scholarly journals Sedimentary and tectonic setting of a mass-transport slope deposit in the Halifax Group, Halifax Peninsula, Nova Scotia, Canada

2015 ◽  
Vol 51 (1) ◽  
pp. 084 ◽  
Author(s):  
John W.F. Waldron ◽  
Rebecca A. Jamieson ◽  
Hayley D. Pothier ◽  
Chris E. White
Keyword(s):  
Nova Scotia ◽  
Mass Transport ◽  
Tectonic Setting ◽  
Tectonic Deformation ◽  
Font Size ◽  
Fine Grained ◽  
Metasedimentary Rocks ◽  
Internal Structures ◽  
Transport Direction ◽  
Deformation Features

<p align="LEFT">Fine-grained metasedimentary rocks of the Halifax Group in southern mainland Nova Scotia can be subdivided into mappable units. In Halifax Peninsula, sulphide-rich hornfels, black slate, metasiltstone, and metasandstone of the Cunard Formation are overlain by grey metasedimentary rocks with abundant cross-laminations and local carbonate and calc-silicate concretions, assigned to the Bluestone Quarry Formation. No fossils are known from the Bluestone Quarry Formation but lithological correlatives elsewhere are Tremadocian. The Bluestone Quarry Formation is here divided into four members. The lowest (Point Pleasant member) contains thin parallel-laminated and cross-laminated <span style="font-family: MinionPro-Regular; font-size: small;"><span style="font-family: MinionPro-Regular; font-size: small;">metasandstone beds with Bouma T</span></span><span style="font-family: MinionPro-Regular; font-size: xx-small;"><span style="font-family: MinionPro-Regular; font-size: xx-small;">bcde </span></span><span style="font-family: MinionPro-Regular; font-size: small;"><span style="font-family: MinionPro-Regular; font-size: small;">and T</span></span><span style="font-family: MinionPro-Regular; font-size: xx-small;"><span style="font-family: MinionPro-Regular; font-size: xx-small;">cde </span></span><span style="font-family: MinionPro-Regular; font-size: small;"><span style="font-family: MinionPro-Regular; font-size: small;">structures, and thicker beds with Bouma ‘a’ divisions. The Black Rock </span></span>Beach member lacks the thicker massive beds and is dominated by rippled and cross-laminated metasedimentary rocks. The overlying Chain Rock member, an erosion-resistant ridge-forming unit, is disrupted by folds and boudinage. Bedding is truncated at the upper contact, and the internal structures are overprinted by (and therefore predate) the Neoacadian cleavage. They are interpreted as products of synsedimentary mass transport. Scarce folds in the Chain Rock member and current ripples in the underlying unit are consistent with a N or NW transport direction. The overlying Quarry Pond member consists of thinly bedded coherent metasedimentary rocks that generally resemble those of the Black Rock Beach member. Although there are indications of upward shallowing in equivalent successions elsewhere in the Halifax Group, the presence of a major mass transport deposit in the Bluestone Quarry Formation shows that this part of the Halifax Group was deposited on a submarine paleoslope. The failure of geologists to identify this feature in much-visited outcrops testifies to the difficulty of identifying synsedimentary deformation features that have been overprinted by later tectonic deformation.</p>

The Lower Cretaceous Chaswood Formation in southern New Brunswick: provenance and tectonics

2007 ◽  
Vol 44 (5) ◽  
pp. 665-677 ◽  
Author(s):  
David JW Piper ◽  
Georgia Pe-Piper ◽  
Thian Hundert ◽  
D V Venugopal
Keyword(s):  
Nova Scotia ◽  
New Brunswick ◽  
Lower Cretaceous ◽  
Tectonic Setting ◽  
Mineral Chemistry ◽  
Source Rocks ◽  
Heavy Minerals ◽  
Metasedimentary Rocks ◽  
South Central ◽  
Tectonic Style

The most northwesterly outcrop of Lower Cretaceous Chaswood Formation is in a pit at Vinegar Hill, south of Sussex, New Brunswick. New mapping and boreholes show thick, fluvial, loosely lithified conglomerates and lesser sandstones unconformably overlying 12 m of mudstone in a 1 km2 basin bounded to the northwest by the Clover Hill fault. Sparse paleocurrent indicators to the southwest parallel this fault. The tectonic setting is similar to that of the Chaswood Formation in the fault-bounded Elmsvale basin in Nova Scotia. In both cases, a basal unit is paraconformable on underlying upper Mississippian rocks, was folded into a syncline within which a middle unit accumulated and was further deformed, and is capped by thin flat-lying sandstone and conglomerate. The tectonic style of the Chaswood Formation at Vinegar Hill demonstrates that early Cretaceous deformation was widespread in the southern Maritimes. Gravel clasts consist overwhelmingly of vein quartz, but sparse lithic clasts match source rocks in south-central New Brunswick. Heavy minerals are mostly ilmenite (40%–70%) and staurolite (20%–40%), with monazite, zircon, and andalusite more abundant than at other Chaswood Formation localities. Heavy mineral chemistry and monazite geochronology suggest a provenance from Silurian metasedimentary rocks and tourmaline granites in central New Brunswick. Different mineral assemblages from the Chaswood Formation in Nova Scotia suggest that an ancestral St. John River drained western New Brunswick and supplied sediment to the Shelburne delta of the Scotian basin.

