Strength development with burial in fine-grained sediments from the Saguenay Fjord, Quebec

1995 ◽  
Vol 32 (2) ◽  
pp. 247-262 ◽  
Author(s):  
D. Perret ◽  
J. Locat ◽  
S. Leroueil
Keyword(s):  
Organic Matter ◽  
Strength Development ◽  
Creep Tests ◽  
Fine Grained ◽  
Episodic Events ◽  
Depositional Processes ◽  
Liquidity Index ◽  
Saguenay Fjord ◽  
Continuous Sedimentation ◽  
Marine Clays

Following a sedimentological and geotechnical investigation, two main types of materials were identified in the Saguenay Fjord: (1) organic-rich sediments deposited by continuous sedimentation, and (2) unbioturbated sediments deposited rapidly by episodic events. The consolidation state of sediments with depth were analysed. In all subsurface deposits, sediments are overconsolidated irrespective of the depositional processes. However, in continuously deposited sediments, strength develops more rapidly than in turbidites or mass flows. In the surficial bioturbated layer, strength and liquidity index gradients are at a maximum and the rate of strength variation can reach values as high as 9 kPa/kPa. Results from one-dimensional creep tests suggest that in the organic-poor turbidites, the strength development is controlled, at least partly, by thixotropic strengthening. For bioturbated clays, it appears that the viscosity and the aggregating potential of organic matter controls the evolution of the strength with burial. Key words : Saguenay Fjord, marine clays, consolidation, turbidite, organic matter, bioturbation.

Mercury in the Sediments of the Gulf of St. Lawrence

1975 ◽  
Vol 12 (7) ◽  
pp. 1219-1237 ◽  
Author(s):  
D. H. Loring
Keyword(s):  
Organic Matter ◽  
Total Mercury ◽  
Terrestrial Organic Matter ◽  
Sedimentation Pattern ◽  
Lawrence Estuary ◽  
Fine Grained ◽  
Depositional Processes ◽  
Saguenay Fjord ◽  
Shelf Sediments ◽  
St Lawrence Estuary

In sediments collected from the Saguenay fjord, the St. Lawrence estuary, and open Gulf of St. Lawrence, total mercury varies with sediment texture and location from 10 to 12 300 ppb (average 386 ppb). The highest concentrations occur in the Saguenay fjord (average 2980 ppb) and the lowest in the open Gulf of St. Lawrence (average 150 ppb). The concentration of mercury increases with decreasing grain size, the highest concentrations occur in the fine-grained sediments of the submarine troughs and shelf valleys and the lowest in the sandy shelf sediments. Analyses of the sediments from the Saguenay fjord, where mercury values range from 12 300 ppb at its head to > 500 ppb in the lower reaches, indicate that most of the mercury (70 to 90% of the total) is held by the organic matter in the sediments. The distribution of mercury in the fjord is apparently controlled by the downstream dispersal from local industrial sources of mercury-rich organic matter, most likely of terrestrial origin because of its high C/N ratio. In the St. Lawrence estuary where mercury values range from 30 to 950 ppb, and in the open Gulf where correlations between variables are lower and scattered anomalies exist, analyses indicate that mercury accumulates along with the fine-grained inorganic and organic matter in response to the present depositional processes. The distribution of mercury appears to be controlled by the sedimentation pattern. Terrestrial organic matter and industrial waste originating in the Saguenay drainage area have the strongest influence on its distribution.

Strength development with burial in fine-grained sediments from Saguenay Fjord, Quebec: Reply

1996 ◽  
Vol 33 (1) ◽  
pp. 207-207
Author(s):  
D Perret ◽  
J Locat ◽  
S Leroueil
Keyword(s):  
Strength Development ◽  
Fine Grained ◽  
Saguenay Fjord

scholarly journals The influences of sedimentary environments on organic matter enrichment in fine-grained rocks of the Paleogene Shahejie formation in Nanpu Sag, Huanghua Depression, Bohai Bay Basin

2021 ◽  
pp. 014459872110310
Author(s):  
Min Li ◽  
Xiongqi Pang ◽  
Guoyong Liu ◽  
Di Chen ◽  
Lingjian Meng ◽  
...  
Keyword(s):  
Organic Matter ◽  
Source Rocks ◽  
Bohai Bay ◽  
Bohai Bay Basin ◽  
Humid Climate ◽  
High Productivity ◽  
Fine Grained ◽  
Huanghua Depression ◽  
Shahejie Formation ◽  
Nanpu Sag

