A comparison of joints in bedrock and fractures in overlying Pleistocene lacustrine deposits, central Alberta

1977 ◽  
Vol 14 (3) ◽  
pp. 357-366 ◽  
Author(s):  
E. A. Babcock
Keyword(s):  
Lacustrine Sediments ◽  
Fine Grained ◽  
Lacustrine Deposits

A comparison of bedrock joints with fractures in outcrops of fine-grained Quaternary glaciolacustrine deposits indicates that fractures in the lacustrine sediments are not related to underlying bedrock joints. Fractures in the silts are caused by an exfoliation type of weathering occurring at the outcrop face. They are not reliable indicators of a possible fracture fabric pervading the deposit away from the outcrop scarps.

Electrical resistivity tomography investigations in the ufita Valley (southern Italy).

2008 ◽  
Vol 51 (1) ◽  
Author(s):  
A. Giocoli ◽  
C. Magrì ◽  
P. Vannoli ◽  
S. Piscitelli ◽  
E. Rizzo ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Southern Italy ◽  
Normal Fault ◽  
Fluvial Sediments ◽  
Resistivity Tomography ◽  
Fine Grained ◽  
Sedimentary Deposits ◽  
Lacustrine Deposits ◽  
Sedimentary Deposit

Several Electrical Resistivity Tomography (ERT) surveys have been carried out to study the subsurface structural and sedimentary settings of the upper Ufita River valley, and to evaluate their efficiency to distinguish the geological boundary between shallow Quaternary sedimentary deposits and clayey bedrock characterized by moderate resistivity contrast. Five shallow ERTs were carried out across a morphological scarp running at the foot of the northeastern slope of the valley. This valley shoulder is characterized by a set of triangular facets, that some authors associated to the presence of a SW-dipping normal fault. The geological studies allow us to interpret the shallow ERTs results obtaining a resistivity range for each Quaternary sedimentary deposit. The tomographies showed the geometrical relationships of alluvial and slope deposits, having a maximum thickness of 30-40 m, and the morphology of the bedrock. The resistivity range obtained for each sedimentary body has been used for calibrating the tomographic results of one 3560m-long deep ERT carried out across the deeper part of the intramountain depression with an investigation depth of about 170 m. The deep resistivity result highlighted the complex alluvial setting, characterized by alternating fine grained lacustrine deposits and coarser gravelly fluvial sediments.

UNUSUAL FOSSILIFEROUS CONCRETIONS FROM LACUSTRINE DEPOSITS IN THE LOWER JURASSIC MOENAVE FORMATION IN ST. GEORGE, UTAH, USA: IMPLICATIONS FOR ANCIENT FISH MASS MORTALITIES

Palaios ◽  
2020 ◽  
Vol 35 (2) ◽  
pp. 77-93
Author(s):  
ALLISON R. VITKUS ◽  
KAREN CHIN ◽  
JAMES I. KIRKLAND ◽  
ANDREW R.C. MILNER ◽  
EDWARD L. SIMPSON ◽  
...  
Keyword(s):  
Microbial Mats ◽  
Lacustrine Sediments ◽  
Lower Jurassic ◽  
Lacustrine Deposits ◽  
Diagenetic Alteration ◽  
Different Shapes ◽  
Metabolic Activities ◽  
The Masses ◽  
Mass Mortalities ◽  
Moenave Formation

ABSTRACT Two types of unusual concretions with similar biotic contents but markedly different shapes and distributions were found in close stratigraphic proximity within the Lower Jurassic Whitmore Point Member of the Moenave Formation in St. George, Utah. Both types of concretions formed in lacustrine sediments and contain abundant ganoid fish scales, numerous ostracode carapaces, and apparent rip-up clasts. Elongate, cylindrical concretions developed in parallel and regularly spaced rows in one horizon, and comparatively flat and irregularly shaped and distributed concretions formed in an overlying layer only a few centimeters above. Microprobe and Raman analyses of concretion samples reveal abundant hematite in both concretions as well as groundmass minerals dominated by silica in the cylindrical concretions and dolomite in the flat concretions. The abundance of fish skeletal debris in concretions from two consecutive horizons may suggest recurring fish mass mortality in ancient Lake Dixie, the large lake that occupied the St. George area during the Early Jurassic. We propose a model for the formation of the concretions based on their shapes, distributions, and chemistry. In this model, accumulations of disarticulated fish debris were colonized and consolidated by microbial mats and shaped by oscillatory flow (in the case of the cylindrical concretions) or lack thereof (in the case of the flat concretions). Then, after burial, groundwater chemistry and possibly the metabolic activities of microorganisms led to the precipitation of minerals around and within the masses of fish material. Finally, diagenetic alteration changed the mineral makeups of the cylindrical and flat concretions into what they are today.

