Geosteering Using True Stratigraphic Thickness

2013 ◽  
Author(s):  
Charles R. Berg ◽  
Andrew C. Newson
Keyword(s):  
Stratigraphic Thickness

A Huronian outlier in the Goulais River area, District of Algoma, Ontario

1978 ◽  
Vol 15 (9) ◽  
pp. 1535-1537 ◽  
Author(s):  
E. C. Grunsky ◽  
J. T. Arengi
Keyword(s):  
Sedimentary Rock ◽  
Sedimentary Rocks ◽  
Photo Interpretation ◽  
Field Mapping ◽  
Nearby Source ◽  
Air Photo ◽  
Stratigraphic Thickness

An outlier of sedimentary rock assigned to the Gowganda Formation of the Huronian Supergroup was discovered during field mapping in the Goulais River area, District of Algoma, Ontario. This outlier is the northernmost documented occurrence of Huronian sedimentary rocks in the Algoma region. The outlier is 53 m in stratigraphic thickness and consists of polymictic to oligomictic paraconglomerate and orthoconglomerate with interbeds of pink arkose, siltstone, and dark grey greywacke. The conglomerates contain metavolcanic fragments and altered feldspars that suggest part of the sediment had a nearby source. Hematite results in a pink matrix in both conglomerates and arkosic interbeds and may indicate that an oxidizing environment prevailed during deposition. Air photo interpretation may help locate other outliers in the vicinity of lineaments, faults, or topographic highs.

Determination of stratigraphic thickness of strained units

1978 ◽  
Vol 15 (8) ◽  
pp. 1379-1380 ◽  
Author(s):  
W. M. Schwerdtner
Keyword(s):  
The State ◽  
Principal Plane ◽  
Theoretical Development ◽  
Total Strain ◽  
Bedding Surface ◽  
Stratigraphic Thickness

Given the state of homogeneous total strain or average total strain of a deformed unit, its stratigraphic thickness can be readily determined. The necessary theoretical development is presented herein, together with a general discussion of the necessary equations. It is shown that the practice of destraining lines of true thickness of deformed strata is theoretically sound only if the bedding surface is a principal plane of deformation.

scholarly journals Arquitectura estratigráfica, paleogeografía y proveniencia sedimentaria de las rocas cenozoicas del sur de Perú (Tacna, 18° S)

2020 ◽  
Vol 47 (2) ◽  
pp. 351
Author(s):  
Aldo A. Alvan ◽  
Yacory F. Bustamante ◽  
Elvis A. Sánchez ◽  
Mirian I. Mamani
Keyword(s):  
Sedimentary Facies ◽  
Normal Faults ◽  
Architectural Elements ◽  
Western Cordillera ◽  
Stratigraphic Framework ◽  
Basal Complex ◽  
Facies Associations ◽  
Sediment Mineralogy ◽  
Sedimentary Fill ◽  
Stratigraphic Thickness

The Cenozoic rocks lying in the Province of Tacna (18° S), southern Perú, represent approximately 600 m of stratigraphic thickness. This stacking groups the Sotillo (Paleocene), Moquegua Inferior (Eocene), Moquegua Superior (Oligocene), Huaylillas (Miocene) and Millo formations (Pliocene), and these are the sedimentary fill of the Moquegua Basin. The sediments of the three latter formations are organized into nine sedimentary facies and five architectural elements. Their facies associations suggest the existence of an ancient highly channelized multi-lateral fluvial braided system, with upward increase of pyroclastic and conglomeratic depositions. The heavy mineral spectra make each lithostratigraphic unit unique and distinguishable, being the sediments of the Moquegua Superior Formation rich in garnets, titanites and zircons; while the sediments of the Huaylillas and Millo formations in clinopyroxenes. This mineral arrangement becomes an excellent tool for stratigraphic correlations between outcrops and subsurface stratigraphy (by means of well cores studies) and allow to sketch out a new stratigraphic framework and a complex of rocky blocks bounded by normal faults, often tilted. The sediment mineralogy also suggests that the rocks conforming the Western Cordillera were the main source of sediments for the Moquegua Basin in Tacna. In this context, the detritus of the Moquegua Superior Formation derives mainly from the erosion of the rocks forming the Coastal Basal Complex (Proterozoic), the Ambo Group (Carboniferous) and the Junerata/Chocolate Formation (Early Jurassic). The Huaylillas Formation is a pyroclastic and sedimentary unit which components derived mainly from the Huaylillas volcanism (Miocene) and partly from the denudation of the Toquepala Group (Late Cretaceous). The Huaylillas Formation widely contrasts to the underlying Moquegua Superior Formation due its mineralogy and facies. Finally, the detritus of the Millo Formation derived mostly from the rocks forming the Barroso Formation (Pliocene), and their facies represent a higher contrast in relation to the underlying units due its notorious conglomerate facies.

