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101.
Quantifying the influence of sill intrusion on the thermal evolution of organic‐rich sedimentary rocks in nonvolcanic passive margins: an example from ODP 210‐1276, offshore Newfoundland,Canada 下载免费PDF全文
Alexander Peace Ken McCaffrey Jonathan Imber Richard Hobbs Jeroen van Hunen Keith Gerdes 《Basin Research》2017,29(3):249-265
Intrusive magmatism is an integral and understudied component in both volcanic and nonvolcanic passive margins. Here, we investigate the thermal effects of widespread (ca. 20 000 km2) intrusive magmatism on the thermal evolution of organic‐rich sedimentary rocks on the nonvolcanic Newfoundland passive margin. ODP 210‐1276 (45.41°N, 44.79°W) intersects two sills: an older, upper sill and a younger, lower sill that are believed to correspond to the high amplitude ‘U‐reflector’ observed across the Newfoundland Basin. A compilation of previous work collectively provides; (1) emplacement depth constraints, (2) vitrinite reflectance data and (3) 40Ar/39Ar dates. Collectively, these data sets provide a unique opportunity to model the conductive cooling of the sills and how they affect thermal maturity of the sedimentary sequence. A finite differences method was used to model the cooling of the sills, with the model outputs then being entered into the EASY%Ro vitrinite reflectance model. The modelled maturation profile for ODP 210‐1276 shows a significant but localized effect on sediment maturity as a result of the intrusions. Our results suggest that even on nonvolcanic margins, intrusive magmatism can significantly influence the thermal evolution in the vicinity of igneous intrusions. In addition, the presence of widespread sills on nonvolcanic passive margins such as offshore Newfoundland may be indicative of regional‐scale thermal perturbations that should be considered in source rock maturation studies. 相似文献
102.
Yaping Zhou Ken C. Rutledge Analytical Service & Material Inc Hampton VA USA Thomas P. Charlock Atmospheric Sciences Division NASA Langley Research Center Hampton VA USA Norman G. Loeb Seiji Kato Hampton University Hampton VA USA 《大气科学进展》2001,(5)
l. IntroductionThe cIassicaI definition of bi--directional reflectance--distribution function (BRDF) is aderivative, distribution function, relatlng the irradiance incident from one given direction tolts contribution to the radiance renected in another direct1on (N1codemus et al., l977).f r (0,, rp,; 0,, rp, )= dL, (0,, P,; 0,, 9,; E, )/ dE, (0,, 9,) [sr-- 1 ], (l)where 0 (zenith angle) and 9 (azimuth angle) together indicate a direction, the subscr1pt i indi-cates quantities associated wi… 相似文献
103.
This work develops the theory of measuring fracture frequency with curved scanlines, as a direct development of work done
by others on straight scanlines. Various possible shapes for curved scanlines range between triangular and rectangular, with
circular as a reasonable preliminary selection. The discrepancy among different selections decreases with increasing roughness
amplitude of the scanline. Analytic solutions for average fracture frequency are given for circular scanlines through single
and multiple fracture sets. Results for single fracture sets are plotted. The analytic solution for the general situation
of any shape scanline through multiple fracture sets is given. Analytic solutions are given and plotted for circular scanlines
through a fracture fabric ellipsoid. A circular scanline spanning 180 degrees yields a global fracture frequency of statistical
significance.
This work was carried out under U.S. Department of Energy Contract No. DEAC03-76SF00098 for the Director, Office of Civilian
Radioactive Waste Management, Office of External Relations, and was administered by the Nevada Operations Office, U.S. Department
of Energy. This work also was supported partially by the Power Reactor and Nuclear Fuel Development Corporation of Japan. 相似文献
104.
Suzanne Lesage Richard E. Jackson Mark Priddle Paul Beck Ken G. Raven 《Ground Water Monitoring & Remediation》1991,11(1):151-159
The objective of this study was to assess the possible impact of deep well disposal operations, conducted between 1958 and 1974, on the ground water quality in a shallow fresh water aquifer beneath Sarnia, Ontario, Canada. Because of the breakout of formation fluids in Sarnia and Port Huron, Michigan, in the early 1970s, it had been hypothesized that liquid waste from the disposal zone in bedrock had leaked through numerous abandoned oil, gas, and salt wells in the area up to the shallow fresh water aquifer and from there to the surface.
A monitoring well network of 29 5cm (2 inch) diameter piezometers was established in the thin sand and shale aquifer system, which exists between 30 and 70m (100 and 230 feet) below ground surface. In addition, a 300m (1000 foot) deep borehole was drilled and instrumented with a Westbay multilevel casing, which permitted sampling of the disposal zone.