scholarly journals A key continental archive for the last 2 Ma of climatic history of the central Mediterranean region: A pilot drilling in the Fucino Basin, central Italy

2015 ◽  
Vol 20 ◽  
pp. 13-19 ◽  
Author(s):  
B. Giaccio ◽  
E. Regattieri ◽  
G. Zanchetta ◽  
B. Wagner ◽  
P. Galli ◽  
...  
Keyword(s):  
Central Italy ◽  
Lacustrine Sediments ◽  
Mediterranean Area ◽  
Central Mediterranean ◽  
Fine Grained ◽  
Xrf Scanning ◽  
History Of ◽  
Sedimentary Succession ◽  
Geochemical Analyses ◽  
Fucino Basin

Abstract. An 82 m long sedimentary succession was retrieved from the Fucino Basin, the largest intermountain tectonic depression of the central Apennines. The basin hosts a succession of fine-grained lacustrine sediments (ca. 900 m-thick) possibly continuously spanning the last 2 Ma. A preliminary tephrostratigraphy study allows us to ascribe the drilled 82 m long record to the last 180 ka. Multi-proxy geochemical analyses (XRF scanning, total organic/inorganic carbon, nitrogen and sulfur, oxygen isotopes) reveal noticeable variations, which are interpreted as paleohydrological and paleoenvironmental expressions related to classical glacial–interglacial cycles from the marine isotope stage (MIS) 6 to present day. In light of the preliminary results, the Fucino sedimentary succession is likely to provide a long, continuous, sensitive, and independently dated paleoclimatic archive of the central Mediterranean area.

scholarly journals Sedimentology and stratigraphy of the type section of the Pennsylvanian Boss Point Formation, Joggins Fossil Cliffs, Nova Scotia, Canada

2015 ◽  
Vol 51 (1) ◽  
pp. 001 ◽  
Author(s):  
Michael C. Rygel ◽  
Corinne Lally ◽  
Martin R. Gibling ◽  
Alessandro Ielpi ◽  
John H. Calder ◽  
...  
Keyword(s):  
Nova Scotia ◽  
Lacustrine Sediments ◽  
World Heritage Site ◽  
Fine Grained ◽  
Type Section ◽  
The North ◽  
Heritage Site ◽  
Unesco World Heritage Site ◽  
Floodplain Deposits ◽  
Fluvial Sandstone

<p style="margin: 0in 0in 0pt;"><span style="font-family: 'Minion Pro','serif';"><span style="font-size: medium;">The 1125-m-thick type section of the Pennsylvanian Boss Point Formation is well exposed along the shore of the Bay of Fundy in Nova Scotia. We provide the first comprehensive account of the entirety of this formation, which comprises nearly one-third of the stratigraphic thickness of the Joggins Fossil Cliffs UNESCO World Heritage Site. The basal Chignecto Bay Member (0–91.5 m) is composed of redbeds, single-storey channel bodies with northerly paleoflow, and thin palustrine limestones. The middle Ward Point Member (91.5–951.7 m) contains up to 16 megacycles composed of alternations between thick packages of braided fluvial sandstone and fine-grained deposits. Although regional studies of the Boss Point Formation suggest that the fine-grained deposits are largely composed of lacustrine sediments, these intervals consist largely of poorly drained and well-drained floodplain deposits in the type section. The facies variations and southeast-directed paleoflow in the Ward Point Member record modest uplift associated with the growth of the salt-cored Minudie Anticline. The North Reef Member (951.7–1125 m) is composed of redbeds and two distinctive multistorey channel bodies. This uppermost member records a shift to more arid, oxidizing conditions, was the precursor to a major phase of salt withdrawal, and represents a transition to the overlying Little River Formation. The sedimentological framework, revised stratigraphy, and detailed measured section and map will provide a foundation for future study of this remarkable Pennsylvanian exposure.</span></span></p>

