An extensive erosion surface of a strongly deformed limestone bed in the Gushan and Chaomidian formations (late Middle Cambrian to Furongian), Shandong Province,China: Sequence–stratigraphic implications     

Jitao Chen  S.K. Chough  Zuozhen Han  Jeong-Hyun Lee 《Sedimentary Geology》2011,233(1-4):129-149

In order to understand sequence development and sea-level fluctuations during the late Middle Cambrian to early Furongian on the North China epeiric platform, the present study focuses on a unique, subtle erosion surface of an extensive (approx. 100 km), strongly deformed limestone bed in the uppermost part of the Gushan Formation, Shandong Province, China. The Gushan Formation and the overlying Chaomidian Formation consist mainly of shales and a variety of carbonates that were deposited in subtidal environments (e.g., deep subtidal, shallow subtidal, shoreface/shoal, subtidal microbial flat, and restricted platform interior). Three third-order depositional sequences (S1–3) are identified, each of which comprises a thin transgressive systems tract (TST) and a relatively thick highstand systems tract (HST). Each sequence is bounded by a drowning unconformity (SB1), a subaerial unconformity (SB2), or a surface of submarine erosion (SB3). The upper sequence boundary (SB2) of sequence 1 (S1) is represented by a subtle erosion surface of an extensive, deformed limestone bed with a wide variety of soft-sediment deformation structures (e.g., lime mudstone breccias, chaotic wacke-packstone laminae and fragments, homogenized oolites, and clastic dykes), and is overlain by small sporadic microbial buildups and an extensive bioclastic grainstone bed. The deformed limestone was formed during early diagenesis by differential deformation processes (brecciation, liquefaction/fluidization, and injection) which were most likely induced by pore-water overpressure during the period of rapid sea-level fall. Despite the lack of subaerial exposure features (e.g., paleokarst, paleosol, etc.), the characteristics of the erosion surface (cutting well-lithified sediment below), the missing of a significant geological record (the Prochuangia biozone), and the worldwide correlatable positive carbon isotope excursion collectively indicate that the erosion surface developed under conditions of subaerial exposure after contemporaneous marine cementation of the deformed sediment. The missing of the Prochuangia biozone is most likely due to non-deposition at a subaerial hiatal surface. The erosion surface was submerged as a result of subsequent rise in sea level, where sporadic microbial buildups formed under suitable conditions. Freshly deposited, winnowed, shell-dominated transgressive lag deposits (containing Chuangia trilobite fragments, brachiopod shells, and abundant glauconite grains) formed with continued rise in sea level, which became, in turn, overlain by shale-dominated facies. The unique combination of the subtle erosion surface (sensu stricto a subaerial unconformity) and the underlying deformed limestone bed provides an important criterion for recognizing the subtle changes in relative sea level on shallow epeiric platforms.  相似文献   

Carbon isotope composition of Upper Cambrian to Lower Ordovician carbonate in Korea,and its bearing on the Cambrian–Ordovician boundary and Lower Ordovician paleoceanography     

Sung Kyung Hong  Yong Il Lee  So Yeong Jeong 《Journal of Asian Earth Sciences》2011,40(1):252-260

This study presents an example of locating Cambrian–Ordovician boundary in the lower Paleozoic carbonate succession in Korea using carbon isotope stratigraphy. The Yeongweol Unit of the lower Paleozoic Joseon Supergroup comprises the Upper Cambrian Wagok Formation and the Lower Ordovician Mungok Formation in the Cambrian–Ordovician transition interval. Conventionally, the boundary was placed at the lithostratigraphic boundary between the two formations. This study reveals that the boundary is positioned in the basal part of the Mungok Formation based on the carbon isotope stratigraphy coupled with biostratigraphic information of conodont and trilobite faunas. The δ¹³C curve of the Lower Ordovician Mungok Formation shows a similar trend to that of the coeval stratigraphic interval of Argentine Precordillera (Buggisch et al., 2003), suggesting that the δ¹³C curve of the Mungok Formation reflects the Early Ordovician global carbon cycle.  相似文献   

Investigation of CO₂ behavior and study on design of optimal injection into Gorae-V aquifer     

W. M. Sung  Y. S. Lee  K. H. Kim  Y. H. Jang  J. H. Lee  I. H. Yoo 《Environmental Earth Sciences》2011,64(7):1815-1821

This study presents the Bottom-hole pressure (BHP) behavior with different wettabilities and the optimal design scheme to effectively inject CO₂ into the Gorae-V aquifer. As a result, the injection rate and injectivity were increased as the wettability condition became more water-wet. However, the more wettability condition becomes water-wet, the more the ultimate CO₂ injection volume decreases. When the injectivity was 346 ton/day/Mpa at the Gorae-V aquifer, the aquifer can sustain CO₂ injection at a rate of 2,425 tons per day over this time period. A design for a complete CCS system was developed based on the existing off-shore pipeline in combination with new on-shore CO₂ transport infrastructure, and a pressure of 12.8 MPa is required at the CO₂ source to maintain this injection rate.  相似文献   