Ground water samples from the shallow monitoring wells and the Westbay multilevel casing were analyzed for volatiles by GC/MS. Those volatile aromatics that were conspicuously present in the deep disposal zone, e.g., ethyl toluenes and trimethyl benzene, were not detected in the shallow monitoring wells. Thus, if contaminants from the disposal zone did indeed migrate to the shallow aquifer, contamination was not widespread and probably consisted mostly of displaced chloride-rich formation waters. 相似文献
A monitoring well network of 29 5cm (2 inch) diameter piezometers was established in the thin sand and shale aquifer system, which exists between 30 and 70m (100 and 230 feet) below ground surface. In addition, a 300m (1000 foot) deep borehole was drilled and instrumented with a Westbay multilevel casing, which permitted sampling of the disposal zone.
Ground water samples from the shallow monitoring wells and the Westbay multilevel casing were analyzed for volatiles by GC/MS. Those volatile aromatics that were conspicuously present in the deep disposal zone, e.g., ethyl toluenes and trimethyl benzene, were not detected in the shallow monitoring wells. Thus, if contaminants from the disposal zone did indeed migrate to the shallow aquifer, contamination was not widespread and probably consisted mostly of displaced chloride-rich formation waters. 相似文献
105.
106.
107.
Despite their potential impact, trends in thunderstorm occurrence in Canada have not received scientific scrutiny, one of the reasons for this likely being lack of data availability. A previous study showed thunderstorm observations at eight staffed weather stations in southern Ontario, Canada, to be accurate for distances within 10?km. We used hourly thunderstorm data from these stations and one additional station to determine whether a trend exists in the thunderstorm record in this region. A Mann-Kendall test and Theil-Sen approach determined that although some stations do have trends in number of thunderstorm hours per year over this time, a consistent increase in the number of thunderstorms that might be expected in a warming climate is not seen. Daily precipitation totals and maximum wind gust speeds were also used as proxies for thunderstorm intensity, neither of which confirmed an increase in the intensity of thunderstorms at these sites over the time period. 相似文献
108.
We use recently acquired magnetic and SeaBeam bathymetric data to examine the spreading rates and plate boundary geometry of the Mid-Atlantic Ridge 30°–36° S. Using a statistically rigorous estimation of rotation poles we develop a precise spreading history of the African—South American plate boundary. The total opening rate for 1–4.23 Myr (Plio-Pleistocene) is nearly constant at 32.3 ± 1 km Myr–1. The spreading rate apparently is faster in the Late Miocene (7.3-5.3 Myr), though this may reflect inaccuracies in the geomagnetic time scale. The rotation poles enable a plate boundary reconstruction with an accuracy of 2–3 km. The reconstructions also show that the plate boundary geometry underwent several changes since the late Miocene including the growth of one ridge segment from 40 to 105 km in length, and the reorientation of another ridge segment which has spread obliquely from 7 to 1 Myr. Pole calculations using both right- and left-stepping fracture zones show an offset of 1–2 km between the deepest, most linear part of a fracture zone trough and the former plate boundary location. The high-resolution plate kinematics suggests that the plate boundary, as a whole, evolves 2-dimensionally as prescribed by rigid plates. On a local scale, asymmetric accretion, asymmetric extension, small lateral ridge jumps (< 3 km), and intra-segment propagation result in minor plate boundary adjustments and deformation to the rigid plates. 相似文献
109.
Yukio Fujinawa Yoshinobu Tsuji Isao Watabe Ken Sasaki Masao Nomoto Toshiaki Hara Yoshito Tsuji 《Journal of Oceanography》1980,36(5):253-258
The results of laboratory and field experiments on a CTD measuring unit attached to a controllable towed body is described. It was verified that the three-dimensional distribution of salinity and temperature could be observed with sufficient accuracy (to 0.03 in salinity and to 0.01°C in temperature if proper correction is adopted) while cruising at up to 4 knots. A double integrated A/D converter is used to compensate for effects of extraneous environmental changes. 相似文献
110.
Phytoplankton distribution and its relationship to water masses were investigated in the East China Sea from February 15 to March 10, 1993. Diatoms, dinoflagellates and coccolithophorids were examined by the Utermöhl method. Two distinct phytoplankton assemblages were identified: a shelf and oceanic assemblage. The shelf community was characterized by a high abundance of diatoms, particularly, a benthic diatomParalia sulcata, and the oceanic community by numerical dominance of coccolithophorids and occurrence of surface warm-water species of diatoms. A boundary of both communities was located at the shelf edge that coincided with the shelf side of a Kuroshio front.P. sulcata was the most dominant in the inner shelf area throughout the water column. The occurrence of this species near the surface was considered to be a good indicator of the enhanced vertical mixing driven by winter monsoon. The species survives under extremely low light intensity near the bottom during the stratified periods in summer. During the winter time when light condition at the bottom becomes most unfavorable, resuspension and upward traveling of the species due to enhanced vertical mixing seem to be advantageous to acquire suitable light condition. Because of its predominance, possible importance ofP. sulcata is suggested in material cycling on the shelf, particularly near the bottom. 相似文献