scholarly journals Descriptions of drill cores and thin sections from lower Paleozoic strata, southeastern Baffin Island shelf, Nunavut

2018 ◽  
Author(s):  
N Bingham-Koslowski
Keyword(s):  
Baffin Island ◽  
Lower Paleozoic ◽  
Thin Sections ◽  
Island Shelf ◽  
Drill Cores

Biodiversity of the Silurian osteostracans of the East Baltic

2014 ◽  
Vol 105 (2) ◽  
pp. 73-148 ◽  
Author(s):  
T. Märss ◽  
O. Afanassieva ◽  
H. Blom
Keyword(s):  
New Taxa ◽  
Thin Sections ◽  
Histological Characteristics ◽  
First Time ◽  
Drill Cores

ABSTRACTThe sculpture and histology of osteostracan head shields and trunk squamations from the Silurian of Estonia are described, illustrated and used for the identification of disarticulated microremains collected from outcrop sections and numerous drill cores in Estonia and Latvia over the last 40 years. The scattered osteostracan material contains thousands of specimens of scales and shield fragments. The sculpture and histology of species of the previously identified eight genera in the region (Tremataspis, Dartmuthia, Saaremaaspis, Oeselaspis, Aestiaspis, Thyestes, Procephalaspis, Witaaspis) are redescribed, together with Ateleaspis, found in Estonia for the first time. The sculpture on the cornua of several taxa is described for the first time. The new taxa Tremataspis perforata sp. nov., Dartmuthia procera sp. nov., Eldaaspis miklii gen. et sp. nov., Tahulaspis ordinata gen. et sp. nov., Tahulaspis praevia gen. et sp. nov., Meelaidaspis gennadii gen. et sp. nov. and Ohesaareaspis ponticulata gen. et sp. nov. are established, based upon sculpture and histological characteristics of the exoskeleton. The supraoral field with denticles of that field are described for the first time in Oeselaspis pustulata, as is the supraoral plate with buccal denticles in Meelaidaspis gennadii gen. et sp. nov. Thin sections of all taxa (except of Witaaspis) have been studied. This work sheds light on East Baltic osteostracan biodiversity from the Maasi Beds of the Jaagarahu Stage, Sheinwoodian, lower Wenlock up to the Ohesaare Stage, upper Přidoli, Silurian.

Ordovician strata on the southeastern Baffin Island shelf revealed by shallow drilling

1977 ◽  
Vol 14 (8) ◽  
pp. 1925-1939 ◽  
Author(s):  
B. MacLean ◽  
L. F. Jansa ◽  
R. K. H. Falconer ◽  
S. P. Srivastava
Keyword(s):  
Organic Material ◽  
Depositional Environments ◽  
Baffin Island ◽  
Island Shelf ◽  
Open Shelf

Cores of the bedrock underlying the southeastern Baffin Island shelf were recovered by underwater electric rock core drill at four localities. Cores from three of the localities consist of olive gray to dark yellow–brown slightly dolomitic limestones, in part burrowed and containing flat pebble conglomerate and breccia. Fragments of trilobites, brachiopods, crinoids, and other fossils including coral are present. Radiolarian wackestone was found at one locality where the rock also contains finely disseminated organic material. The strata have been assigned an Ordovician age (Caradoc) based on identification of chitinozoa, scolecodonts, and coral material. Depositional environments included shallow intertidal–subtidal, open shelf, and outer littoral–epibathyal. Core from the fourth locality is Precambrian biotite gneiss.Seismic reflection and magnetic profiles have been used for correlation of the corehole data and to outline the geology of part of the southeastern Baffin Island shelf.

Tertiary basalts of western Davis Strait: bedrock core samples and geophysical data

1978 ◽  
Vol 15 (5) ◽  
pp. 773-780 ◽  
Author(s):  
B. MacLean ◽  
R. K. H. Falconer ◽  
D. B. Clarke
Keyword(s):  
Magnetic Anomaly ◽  
Seismic Reflection ◽  
Volcanic Rocks ◽  
Geophysical Data ◽  
Baffin Island ◽  
Main Area ◽  
Fine Grained ◽  
Core Samples ◽  
Davis Strait ◽  
Island Shelf

