scholarly journals Lithofacies from the 1963-1967 Surtsey eruption in SUSTAIN drill cores SE-2a, SE-2b and SE-03

2020 ◽  
Vol 14 ◽  
pp. 19-32
Author(s):  
Jocelyn McPhie ◽  
James D.L. White ◽  
Carolyn Gorny ◽  
Marie D. Jackson ◽  
Magnús Tumi Gudmundsson ◽  
...  
Keyword(s):  
Hydrothermal Alteration ◽  
Sedimentary Facies ◽  
Drill Hole ◽  
Explosive Eruptions ◽  
Volcanic System ◽  
Sea Floor ◽  
Alteration Processes ◽  
Lapilli Tuff ◽  
Drill Holes ◽  
Drill Cores

Surtsey was drilled in 2017 in the context of the Surtsey Underwater volcanic System for Thermophiles, Alteration processes and INnovative Concretes (SUSTAIN) project. Vertical drill holes, SE-02a and SE02b (drilled to 191.64 m), and angled drill SE-03 (drilled to 354.05 m), intersected armoured lapilli tuff and lapilli tuff generated mainly by explosive eruptions at Surtur from November 1963 to January 1964. The top ~20 m of lapilli tuff was erupted from Surtungur. Intervals of coherent basalt in SE-02b (15.7 to 17 m and <15 cm at the end) and in SE-03 (<1 m at ~60 m and ~238 m, and 10 m near the base) are probably intrusions that may have fed the small lavas erupted at Surtur ~2.5 years later. Although collared only a few m from the 1979 drill hole, neither SE-02a nor SE-02b intersected the 13-m-thick interval of basalt found in the 1979 drill hole. The 2017 drill cores are entirely lithified and variably altered, reflecting the effects of hydrothermal alteration and cement deposition on the originally fresh, unconsolidated ash and lapilli. Drill hole SE-03 was drilled on an azimuth of 264o and at 55o from horizontal, obliquely crossing the crater- and conduit-fill of Surtur. Although the exact trajectory of SE-03 is unknown (the drill hole was not surveyed), the drill hole ended at a vertical depth of ~100 m below the pre-eruption sea floor, however, sedimentary facies known to underlie the sea floor nearby were not intersected. Surtur eruptions therefore excavated the pre-eruption sea floor to a depth of several tens of m.

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.

PATTERNS OF GASTROPOD MOLLUSK PREDATION ON BIVALVE MOLLUSKS ALONG THE UPPER TEXAS GULF COAST

2018 ◽  
Vol 70 (1) ◽  
Author(s):  
Serena J. Randolph ◽  
Alan D. Maccarone
Keyword(s):  
Shell Thickness ◽  
Prey Species ◽  
Gulf Coast ◽  
Prey Selection ◽  
Drill Hole ◽  
The United States ◽  
Hole Diameter ◽  
Bivalve Mollusks ◽  
Collection Site ◽  
Drill Holes

Abstract Predation on bivalve mollusks by gastropod mollusks is common in coastal regions of the United States; however, few previous studies have examined whether drilling gastropods exhibit prey selection. In 2016, shells with small holes drilled by as many as two gastropod predators were collected at three sites separated by 30 km along the Texas Upper Gulf Coast on the Bolivar Peninsula (29° 40′N, 94° 90′W). The likeliest predators in these waters are the southern oyster drill (Stramonita haemastoma Linnaeus 1767) and the moon snail (Neverita duplicate Say 1822). Collected shells were identified to species and measurements were taken to examine statistical relationships between predators and prey species. These measurements included drill-hole diameter, shell thickness, drill-hole completeness, number of drill attempts, and collection site. Across the three locations, 17 different species of shells with drill holes were collected; of these, we focused on the ten most abundant species (n = 277 shells). The sample showed high variation in drill-hole diameter, shell thickness, and drill-hole completeness. Both the total number of holes and mean drill-hole diameter differed significantly among prey species (ANOVA, both P &lt; 0.0001). In addition, drill-hole diameter correlated directly with prey shell thickness (P &lt; 0.0001). Shells whose drill holes were complete were significantly thinner than shells with incomplete holes (P &lt; 0.0001). Mean prey shell thickness, mean drill-hole diameter, and mean number of drill holes all differed significantly by collection site (all P &lt; 0.0001). Ecological and morphological implications related to gastropod predation on mollusks are discussed.