Lightweight Corer Designed for Sampling Very Soft Sediments

1979 ◽  
Vol 36 (3) ◽  
pp. 241-246 ◽  
Author(s):  
J. D. H. Williams ◽  
A. E. Pashley
Keyword(s):  
Key Words ◽  
Optical Sensor ◽  
Lacustrine Sediments ◽  
Water Interface ◽  
Soft Sediments ◽  
Fine Grained

An underwater corer has been developed capable of taking 10-cm diam cores up to 1 m long from unconsolidated, fine-grained fluvial and lacustrine sediments including organic-rich (gyttja-like) deposits. The corer is lightweight and compact for transport and hand operation from float planes and small boats. It is of the piston type and has a sphincter valve for core retention. A miniature optical sensor triggers the corer when the sediment–water interface is penetrated. The corer is compatible with a system to subdivide the cores by vertical extrusion. Key words: corer, sediment, piston, sampling

Biogeochemical Characteristics of Lacustrine Sediments Reflecting a Changing Alpine Neotropical Ecosystem during the Pleistocene

2002 ◽  
Vol 58 (2) ◽  
pp. 189-196 ◽  
Author(s):  
Germán Mora ◽  
Lisa M. Pratt ◽  
Arnoud Boom ◽  
Henry Hooghiemstra
Keyword(s):  
Algal Blooms ◽  
Lacustrine Sediments ◽  
Organosulfur Compounds ◽  
Alpine Ecosystems ◽  
Tropical Andes ◽  
Isotopic Signatures ◽  
Climatic Variations ◽  
Lacustrine Deposits ◽  
Reducing Conditions ◽  
Vegetation Expansion

AbstractContinuous lacustrine deposits of the Funza-II core from the Bogotá basin, Colombia (5°N74°W) record late Pleistocene climatic variations, providing an opportunity to assess the influence of glacial–interglacial climate changes on alpine ecosystems in equatorial South America. Biogeochemical response of this tropical alpine system to climate change was inferred from changes in elemental concentrations and ratios and isotopic signatures in the upper 120 m of the lacustrine Funza core.Values of δ13Corg exhibit eight abrupt, positive shifts that are thought to reflect rapid expansions of C4 grasses in the tropical Andes and algal blooms. One of these excursions, interpreted to correspond to C4 vegetation expansion, occurred in sediments accumulated during the last glaciation (∼30,000–50,000 yr B.P.) and implies a downslope shift of the upper Andean treeline, regardless of prevailing temperatures.Sedimentary carbon/sulfur ratios are low and indicate significant sequestering of sulfur. Monosulfides are the dominant constituent of sedimentary sulfur during relatively humid intervals, when increased supply of iron caused by enhanced weathering favored the formation of monosulfide minerals under strongly reducing conditions. In contrast, organosulfur compounds dominate the sedimentary sulfur-species in relatively drier intervals when mildly reducing conditions and limited iron input promoted the diagenetic incorporation of sulfur in organic matter. Dry events inferred from the sulfur record typically correlate with glacial maxima, whereas glacial terminations are usually associated with wet periods.

New insights on Illinoian deglaciation from deposits of Glacial Lake Quincy, central Indiana

2010 ◽  
Vol 73 (2) ◽  
pp. 374-384 ◽  
Author(s):  
J.R. Wood ◽  
S.L. Forman ◽  
J. Pierson ◽  
J. Gomez
Keyword(s):  
Oxygen Isotope ◽  
Sea Level ◽  
Lacustrine Sediments ◽  
Glacial Lake ◽  
Depositional Facies ◽  
Oxygen Isotope Stage ◽  
Fine Grained ◽  
Blue Excitation ◽  
Global Sea Level ◽  
Maximum Limit

The deposits of Glacial Lake Quincy overlie a diamicton associated with the classically defined Illinoian limit in central Indiana. This lake covered at least 180 km2 with a depth of > 20 m and developed when the Illinoian ice sheet retreated 15 km from the maximum limit, causing lake impoundment against Devore Ridge. Overflow from Glacial Lake Quincy eroded across the ridge forming a number of steeped-walled outlets. A section along Mill Creek exposes a sedimentologic sequence associated with Glacial Lake Quincy from a subglacial diamicton to ice-proximal to ice-distal glacial lacustrine sediments. We report new optical ages by multiple aliquot regenerative dose procedure for the fine-grained rhythmically bedded sediments presumed to represent the lowest energy depositional facies, dominated by suspension settling, which maximized sunlight exposure. In turn, optical ages were determined on the fine-grained (4-11 μm) polymineral and quartz fractions under infrared and blue excitation, which yielded statistically similar ages. Optical ages span from ca. 170 to 108 ka, with the average of 16 optical ages indicating deglaciation at ca. 135 ka, generally coincident with Marine Oxygen Isotope Stage 6-to-5 transition and rise in global sea level.