The fine-grained rocks in the Paleogene Shahejie Formation in Nanpu Sag, Huanghua Depression, Bohai Bay Basin, are extremely important source rocks. These Paleogene rocks are mainly subdivided into organic-rich black shale and gray mudstone. The average total organic carbon contents of the shale and mudstone are 11.5 wt.% and 8.4 wt.%, respectively. The average hydrocarbon (HC)-generating potentials (which is equal to the sum of free hydrocarbons (S1) and potential hydrocarbons (S2)) of the shale and mudstone are 39.3 mg HC/g rock and 28.5 mg HC/g rock, respectively, with mean vitrinite reflectance values of 0.82% and 0.81%, respectively. The higher abundance of organic matter in the shale than in the mudstone is due mainly to paleoenvironmental differences. The chemical index of alteration values and Na/Al ratios reveal a warm and humid climate during shale deposition and a cold and dry climate during mudstone deposition. The biologically derived Ba and Ba/Al ratios indicate high productivity in both the shale and mudstone, with relatively low productivity in the shale. The shale formed in fresh to brackish water, whereas the mudstone was deposited in fresh water, with the former having a higher salinity. Compared with the shale, the mudstone underwent higher detrital input, exhibiting higher Si/Al and Ti/Al ratios. Shale deposition was more dysoxic than mudstone deposition. The organic matter enrichment of the shale sediments was controlled mainly by reducing conditions followed by moderate-to-high productivity, which was promoted by a warm and humid climate and salinity stratification. The organic matter enrichment of the mudstone was less than that of the shale and was controlled by relatively oxic conditions.

scholarly journals Basin scale distribution of organic matter in marine fine-grained sedimentary rocks: Insight from sequence stratigraphy and multi-proxies analysis in the Montney and Doig Formations

2017 ◽  
Vol 83 ◽  
pp. 382-401 ◽  
Author(s):  
Vincent Crombez ◽  
François Baudin ◽  
Sébastien Rohais ◽  
Laurent Riquier ◽  
Tristan Euzen ◽  
...  
Keyword(s):  
Organic Matter ◽  
Sequence Stratigraphy ◽  
Sedimentary Rocks ◽  
Fine Grained ◽  
Basin Scale

Creep Damage Evaluation of Fine-Grained HAZ in Mod. 9Cr Ferritic Heat-Resistant Steel Weldments

2007 ◽  
Author(s):  
N. Yoneyama ◽  
K. Kubushiro ◽  
H. Yoshizawa
Keyword(s):  
Creep Damage ◽  
Life Time ◽  
Creep Life ◽  
Creep Tests ◽  
Boundary Density ◽  
Fine Grained ◽  
Type Iv ◽  
Fine Grain ◽  
Type Iv Cracking ◽  
Rupture Mechanism

9Cr steel weldments are concerned with evaluation of creep life time and creep rupture mechanism. In fine grain HAZ (FG-HAZ) of weldments, TYPE IV cracking and creep voids occurred at lower stress than rupture stress level of base metal. In the crept specimen, FG-HAZ sometime has large coarsening grains near creep voids. These recovery phenomena are localized in FG-HAZ, and recovered microstructures are dependent on heat input of welding. In this study, creep tests are examined in two types of weldments, and relations between creep life time and coarsened sub-grains or grains have been studied by microstructural changing with EBSP analysis. In crept specimens, boundaries are moved and boundary density is decreasing in the fine-grained HAZ. Maximum grain size and creep life time have linear function, and EBSP can evaluate creep life time of 9Cr weldments. These microstructural changing are considered by morphology of precipitates in the several crept specimens.

Lithofacies, Depositional Environment and Diagenetic Evolution of the Paleocene Patala Formation, Potwar Basin, Pakistan: Implication for Shale Gas Potential

2021 ◽  
Author(s):  
Nasar Khan ◽  
Rudy Swennen ◽  
Gert Jan Weltje ◽  
Irfan Ullah Jan
Keyword(s):  
Organic Matter ◽  
Shale Gas ◽  
Gas Reservoirs ◽  
Shallow Marine ◽  
Anoxic Conditions ◽  
Fine Grained ◽  
Potwar Basin ◽  
Diagenetic Evolution ◽  
Reservoir Assessment ◽  
Gas Potential

<p><span><strong>Abstract:</strong> Reservoir assessment of unconventional reservoirs poses numerous exploration challenges. These challenges relate to their fine-grained and heterogeneous nature, which are ultimately controlled by depositional and diagenetic processes. To illustrate such constraints on shale gas reservoirs, this study focuses on lithofacies analysis, paleo-depositional and diagenetic evolution of the Paleocene Patala Formation at Potwar Basin of Pakistan. Integrated sedimentologic, petrographic, X-ray diffraction and TOC (total organic carbon) analyses showed that the formation contained mostly fine-grained carbonaceous, siliceous, calcareous and argilaceous siliciclastic-lithofacies, whereas carbonate microfacies included mudstone, wackestone and packstone. The silicious and carbonaceous lithofacies are considered a potential shale-gas system. The clastic lithofacies are dominated by detrital and calcareous assemblage including quartz, feldspar, calcite, organic matter and clay minerals with auxiliary pyrites and siderites. Fluctuations in depositional and diagenetic conditions caused  lateral and vertical variability in lithofacies. Superimposed on the depositional heterogeneity are spatially variable diagenetic modifications such as dissolution, compaction, cementation and stylolitization. The δ</span><sup>13</sup><span>C and δ</span><sup>15</sup><span>N stable isotopes elucidated that the formation has been deposited under anoxic conditions, which relatively enhanced the preservation of mixed marine and terrigenous organic matter. Overall, the Patala Formation exemplifies deposition in a shallow marine (shelfal) environment with episodic anoxic conditions.</span></p><p><strong>Keywords</strong><strong>:</strong> Lithofacies, Organic Matter, Paleocene, Potwar Basin, Shale Gas, Shallow Marine.</p>

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