Investigation of Late-Quaternary sediments from the South Yellow Sea and the Yangtze River Delta (China)

The results of a study to determine the geochemical, mineralogical, magnetic and textural characteristics done on Late-Quaternary sediments from drill cores from the South Yellow Sea (core H106) and the Yangtze River Delta (core LA) (China) are reported. The Late-Pleistocene continental sedimentation is represented by clayey silt and hard clay layers, while the marine Holocene sediments consist mainly of clay (H106) and sand and clay layers (LA)

CLAY SEDIMENTS FROM ITALY AND CHINA

Mineralogical and textural variations in Upper Pleistocene and Holocene clay sediments from three cores taken in different depositional environments: the Venetian lagoonal littoral zone, the South Yellow Sea and the Yangtze River Delta, are reported. The compositional variations of clay layers from the three sites are attributed to major global climatic changes. Although the compositional difference of clay sediments of the three sites reflects the petrology of their different areas of provenance, the relative abundance and textural variations show a correlation with climatic-driven changes in their depositional environment. In the Venice lagoon the carbonate content decreases from cold to warm periods whereas in the Yangtze River delta and in the South Yellow Sea carbonates are absent or not significant, and the most noticeable changes are given by the total clay mineral content variations (chlorite, smectite, mixed-layer clay minerals and muscovite) and feldspar. There is a general increase in abundance of clay minerals and a decrease in feldspar content during warm periods. The cores from all three study sites have overconsolidated continentally-derived clay layers at the Pleistocenel/Holocene (ca. 10,000 BP) boundary. The overconsolidated nature of these hard clay layers is due to long subaerial exposure under a cold and dry climatic regime before the Holocene (Flandrian) transgression.PublishedOttawa, Canada3A. Ambiente Marinoope

CLAY SEDIMENTS FROM ITALY AND CHINA

Mineralogical and textural variations in Upper Pleistocene and Holocene clay sediments from three cores taken in different depositional environments: the Venetian lagoonal littoral zone, the South Yellow Sea and the Yangtze River Delta, are reported. The compositional variations of clay layers from the three sites are attributed to major global climatic changes. Although the compositional difference of clay sediments of the three sites reflects the petrology of their different areas of provenance, the relative abundance and textural variations show a correlation with climatic-driven changes in their depositional environment. In the Venice lagoon the carbonate content decreases from cold to warm periods whereas in the Yangtze River delta and in the South Yellow Sea carbonates are absent or not significant, and the most noticeable changes are given by the total clay mineral content variations (chlorite, smectite, mixed-layer clay minerals and muscovite) and feldspar. There is a general increase in abundance of clay minerals and a decrease in feldspar content during warm periods. The cores from all three study sites have overconsolidated continentally-derived clay layers at the Pleistocenel/Holocene (ca. 10,000 BP) boundary. The overconsolidated nature of these hard clay layers is due to long subaerial exposure under a cold and dry climatic regime before the Holocene (Flandrian) transgression

Investigation of Late-Quaternary sediments from the South Yellow Sea and the Yangtze River Delta (China)

The results of a study to determine the geochemical, mineralogical, magnetic and textural characteristics done on Late-Quaternary sediments from drill cores from the South Yellow Sea (core H106) and the Yangtze River Delta (core LA) (China) are reported. The Late-Pleistocene continental sedimentation is represented by clayey silt and hard clay layers, while the marine Holocene sediments consist mainly of clay (H106) and sand and clay layers (LA).PublishedQingdao, China6A. Monitoraggio ambientale, sicurezza e territorioope

CO2-Enhanced Oil Recovery Mechanism in Canadian Bakken Shale

The recovery factor in unconventional reservoirs is typically 5–10%, with extensive hydraulic fracturing and infill drilling to maintain the production rate. Concurrently, the rush towards decarbonization is opening up new possibilities for CO2 utilization, enhanced oil recovery (EOR) being one example. CO2-EOR in unconventional reservoirs presents an opportunity for both financial gain through improved recovery factors, as well as reducing the carbon footprint of the produced oil. In this work, we examine the CO2-EOR potential in 4 organic-rich shale samples from the Canadian Bakken Formation. A number of characterization tests alongside CO2 extraction experiments were performed to gain insight into the controlling factors of CO2-EOR in these ultra-tight formations. The results show CO2 can penetrate the tight rock matrix and recover a substantial amount of hydrocarbon. Concentration gradient driven diffusion is the dominant form of recovery