scholarly journals Hydrothermal alteration mineralogy of SOH drill holes, Kilauea East Rift Zone geothermal area, Hawaii

1996 ◽  
Author(s):  
Keith E. Bargar ◽  
Terry E.C. Keith ◽  
Frank A. Trusdell ◽  
S.R. Evans ◽  
M.L. Sykes
Keyword(s):  
Hydrothermal Alteration ◽  
Rift Zone ◽  
Geothermal Area ◽  
Drill Holes

Eruptive frequency of the Bora-Baricha-Tullu Moye (BBTM) volcanic system in the Central Main Ethiopian Rift

2021 ◽  
Author(s):  
Amdemichael Zafu Tadesse ◽  
Karen Fontijn ◽  
Abate Assen Melaku ◽  
Ermias Filfilu Gebru ◽  
Victoria Smith ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Volcanic Eruptions ◽  
Volcanic Field ◽  
Tectonic Activity ◽  
Explosive Eruptions ◽  
Ethiopian Rift ◽  
Rift System ◽  
Diagnostic Features ◽  
Volcanic System ◽  
Main Ethiopian Rift

&lt;p&gt;The Main Ethiopian Rift (MER) is the northern portion of the East African Rift System and separates the Eastern and Western plateaus of Ethiopia. The recent volcanic and tectonic activity is largely focused within the rift basin along a 20 km wide zone on the rift floor. Large silicic volcanic complexes are aligned along this central rift axis but their eruptive histories are not well constrained.&lt;/p&gt;&lt;p&gt;The Bora-Baricha-Tullu Moye (BBTM) volcanic field is situated in the central Main Ethiopian Rift and has a different appearance than the other MER volcanic systems. The BBTM constitutes several late Quaternary edifices, the major ones are: Tullu Moye, Bora and Baricha. In addition, there are multiple smaller eruptive vents (e.g. Oda and Dima), cones, and domes across the ca. 20 X 20 km wide area. Currently, there is very little information on the frequency and magnitude of past volcanic eruptions. We present a new dataset of field observations, componentry, petrography, geochronology (&lt;sup&gt;40&lt;/sup&gt;Ar/&lt;sup&gt;39&lt;/sup&gt;Ar), and glass major and trace element chemistry. The data are assessed as potential fingerprints to assign diagnostic features and correlate units across the area, and establish a tephrostratigraphic framework for the BBTM volcanic field.&lt;/p&gt;&lt;p&gt;Two large-volume and presumably caldera-forming eruptions are identified, the younger of which took place at 100 ka. The volcanic products exposed in the BBTM area show that the volcanic field has undergone at least 20 explosive eruptions since then. The post-caldera eruptions have comenditic (Tullu Moye) and pantelleretic (Bora and Baricha) magma compositions. Other smaller edifices such as Oda and Dima also erupted pantelleritic magmas, and only differ slightly in composition than tephra of Bora and Baricha. Tullu Moye had two distinct explosive eruptions that dispersed tephra up to 14 km away and on to the eastern plateau. Bora and Baricha together had at least 8 explosive eruptions. Their deposits can be distinguished by their light grey color and unique lithic components. Oda had 7 eruptions, the most recent of which generated a pyroclastic density current that travelled up to 10 km away from the vent. Dima experienced at least 3 eruptions, generating tephra with a bluish-grey colour.&lt;/p&gt;&lt;p&gt;This mapping and compositional analysis of the deposits from the BBTM in the MER indicates that the region has been more active in the last 100 ka than previously thought, which has implications for hazards assessments for the region.&lt;/p&gt;

Large Drill Holes Are Still Present in the Long Term After Arthroscopic Bankart Repair With Absorbable Tacks: An 18-Year Randomized Prospective Study