Short bedrock cores of basalt were recovered at two localities on the Baffin Island shelf, 33 and 89 km southeast of Cape Dyer. The volcanic rocks underlying these sites have a surface extent of some 8000 km2 as outlined by seismic reflection and magnetic anomaly profiles. Similar rocks are inferred to occur at two smaller offshore areas south of the main area. The offshore occurrences are both more continuous and much larger than the onshore basalt areas of eastern Baffin Island.The core samples appear to have been cut from single flows consisting of fine-grained microporphyritic basalts with olivine as the principal phenocryst phase. Although having distinct differences from one another in terms of texture and degree of alteration, the samples from the three drill stations bear similarities to the Baffin Island basalts that suggest a close petrogenetic relationship may exist between the onshore and offshore basalts. However, in contrast to the subaqueously erupted volcanic breccias of onshore Baffin Island and West Greenland the offshore samples contain little evidence of glass, suggesting the possibility that the latter may have been erupted in a subaerial environment.

scholarly journals Volume, Freshwater, and Heat Fluxes through Davis Strait, 2004–05*

2011 ◽  
Vol 41 (3) ◽  
pp. 429-436 ◽  
Author(s):  
B. Curry ◽  
C. M. Lee ◽  
B. Petrie
Keyword(s):  
Heat Fluxes ◽  
First Year ◽  
Baffin Island ◽  
Fram Strait ◽  
The West ◽  
Baffin Bay ◽  
Freshwater Fluxes ◽  
Davis Strait ◽  
Island Shelf ◽  
Southward Transport

Abstract Davis Strait volume [−2.3 ± 0.7 Sv (1 Sv ≡ 106 m3 s−1); negative sign indicates southward transport], freshwater (−116 ± 41 mSv), and heat (20 ± 9 TW) fluxes estimated from objectively mapped 2004–05 moored array data do not differ significantly from values based on a 1987–90 array but are distributed differently across the strait. The 2004–05 array provided the first year-long measurements in the upper 100 m and over the shelves. The upper 100 m accounts for 39% (−0.9 Sv) of the net volume and 59% (−69 mSv) of the net freshwater fluxes. Shelf contributions are small: 0.4 Sv (volume), 15 mSv (freshwater), and 3 TW (heat) from the West Greenland shelf and −0.1 Sv, −7 mSv, and 1 TW from the Baffin Island shelf. Contemporaneous measurements of the Baffin Bay inflows and outflows indicate that volume and freshwater budgets balance to within 26% and 4%, respectively, of the net Davis Strait outflow. Davis Strait volume and freshwater fluxes nearly equal those from Fram Strait, indicating that both are significant Arctic freshwater pathways.

scholarly journals Petrograpic and material observations of basaltic lapilli tuff, 1979 and 2017 Surtsey drill cores, Iceland

2020 ◽  
Vol 14 ◽  
pp. 47-62
Author(s):  
Marie D. Jackson
Keyword(s):  
Water Absorption ◽  
Time Lapse ◽  
Dry Density ◽  
High Porosity ◽  
Thin Sections ◽  
Depositional Processes ◽  
Alteration Processes ◽  
Lapilli Tuff ◽  
Microtubular Structures ◽  
Drill Cores

Petrographic studies of thin sections from the 1979 and 2017 Surtsey drill cores provide new insights into microstructural features in basaltic lapilli tuff sampled from the principal structural and hydrothermal zones of the volcano. These describe narrow rims of fine ash on altered glass pyroclasts in thin sections of the 2017 cores, characteristics of granular and microtubular structures in the original thin sections of the 1979 core, and glass alteration in diverse environments. The narrow ash rims follow the outlines of glass pyroclasts in the subaerial tuff cone and in submarine and sub-seafloor deposits; they suggest complex eruptive and depositional processes. The tubular microstructures resemble endolithic microborings in older oceanic basalt; they suggest possible microbial activity. Tubule lengths indicate rapid growth rates, up to 30 µm in ~15 years. Comparisons of glass alteration in thin sections prepared immediately after drilling in 1979 and 2017 indicate differential time-lapse alteration processes in the structural and hydrothermal zones of the volcano. In contrast, thin sections of the 1979 core prepared after 38 years in the repository reveal labile glass alteration during archival storage. The oven-dry density of the sub-seafloor lapilli tuff decreases in 2017 samples with high porosity and water absorption and increases in 2017 samples with a compact ash matrix and lower water absorption. The petrographic descriptions and material measurements provide a foundational reference for further investigations of explosive eruption and deposition of basaltic tephra at Surtsey and the subsequent alteration of these deposits in the volcanic environment and, potentially, the curatorial environment.

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