scholarly journals Buried Ancient Forest and Implications for Paleoclimate Since the Mid-Holocene in South China

Radiocarbon ◽  
2010 ◽  
Vol 52 (3) ◽  
pp. 1411-1421 ◽  
Author(s):  
C D Shen ◽  
P Ding ◽  
N Wang ◽  
W X Yi ◽  
X F Ding ◽  
...  
Keyword(s):  
South China ◽  
High Latitude ◽  
Silty Clay ◽  
Historical Evolution ◽  
Ice Ages ◽  
Climate Fluctuations ◽  
Ancient Forest ◽  
Clay Layers

The historical evolution of an ancient forest that developed at Gaoyao, south China, can be divided into 4 stages of radiocarbon intervals (1.1–1.5, 2.0–3.5, 3.6–4.0, and 4.3–4.9 ka) in which the last 3 stages all developed in a wetland and formed humic layers of 2.0, 0.5, and 0.7 m depth, respectively. The humic layers were interrupted by 2 white-gray silty clay layers that most likely formed during climate fluctuations. Four drought events were identified during the evolution of the ancient forest, occurring around 4.3, 3.6, 2.0, and 1.1 ka, respectively, with durations of ∼1000 14C yr. These events are consistent with other records both in low- and high-latitude areas, in particular with the little ice ages occurring since the mid-Holocene. Precipitation likely increased from 5.0 to 3.6 ka in south China, then decreased, which is probably the main cause for the development as well as the demise of the ancient forest.

scholarly journals The oceanographic contribution of James Croll

2021 ◽  
pp. 1-7
Author(s):  
Alastair DAWSON
Keyword(s):  
Ocean Circulation ◽  
High Latitude ◽  
First Principles ◽  
Heat Supply ◽  
Real Data ◽  
Ocean Currents ◽  
Ice Ages ◽  
Scientific Exploration ◽  
The Many

ABSTRACT The research of James Croll on the nature of Ice Ages led him into a detailed investigation of ocean currents. By the early 1870s he had calculated from first principles the quantities of heat delivered by ocean currents to high latitude areas and he understood how this heat supply may have altered drastically during ice ages. The publication of his many papers on ocean currents as well as his book, Climate and Time, coincided with Challenger expedition that, in 1872, embarked on a 4-year voyage of scientific exploration of the world's oceans. The expedition was crucially important for Croll since it enabled him to test his theories of ocean circulation using real data. His novel theories of ocean circulation based on this information conflicted with the established views popularly advocated by William Carpenter but they ultimately prevailed. In the many writings of Croll on ocean currents, we encounter, as with other areas of his research, numerous remarkable ideas many decades ahead their time.

scholarly journals Elevated gas hydrate saturation within silt and silty clay sediments in the Shenhu area, South China Sea

2011 ◽  
Vol 116 (B5) ◽  
Author(s):  
Xiujuan Wang ◽  
Deborah R. Hutchinson ◽  
Shiguo Wu ◽  
Shengxiong Yang ◽  
Yiqun Guo
Keyword(s):  
South China Sea ◽  
South China ◽  
Gas Hydrate ◽  
Silty Clay ◽  
Shenhu Area ◽  
China Sea ◽  
Hydrate Saturation

scholarly journals Forming conditions of the Graikas lignite, N. Peloponnese

2001 ◽  
Vol 34 (3) ◽  
pp. 1195 ◽  
Author(s):  
Σ. ΚΑΛΑΪΤΖΙΔΗΣ ◽  
Σ. ΠΑΠΑΖΗΣΙΜΟΥ ◽  
Κ. ΧΡΗΣΤΑΝΗΣ
Keyword(s):  
Influence Factor ◽  
Volatile Matter ◽  
Low Rank ◽  
Early Pleistocene ◽  
Silty Clay ◽  
Inorganic Matter ◽  
Pyrite Content ◽  
Marine Influence ◽  
Clay Layers ◽  
Coal Petrography

In Northern Péloponnèse (southern Greece) several lignite seams occur, many of which were exploited in the past decades. In the small Graikas basin, in the upland Aigialia, a 2.5-m-thick lignite seam outcrops within the Pliocene/ Pleistocene sediments. The pre-Neogene margins and the basement of the basin consist of radiolarites, pelagic limestones, and flysch of the Pindos isopic zone. The sediments filling the basin include marly, sandy and clay layers, which deposited under marine, brackish and lacustrine conditions, during the rifting of the Corinth graben (Late Pliocene-Early Pleistocene). The seam consists of lignite and clay-rich lignite layers, of matrix lithotype, with total thickness of 1.4 m, intercalating with thin marly, silty, clay and humic clay layers. Fourteen lignite samples were obtained for proximate and ultimate analyses and coal-petrography studies. The ash contents of the Graikas lignite range up to 46.2% on dry base revealing intense inorganic input. The total sulphur contents are also high up to 4%. The fixed carbon and volatile matter contents (33.2-46% and 53.9-66.8% on daf, respectively), as well as the H/C and O/C atomic ratios and the reflectance of Eu-ulminite Β (Rm 0.26-0.30%), indicate a low rank (soft brown coal, Weichbraunkohle). Micropetrographic studies revealed a Huminite content >73%, Liptinite <23%, and Inertinite <12%. Attrinite and Densinite are the most prevailing macérais, while Texto-ulminite A and Eu-ulminite A show moderate values. Inertodetrinite and Semi-fusinite dominate within the Inertinite macerai group. Cutinite and Liptodetrinite are the most abundant macérais of the Liptinite group. Mainly clay and carbonate minerals constitute the inorganic matter (7-30%). However, pyrite content is also significantly high, up to 10%, revealing anoxic marine influence. Factor analysis suggests that peat accumulation started under anoxic conditions and intense bacterial activity. The peat-forming vegetation was mostly herbaceous with minor contribution of arboreal vegetation. Moreover, negative correlation is revealed between the gelification degree and the inorganic input. Coal-facies diagrammes suggest low preservation of the organic tissues and highly scattered gelificationindeces. The peat in the Graikas basin started accumulating in a lagoonal environment under brackish conditions behind a barrier. Progressively, sea regraded and the conditions became limnic to limnotelmatic