2020 ◽  
Vol 48 (8) ◽  
pp. 1865-1872
Author(s):  
Christina Chrysanthou Constantinou ◽  
Ninni Sernert ◽  
Lars Rostgård-Christensen ◽  
Jüri Kartus
Keyword(s):  
Study Groups ◽  
Drill Hole ◽  
Ct Images ◽  
Bankart Repair ◽  
Plain Radiographs ◽  
Arthroscopic Bankart Repair ◽  
Absorbable Tacks ◽  
Drill Holes

Background: Studies have demonstrated the development of an osseous reaction at the drill sites of anchors after arthroscopic shoulder surgery. Purpose: To investigate the drill-hole size at 18 years after arthroscopic Bankart repair using either fast polygluconate acid (PGA) or slow polylevolactic acid (PLLA) absorbable tacks and to compare the functional outcomes and development of osteoarthritis. Study design: Randomized controlled trial; Level of evidence, 2. Methods: 40 patients with unidirectional anterior shoulder instability, treated with arthroscopic Bankart repair, were randomized into the PGA group (n = 20) or the PLLA group (n = 20). Plain radiographs of both shoulders, as well as computed tomography (CT) images of the operated shoulder, were used to evaluate the drill-hole size, volume, and degenerative changes. Functional outcomes were assessed by use of the Rowe score, Constant score, and Western Ontario Shoulder Instability (WOSI) index. Results: Of the 40 patients, 32 patients returned for the follow-up (15 PGA and 17 PLLA). No significant differences were found in the population characteristics between the study groups. The mean follow-up time was 18 years for both groups. No significant differences were seen in range of motion, strength in abduction, or Constant, Rowe, and WOSI scores between the groups. Recurrence rate was 33% in the PGA group and 6% in the PLLA group during the follow-up period ( P = .07). The drill-hole appearance on plain radiographs (invisible/hardly visible/visible/cystic) was 11/2/2/0 and 6/5/5/1 for the PGA and PLLA groups, respectively ( P = .036). The mean ± SD drill-hole volume as estimated on CT images was 89 ± 94 and 184 ± 158 mm3 in the PGA and PLLA groups, respectively ( P = .051). Degenerative changes (normal/minor/moderate/severe) on plain radiographs were 7/4/4/0 and 3/8/5/1 for the PGA and PLLA groups, respectively ( P = .21), and on CT images were 5/7/3/0 and 2/6/6/3 for the PGA and PLLA groups, respectively ( P = .030). Conclusion: This long-term follow-up study demonstrated that the PLLA group had significantly more visible drill holes than the PGA group on plain radiographs. However, this difference was not evident on CT imaging, with both groups having several visible cystic drill holes and a substantial drill-hole volume defect. No significant differences were found between the study groups in terms of clinical outcomes.

Investigation of Drill Hole Quality of Multi-Layer PWBs for High Current Capacity

2007 ◽  
Author(s):  
Eiichi Aoyama ◽  
Toshiki Hirogaki ◽  
Keiji Ogawa ◽  
Kenichi Mori ◽  
Yuusuke Itagaki
Keyword(s):  
Copper Foil ◽  
Drill Hole ◽  
Foil Thickness ◽  
Electronic Systems ◽  
Hole Quality ◽  
Large Current ◽  
Drill Holes ◽  
Objective Variable ◽  
Chip Load ◽  
Through Hole

Recently, as a result of changes in the automotive industry, a large number of electronic systems have been installed in cars. The thickness of the copper foil used for printed wiring boards (PWBs) has tended to increase in response to the large current capacity required for such electronic equipment. Therefore, the nail head generated in the inner layer copper foil was examined with respect to the influence of the thickness of the copper foil on the through-hole quality. In the present study, the size of the nail head generated in the copper foil after drilling a through hole was used as the objective variable. The explaining variables included drill wear, frequency, feed rate, chip load, drill temperature, copper foil thickness, copper foil cutting distance, and number of drill holes. We investigated the relationships between these explaining variables and the objective variable and found that the copper foil cutting distance was a very important parameter in generating nail heads. In addition, we found that the chip load is important for controlling nail head generation.