scholarly journals Late Miocene sedimentary record of the Danube/Kisalföld Basin: interregional correlation of depositional systems, stratigraphy and structural evolution

2016 ◽  
Vol 67 (6) ◽  
pp. 525-542 ◽  
Author(s):  
Orsolya Sztanó ◽  
Michal Kováč ◽  
Imre Magyar ◽  
Michal Šujan ◽  
László Fodor ◽  
...  
Keyword(s):  
Late Miocene ◽  
Pannonian Basin ◽  
Lacustrine Sediments ◽  
Structural Evolution ◽  
Fluvial Systems ◽  
Lake Pannon ◽  
Fine Grained ◽  
The North ◽  
Shelf Slope

AbstractThe Danube / Kisalföld Basin is the north-western sub-basin of the Pannonian Basin System. The lithostratigraphic subdivision of the several-km-thick Upper Miocene to Pliocene sedimentary succession related to Lake Pannon has been developed independently in Slovakia and Hungary. A study of the sedimentary formations across the entire basin led us to claim that these formations are identical or similar between the two basin parts to such an extent that their correlation is indeed a matter of nomenclature only. Nemčiňany corresponds to the Kálla Formation, representing locally derived coarse clastics along the basin margins (11- 9.5 Ma). The deep lacustrine sediments are collectively designated the Ivanka Formation in Slovakia, while in Hungary they are subdivided into Szák (fine-grained transgressive deposits above basement highs, 10.5 - 8.9 Ma), Endrőd (deep lacustrine marls, 11.6 -10 Ma), Szolnok (turbidites, 10.5 - 9.2 Ma) and Algyő Formations (fine-grained slope deposits, 10 - 9 Ma). The Beladice Formation represents shallow lacustrine deltaic deposits, fully corresponding to Újfalu (10.5 - 8.7 Ma). The overlying fluvial deposits are the Volkovce and Zagyva Formations (10 - 6 Ma). The synoptic description and characterization of these sediments offer a basin-wide insight into the development of the basin during the Late Miocene. The turbidite systems, the slope, the overlying deltaic and fluvial systems are all genetically related and are coeval at any time slice after the regression of Lake Pannon initiated about 10 Ma ago. All these formations get younger towards the S, SE as the progradation of the shelf-slope went on. The basin got filled up to lake level by 8.7 Ma, since then fluvial deposition dominated.

Late Quaternary Environmental Changes in the Upper Las Vegas Valley, Nevada

1986 ◽  
Vol 26 (3) ◽  
pp. 340-357 ◽  
Author(s):  
Jay Quade
Keyword(s):  
Great Basin ◽  
Environmental Changes ◽  
Las Vegas ◽  
Late Quaternary ◽  
Vegetation Changes ◽  
Fine Grained ◽  
Lacustrine Deposits ◽  
Las Vegas Valley ◽  
Carbonate Cementation ◽  
Late Pleistocene To Holocene

Five stratigraphic units and five soils of late Pleistocene to Holocene age crop out in dissected badlands on Corn Creek Flat, 30 km northwest of Las Vegas, Nevada, and at Tule Springs, nearer to Las Vegas. The record is dominantly fluvial but contains evidence of several moister, marsh-forming periods: the oldest (Unit B) dates perhaps to the middle Wisconsin, and the more widespread Unit D falls between 30,000 and 15,000 yr B.P. Unit D therefore correlates with pluvial maximum lacustrine deposits elsewhere in the Great Basin. Standing water was not of sufficient depth or extent during either period to form lake strandlines. Between 14,000 and 7200 yr B.P. (Unit E), standing surface water gradually decreased, a trend also apparent in Great Basin pluvial lake chronologies during the same period. Groundwater carbonate cementation and burrowing by cicadas (Cicadae) accompany the moist-phase units. After 7200 yr B.P., increased wind action, decreased biotic activity, and at least 25 m of water-table lowering accompanied widespread erosion of older fine-grained deposits. Based on pack-rat midden and pollen evidence, this coincides with major vegetation changes in the valley, from sagebrush-dominated steppe to lower Mohave desertscrub.

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