Leaf Wax and Sr‐Nd Isotope Evidence for High‐Latitude Dust Input to the Central South China Sea and Its Implication for Fertilization

2021 ◽  
Vol 48 (11) ◽  
Author(s):  
Yi Yang ◽  
James A. Bendle ◽  
Richard D. Pancost ◽  
Yan Yan ◽  
Xiaoyan Ruan ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
High Latitude ◽  
Nd Isotope ◽  
China Sea ◽  
Leaf Wax ◽  
Isotope Evidence ◽  
Central South

Rapid decline of a relatively high latitude coral assemblage at Weizhou Island, northern South China Sea

2019 ◽  
Vol 28 (14) ◽  
pp. 3925-3949 ◽  
Author(s):  
Wanjun Yu ◽  
Wenhuan Wang ◽  
Kefu Yu ◽  
Yinghui Wang ◽  
Xueyong Huang ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
High Latitude ◽  
Northern South China Sea ◽  
Rapid Decline ◽  
China Sea ◽  
Coral Assemblage

scholarly journals DISTRIBUTION OF GASES IN BOTTOM SEDIMENTS OF THE SOUTHWESTERN SUB-BASIN OF THE SOUTH CHINA SEA (BIEN DONG)

2021 ◽  
pp. 67-77
Author(s):  
Le Duc Luong ◽  
◽  
A.I. Obzhirov ◽  
Nguyen Hoang ◽  
R.B. Shakirov ◽  
...  
Keyword(s):  
South China Sea ◽  
Bottom Sediments ◽  
South China ◽  
The South China Sea ◽  
Background Concentration ◽  
Silty Clay ◽  
The South ◽  
Hydrocarbon Gases ◽  
China Sea ◽  
Wide Range

For the first time, this paper presents the distribution of gases (CO2, hydrocarbon C1-C4, H2, He) in 39 gas samples in bottom sediments from 19 gravity cores located in the southwestern sub-basin of the South China Sea (known as Bien Dong). The surface sediments in the studied area are mostly silty clay. In general, the concentration of methane varies in a wide range of 0.5–440 ppm. Anomalous values of methane were detected at many locations along the slope area of the southwest sub-basin of the South China Sea. The value of 2.2 ppm could be considered as a background concentration of methane in the studied region. The presence of a large-scale degassing zone of methane in the studied area was proposed. Besides, heavy hydrocarbon gases (ethylene, ethane, propane, and butane) were also determined with the highest values up to 70 ppm, 124 ppm, and 50 ppm for ethylene, ethane and propane, respectively. In addition, data of carbon dioxide, hydro and helium suggest some anomalous values of H2 up to 56.7 ppm.

scholarly journals Gas Hydrate System of Shenhu Area, Northern South China Sea: Geochemical Results

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Nengyou Wu ◽  
Haiqi Zhang ◽  
Shengxiong Yang ◽  
Guangxue Zhang ◽  
Jinqiang Liang ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Gas Hydrate ◽  
Northern South China Sea ◽  
River Mouth ◽  
Geochemical Data ◽  
Pearl River Mouth Basin ◽  
Silty Clay ◽  
Shenhu Area ◽  
China Sea

The drilling recovered high-concentration methane hydrates (maximum 26–48%) in a disseminated form in silty clay sediments in Shenhu area of Pearl River Mouth Basin, South China Sea. Combining the geochemical data, the gas hydrate-bearing sediments are 10 m to 43 m in thickness and located just above the base of the gas hydrate stability zone. The methane content is 96.10–99.91% with small amount of ethane and propane. The baseline chlorinity of pore waters shows 10% lower than that of shallow sediments below and inside the gas hydrate zone. The methane/ethane ratios are higher than 1000 above the gas hydrate zone and less than 1000 at the interval of gas hydrate zone. The depth of sulphate methane interface varies from site to site as 17 to 27 mbsf. These results show that the methane of gas hydrate was mainly originated from microbial activity and the upward methane flux is minor. This is evidenced by the δC13CH4 values of headspace gases from the gravity piston cores and released gases from pressure cores, which range from −74.3‰  PDB to −46.2‰  PDB, with the majority less than −55%‰  PDB. The hydrate deposit is a distributed gas hydrate system in Shenhu area.

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