Asian dustfall in the St. Elias Mountains, Yukon, Canada

In April 2001, a major atmospheric dustfall event occurred in the St. Elias Mountains, Yukon Territory, Canada. Field samples were collected and analyzed for particle size, mineralogy, chemical composition and Sr, Nd and Pb isotopes. Dusts found above 3000 m had their source in the Gobi desert region of northern China and Inner Mongolia, and were transported to the Yukon following a series of major dust storms that took place in early April. Dusts found below 3000 m had local (Yukon) or mixed source(s). The Asian dusts had a modal volume diameter of 4 μm typical of far-traveled mineral aerosols. However larger (>10 μm) particles were also found at 5000 m, suggesting a very rapid trans-Pacific transport in the mid-troposphere. We estimate that the April 2001 event deposited from 5500 to 6335 tons of dust over an area of 21,000 km2 in the southwestern Yukon, most of which probably fell within a week. Our findings are consistent with instrumental observations and model simulations of the April 2001 event. While the dust cloud was reportedly mixed with volatile pollutants from Asia, we found no evidence of metal pollution associated with the dustfall in the Yukon. Our findings contribute to clarify the dynamics and the geochemical impact of Asian dust long-range transport events, and to better estimate eolian fluxes of dustborne elements (e.g., Fe) to the Ocean associated with such events. They may also assist in identifying past Asian dust events in ice cores drilled from the St. Elias Mountains icefields, to develop a long-term record of their frequency, magnitude and source(s)

Clay alteration of volcaniclastic material in a submarine geothermal system, Bay of Plenty, New Zealand

The Calypso Hydrothermal Vent Field (CHVF) is located along an offshore extension of the Taupo Volcanic Zone (TVZ), an area of abundant volcanism and geothermal activity on the North Island of New Zealand. The field occurs within a northeast-trending submarine depression on the continental shelf approximately 10–15 km southwest of the White Island volcano in the Bay of Plenty. The graben has been partially filled by tephra from regional subaerial volcanic eruptions, and active hydrothermal venting occurs at several locations along its length. The vents occur at water depths of 160 to 190 m and have temperatures up to 201 °C. Recovered samples from the vent field include variably cemented and veined volcaniclastic sediments containing an assemblage of clay minerals, amorphous silica, barite, As–Sb–Hg sulfides, and abundant native sulfur. The volcanic glass has been altered primarily to montmorillonite and mixed-layer illite–montmorillonite; illite, and possibly minor talc and mixed-layer chlorite–smectite or chlorite–vermiculite are also present. A hydrothermal versus diagenetic origin for the smectite is indicated by the presence of both illite and mixed-layer clays and by the correlation between the abundance of clay minerals and the abundance of native sulfur in the samples. The mineralization and alteration of the volcanic host rocks are similar to that observed in near-neutral pH geothermal systems on land in the TVZ (e.g., Broadlands–Ohaaki). However, the clay minerals in the CHVF have a higher concentration of Mg in the dioctahedral layer and a higher interlayer Na content than clay minerals from Broadlands–Ohaaki, reflecting the higher concentrations of Mg and Na in seawater compared to meteoric water. Minerals formed at very low pH (e.g., kaolinite and alunite), typical of steam-heated acid-sulfate type alteration in the TVZ geothermal environment, were not found. Mixing with seawater likely prevented the formation of such low-pH mineral assemblages. The occurrence of illite and mixed-layer illite–smectite close to the seafloor in the CHVF, rather than at depth as in the Broadlands system, is interpreted to reflect the higher pressures associated with submarine venting. This allows hotter fluids to be discharged before they boil, and thus minerals that are encountered mainly at depth in subaerial geothermal systems can form close to the seafloor