to ambient habitat temperatures of fossils and provides us with a long overdue tool for interpretation of "deep time" geologic history. © 2015 Elsevier B.V.. Source

Prokoph A.,Speedstat | Prokoph A.,Carleton University | Babalola L.O.,Carleton University | Babalola L.O.,King Fahd University of Petroleum and Minerals | And 3 more authors.
Cretaceous Research | Year: 2013

The Cenomanian-Turonian boundary was characterized by distinctive positive carbon isotope excursions that were related to the formation of widespread oceanic anoxia. High-resolution geochemical proxies (TOC, CaCO3, δ13Corg, and δ13Ccarb) obtained from bulk rock, planktic foraminifers, and inoceramids from four marine marlstone-dominated stratigraphic sections in the Western Canada Sedimentary Basin (WCSB) were used to establish a regional carbon isotope stratigraphic framework and to investigate paleoenvironmental variability in four different depositional settings. Compared to background δ13Corg, (<-27‰) and δ13Ccarb (<2‰) values which were correlative to stable isotope excursions during Oceanic Anoxic Event (OAE) II worldwide, the δ13Corg (>24‰), and δ13Ccarb (>4‰) derived from inoceramid prisms in the studied sections within WCSB, were elevated during the Late Cenomanian-Early Turonian. During this interval, TOC and CaCO3 values which increased sporadically to >40% and 7%, respectively, were not consistent enough to be used for stratigraphic correlations. Based on the δ13Corg excursions, two bentonite beds were regionally correlated across this portion of the Western Interior Seaway (WIS). The eruption associated with the "Red" bentonite occurred approximately coeval with the maximum δ13Corg-excursion during OAE II in the Neocardioceras juddii Zone, whereas the "Blue" bentonite coincides with the termination of OAE II in the latest Watinoceras devonense zone. During the Late Cenomanian-Early Turonian in the WCSB, benthic foraminifers were sparse or totally absent, indicating the existence of fully anoxic bottom-water conditions. Planktic foraminifera were common in the well-oxygenated surface waters. A benthic oxic zone characterized by several agglutinated species occurs in the eastern part of the WSCB at the beginning of OAE II in the Sciponoceras gracile zone. The termination of the OAE II in the WCSB coincides with the first occurrence of small ammonites (Subprionocyclus sp.) in the western part of the basin. © 2013 Elsevier Ltd. Source

Adamowski J.,McGill University | Prokoph A.,Speedstat
Journal of Hydrology | Year: 2013

Due to a variety of commercial and residential activities, large metropolitan areas in mid-to-high latitudinal ranges are experiencing rising air temperatures compared to their surrounding rural areas. This study investigated how this urban heat island effect (UHIE) may influence the streamflow of rivers crossing large urban areas on annual and multi-decadal time-scales. In order to detect, link, and quantify differences in meteorological and streamflow patterns between rural and large urban areas, this study developed a methodology based on the continuous wavelet transform (CWT), cross-wavelet transform (XWT), linear regression, as well as the Mann-Kendall (MK) test. A case study was carried out for the city of Ottawa, Canada as the metropolitan centre, along with three surrounding rural locations (Angers, Arnprior, Russell), with pristine rivers crossing these locations. From roughly 1970 to 2000, air temperature in Ottawa increased at a rate exceeding 0.035. °C/year, while parallel changes in rural areas were relatively stable, and varied by less than 0.025. °C/year. The urban warming that occurred during these decades was accompanied by a significant drop in the amplitude of annual temperatures (i.e. warmer winters). Precipitation in both urban and rural areas showed no significant trends, although the variability in the precipitation amount decreased in both settings. Concurrently, streamflow showed decreasing trends in both urban and rural areas. Annual amplitudes in urban streamflow (Rideau River through Ottawa, ON) correlated positively with annual air temperature amplitudes (i.e., less severe annual flooding with a decreasing winter/summer temperature contrast), whereas such a relationship was not apparent for the rural stations. Moreover, the timing of the annual daily minimum temperature cycle correlated significantly with the streamflow pattern in the urban area, i.e., early annual warming corresponded to earlier annual streamflow maxima. The precipitation pattern (i.e. distribution of rain and snowfall over time) significantly influenced the annual and long term streamflow pattern, but this influence differed little between urban and rural areas. It was also determined that the warming from the urban heat island effect, especially during winter months, was found to perhaps reduce the severity of the annual spring flood event in mid-to-high latitudinal continental settings. © 2013 Elsevier B.V. Source

Prokoph A.,Speedstat | Puetz S.J.,Progressive Science Institute
Mathematical Geosciences | Year: 2015

Period-tripling is a common but rarely studied feature of natural processes. Its detection in long-term geological events is often restricted by poor preservation, inadequate time-resolution, and insufficient record lengths. This work includes an analysis of the highest-resolution and most complete multi-billion year sequence of geological and paleobiological records to determine the hierarchy of nonlinear (fractal) and periodic components. Using wavelet, spectral, and nonlinear analysis methods, a similar set of cycles emerged from these different records. The analyses indicate that the period-tripling pattern persists in geological and paleobiological events on time-scales of $$\sim$$∼30 to $$\sim$$∼1600 million years. The observed quasi-periodic tripling pattern could theoretically arise similar to bifurcations in a logistic map with a growth potential parameter of $$\mu =3.83$$μ=3.83. Many of the period-tripled cycles exhibit half-cycle counter-parts. Most likely, the half-cycles developed from oscillations involving low-dynamic states versus the high-dynamic states of the full-cycles. Moreover, the period-tripling process contributes to fractal clustering of geological and biological events such as the eruptions of large igneous provinces. This is verified with the box-counting method for a model with a single dominant variable (a one-dimensional vector of $$d=0.815$$d=0.815), for observational spans of less than 180 million years, and for a Cantor set model with a box dimension of ln(6)/ln(9). © 2015, International Association for Mathematical Geosciences. Source