Auriferous chert, banded iron formation, and related volcanogenic hydrothermal alteration, Atik Lake, Manitoba

1989 ◽  
Vol 26 (12) ◽  
pp. 2676-2690 ◽  
Author(s):  
Louis R. Bernier ◽  
Wallace H. MacLean
Keyword(s):  
Hydrothermal Alteration ◽  
Earth Element ◽  
Massive Sulfide ◽  
Iron Formation ◽  
Small Scale ◽  
Banded Iron Formation ◽  
Sulfide Deposits ◽  
Sea Floor ◽  
Facies Metamorphism ◽  
Altered Basalt

Small-scale alteration pipes and stratiform alteration in Archean glomeroporphyritic tholeiitic basalts at Atik Lake, Manitoba, stratigraphically underlie silicate-oxide banded iron formation (BIF) and auriferous sulfide-bearing chert. The auriferous chert is locally interbedded with graphitic argillite, indicating euxinic conditions during deposition. Cordierite–gedrite rocks formed by recrystallization of alteration assemblages during the lower amphibolite-facies metamorphism (T = 550 °C, P = 2.5 kbar). Al2O3, TiO2, Zr, and Nb, which were relatively immobile during alteration, have been used to monitor igneous differentiation and alteration. Volcanogenic hydrothermal alteration resulted in depletion of Ca, Si, Mg, Na, and Sr in the altered basalt and the addition of K, Fe, Rb, and Ba. This was accompanied by mass and volume losses of up to 25%. The mineralizing fluid was reducing and somewhat acidic. Rare-earth-element (REE) profiles of BIF and graphitic argillite, normalized to Archean shale, are less steep ((La/Lu)N = 0.51 and 0.49 respectively), than those of both mineralized chert ((La/Lu)N = 0.04) and recent sea-floor, siliceous, gold-enriched massive sulfides ((La/Lu)N = 0.11). REE profiles and Boström's plot suggest that the auriferous, sulfide-bearing chert formed by mixing of hydrothermal and detrital components. The overall chemical changes in the Atik Lake alteration system are comparable to those in Noranda-type massive-sulfide deposits. The trace-metal association in the auriferous chert is similar to that at some modern sea-floor hydrothermal sites.

The Iceland Research Drilling Project crustal section: stable remagnetization below 3 km crustal depth

1988 ◽  
Vol 25 (8) ◽  
pp. 1304-1315 ◽  
Author(s):  
James M. Hall ◽  
Brian E. Fisher
Keyword(s):  
Grain Size ◽  
Hydrothermal Alteration ◽  
Remanent Magnetization ◽  
Drill Hole ◽  
Lava Flows ◽  
Crustal Layer ◽  
Transition Zones ◽  
Mixed Polarity ◽  
History Of ◽  
Drilling Project

A section at below 3.1 km depth in Icelandic crust, sampled in the 1978 Icelandic Research Drilling Project drill hole, contains a number of subaerially deposited lava flows showing both downwards and probably original upwards inclinations of cleaned, stable remanent magnetization. Such "mixed polarities" are inconsistent with an initial cooling thermoremanent origin for the magnetization. An attempt is made to identify the factors involved in producing these mixed polarities and to consider the possible wider importance of the results. The mixed-polarity flows have experienced intense hydrothermal alteration, followed by the widespread deposition of secondary magnetite. Secondary magnetite, which is formed in relatively anhydrous conditions associated with dike intrusion, dominates primary magnetite volumetrically where dike density locally exceeds about 30%.Where secondary magnetite is very dominant or is the only type of magnetite present, directional remagnetization appears to be uniform and complete. Where secondary and primary magnetite are both important, relatively high remanence and saturation magnetizations, total magnetite and primary magnetite grain size, and low deuteric oxidation state of primary magnetite are all associated with downwards directional remagnetization. It appears that a complex balance of the properties and history of primary and secondary magnetite, in addition to the relative abundances of these phases, controls the final stable polarity of samples.If the narrow transition zones between little-altered extrusives, greenschist-facies flows and dikes of the Troodos (Cyprus) ophiolite, and DSDP hole 504B are typical of oceanic crust, a narrow ~0.2 km interval of mixed polarities may be underlain in some locations by an intermediate crustal layer in polarity opposition with the uppermost, little-altered, extrusive layer.

Sign in / Sign up

Export Citation Format

Share Document