Numerical simulation of nearshore circulation on field topography under random wave environment     

Junwoo Choi  Sung Bum Yoon 《Coastal Engineering》2011

In order to investigate surf zone hydrodynamics through two-dimensional numerical simulations of nearshore circulation under random wave environment, a nearshore circulation model, SHORECIRC, and a random wave model, SWAN, were combined and utilized. Using this combined model, a numerical simulation of the October 2, 1997 SandyDuck field experiment was performed. For this simulation, field topography and an input offshore spectrum were constructed using observed data sets synchronized with the experiment. The wave-breaking model in SWAN was modified by using breaker parameters varied according to bottom slope. The simulation results were compared with the experimental data, which revealed a well-developed longshore current, as well as with results using other combinations which were SHORECIRC and its original monochromatic wave-driver, and SHORECIRC and the default of SWAN. The results from the novel combined model agreed well with the experimental data. The results of the present simulation also indicate that alongshore field topography influences shear fluctuation of longshore currents.  相似文献   

Tracing origins of sewage and organic matter using dissolved sterols in Masan and Haengam Bay,Korea     

Hyo Jin Lee  Sang Hee Hong  Moonkoo Kim  Sung Yong Ha  Soon Mo An  Won Joon Shim 《Ocean Science Journal》2011,46(2):95-103

Masan and Haengam Bays in Korea are highly polluted and semi-enclosed. Domestic and industrial effluents are directly or indirectly discharged into the bays through sewage treatment plants (STP) and creeks. In this study, 15 dissolved sterol compounds were determined in order to understand their sources and relative contribution. Freshwater samples were taken from 13 creeks and at two STP sites on a monthly basis. Total dissolved sterol concentrations ranged from 993 to 4158 ng/L. The concentrations of sterols in winter were higher than in summer. Among the sterols analyzed, cholesterol, β-sitosterol, coprostanol and cholestanone were major compounds in creek water. Seawater samples were concurrently collected at 21 stations in Masan Bay. Total sterol concentrations ranged 118–6,956 ng/L. Inner bay showed high concentrations of sterols in summer, while outer bay showed high sterol concentrations in winter. Among the sterols, cholesterol, β-sitosterol and brassicasterol were major compounds in seawater. In order to examine the contribution of urban sewage, the concentration of coprostanol and fecal sterol ratios were calculated. Most of the creek water, inner bay and near STP outlet samples were affected by sewage. Terrestrial organic matters accounted for a high proportion of dissolved organic matter origin. Fecal origins were relatively high in the inner bay areas and in the STP outlet, while sterols of marine origin were high in the outer bay areas.  相似文献   

FT-IR measurements of cold C₃H₈ cross sections at 7–15 μm for Titan atmosphere     

Keeyoon Sung  Geoffrey C. Toon  Arlan W. Mantz  Mary Ann H. Smith 《Icarus》2013

We present absorption cross sections of propane (C₃H₈) at temperatures from 145 K to 297 K in the 690–1550 cm⁻¹ region. Pure and N₂-broadened spectra were measured at pressures from 3 Torr to 742 Torr using a Bruker IFS125 FT-IR spectrometer at JPL. The gas absorption cell, developed at Connecticut College, was cooled by a closed-cycle helium refrigerator. The cross sections were measured and compiled for individual spectra recorded at various experimental conditions covering the planetary atmosphere and Titan. In addition to the cross sections, a propane pseudoline list with a frequency grid of 0.005 cm⁻¹, was fitted to the 34 laboratory spectra. Line intensities and lower state energies were retrieved for each line, assuming a constant width. Validation tests showed that the pseudoline list reproduces discrete absorption features and continuum, the latter contributed by numerous weak and hot band features, in most of the observed spectra within 3%. Based on the pseudoline list, the total intensity in the 690–1550 cm⁻¹ region was determined to be 52.93 (±3%) × 10⁻¹⁹ cm⁻¹/(molecule cm⁻²) at 296 K; this value is within 3% of the average from four earlier studies. Finally, the merit of the pseudoline approach is addressed for heavy polyatomic molecules in support of spectroscopic observation of atmospheres of Titan and other planets. The cold cross sections will be submitted to the HITRAN database (hitran.harvard.edu), and the list of C₃H₈ pseudolines will be available from a MK-IV website of JPL (http://mark4sun.jpl.nasa.gov/data/spec/Pseudo).  相似文献