Solidification timescale for the Dufek Intrusion, Antarctica determined by U-Pb zircon ages

2020 ◽  
Author(s):  
Jill VanTongeren ◽  
Aidan Taylor ◽  
Blair Schoene
Keyword(s):  
Bushveld Complex ◽  
Lower Section ◽  
Magma Chambers ◽  
Skaergaard Intrusion ◽  
Mafic Intrusion ◽  
Three Samples ◽  
Two Samples ◽  
Mineral Compositions ◽  
Layered Mafic Intrusion ◽  
Stratigraphic Thickness

<p>The 8-9 km thick Dufek layered mafic intrusion of Antarctica was emplaced at approximately 182 Ma associated with the Ferrar dolerites and the breakup of the supercontinent Gondwana.  It is rivaled in thickness only by the Bushveld Complex of South Africa and shows a similar progression in mineral compositions all the way to the uppermost contact with an overlying granophyre layer.  This progression in mineral composition suggests that it crystallized from the bottom to the top and did not form an upper solidification front (a.k.a., Upper Border Series) typical of smaller intrusions such as the Skaergaard Intrusion.  Unlike the Bushveld Complex, however, the Dufek Intrusion is exposed in only two ~1.8 km thick sections: the lowermost Dufek Massif, and the uppermost Forrestal Range, which are separated from one another by a ~50km wide snowfield.  The remainder of the stratigraphy is inferred from geophysics, evolution of mineral compositions, and projection of the dip of the layering through the snowfield. </p><p> </p><p>            We obtained precise CA-ID-TIMS U-Pb zircon ages from samples from the Dufek Massif and Forrestal Range in order to determine the timescale of solidification of a large layered mafic intrusion.  What we found is surprising - zircons from the bottom of the intrusion record younger ages than those from the top of the intrusion.  Two samples from the Dufek Massif have zircon U-Pb ages of 182.441±0.048 Ma and 182.496±0.057 Ma; whereas three samples from the Forrestal Range have zircon U-Pb ages of 182.601±0.064 Ma, 182.660±0.10 Ma, 182.78±0.21 Ma.  Thus, the lower section of the Dufek Intrusion solidified approximately 160,000 years after the upper.  We explore two possibilities for this reverse-age stratigraphy, (1) that the ages reflect the solidification of interstitial melt in a single magma chamber cooling from the top down, or (2) that the Dufek Massif and Forrestal Range are two separate magma chambers that are not connected at depth.  Our results have implications for the stratigraphic thickness estimates of the Dufek Intrusion as well as the duration of magmatism associated with continental breakup.</p><p> </p><p> </p>

scholarly journals Sedimentary basin analysis of the continental Devonian basin in North-East Greenland

1993 ◽  
Vol 168 ◽  
pp. 1-80
Author(s):  
H Olsen
Keyword(s):  
Sedimentary Basin ◽  
Basin Analysis ◽  
East Greenland ◽  
North East ◽  
Drainage Patterns ◽  
Stratigraphic Thickness

Continental Devonian sediments attain a stratigraphic thickness in excess of 8000 m in North-East Greenland. Four tectonostratigraphic basin stages are recognized in the succession defined by drainage patterns and bounding unconformities and named according to their constituent Iithostratigraphic units. The oldest Vilddal basin stage exhibits eastward drainage, the succeeding Kap Kolthoff - Kap Graah basin stage exhibits southward drainage, northward drainage characterizes the Celsius Bjerg basin stage, and southwestward drainage is characteristic of the youngest Harder Bjerg basin stage.

scholarly journals Volcanic history of the Lower Tertiary plateau basalts in the Scoresby Sund region, East Greenland

1986 ◽  
Vol 128 ◽  
pp. 147-156
Author(s):  
W.S Watt ◽  
L.M Larsen ◽  
M Watt
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Atlantic Coast ◽  
Basalt Lava ◽  
The North ◽  
Lava Sequence ◽  
History Of ◽  
The North Atlantic ◽  
Lava Pile ◽  
Stratigraphic Thickness

The extensive plateau basalt lava pile in the Scoresby Sund region has a stratigraphic thickness of 3200 m and an overall average thickness of 1500 m. The pile thins inland from the Atlantic coast and laps onto basement gneisses and Jurassic sediments in the inner fjord region. The lavas are divisible into five formations which form two separate lava sequences. The lower sequence is best developed in the inner fjord region, while the upper sequence dominates the regions near the Atlantic coast. The sequences are interpreted as produced in two vo\canic episodes in connection with failed rifting episodes during the opening of the North Atlantic Ocean. At the Atlantic coast remains of a third separate lava sequence apparently forrned during active spreading.

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