scholarly journals New seismological data from the Calabrian arc reveal arc-orthogonal extension across the subduction zone

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tiziana Sgroi ◽  
Alina Polonia ◽  
Graziella Barberi ◽  
Andrea Billi ◽  
Luca Gasperini
Keyword(s):  
Lateral Displacement ◽  
Tectonic Setting ◽  
Plate Boundary ◽  
Velocity Model ◽  
Tectonic Deformation ◽  
Accretionary Wedge ◽  
Tectonic Structures ◽  
Plate Convergence ◽  
Seismogenic Layer ◽  
Regional Tectonic

AbstractThe Calabrian Arc subduction-rollback system along the convergent Africa/Eurasia plate boundary is among the most active geological structures in the Mediterranean Sea. However, its seismogenic behaviour is largely unknown, mostly due to the lack of seismological observations. We studied low-to-moderate magnitude earthquakes recorded by the seismic network onshore, integrated by data from a seafloor observatory (NEMO-SN1), to compute a lithospheric velocity model for the western Ionian Sea, and relocate seismic events along major tectonic structures. Spatial changes in the depth distribution of earthquakes highlight a major lithospheric boundary constituted by the Ionian Fault, which separates two sectors where thickness of the seismogenic layer varies over 40 km. This regional tectonic boundary represents the eastern limit of a domain characterized by thinner lithosphere, arc-orthogonal extension, and transtensional tectonic deformation. Occurrence of a few thrust-type earthquakes in the accretionary wedge may suggest a locked subduction interface in a complex tectonic setting, which involves the interplay between arc-orthogonal extension and plate convergence. We finally note that distribution of earthquakes and associated extensional deformation in the Messina Straits region could be explained by right-lateral displacement along the Ionian Fault. This observation could shed new light on proposed mechanisms for the 1908 Messina earthquake.

Geochemistry of the Namurian Lismore Formation, northern mainland Nova Scotia: sedimentation and tectonic activity along the southern flank of the Maritimes Basin

1999 ◽  
Vol 36 (10) ◽  
pp. 1655-1669 ◽  
Author(s):  
Jacquelyn E Stevens ◽  
J Brendan Murphy ◽  
Fred W Chandler
Keyword(s):  
Nova Scotia ◽  
Tectonic Activity ◽  
Isotopic Data ◽  
Rock Fragments ◽  
Metasedimentary Rocks ◽  
Clastic Rocks ◽  
Granitoid Rocks ◽  
Maritimes Basin ◽  
Group B ◽  
Southern Flank

Geochemical and isotopic data from the clastic rocks of the Namurian Lismore Formation in mainland Nova Scotia identify key episodes of tectonic activity during the development of the Maritimes Basin in Atlantic Canada. The Lismore Formation forms part of the Mabou Group and is an upward-coarsening 2500 m thick fluvial sequence deposited in the Merigomish sub-basin along the southern flank of the Maritimes Basin. Based on stratigraphic evidence, the Lismore Formation can be divided into upper and lower members which reflect variations in depositional environment and paleoclimate. The geochemical and isotopic data may also be subdivided into two groupings that primarily reflect varying contributions from accessory phases, clay minerals, or rock fragments. This subdivision occurs 115 m above the base of the upper member. The data from the lower grouping (group A) show an important contribution from underlying Silurian rocks, with a relatively minor contribution from Late Devonian granitoid rocks from the adjacent Cobequid Highlands and possibly metasedimentary rocks from the Meguma Terrane to the south. The data from the upper grouping (group B) reveal a more important contribution from the Cobequid Highlands granitoid rocks. This variation in geochemistry is thought to constrain the age of renewed motion and uplift along the faults along the southern flank of the Maritimes Basin and, more generally, suggests that geochemical and isotopic data of continental clastic rocks may help constrain the age of tectonic events that influence deposition of basin-fill rocks.

scholarly journals Synchrotron radiation X-ray tomographic microscopy (SRXTM) of brachiopod shell interiors for taxonomy: Preliminary report

2010 ◽  
pp. 109-117 ◽  
Author(s):  
Neda Motchurova-Dekova ◽  
David Harper
Keyword(s):  
Synchrotron Radiation ◽  
Three Dimensional ◽  
X Rays ◽  
X Ray ◽  
Fine Grained ◽  
Internal Structures ◽  
Efficient Alternative ◽  
Micro Tomography ◽  
Light Beams ◽  
Non Destructive

Synchrotron radiation X-ray tomographic microscopy (SRXTM) is a non-destructive technique for the investigation and visualization of the internal features of solid opaque objects, which allows reconstruction of a complete three-dimensional image of internal structures by recording of the differences in the effects on the passage of waves of energy reacting with those structures. Contrary to X-rays, produced in a conventional X-ray tube, the intense synchrotron light beams are sharply focused like a laser beam. We report encouraging results from the use of SRXTM for purely taxonomic purposes in brachiopods: an attempt to find a non-destructive and more efficient alternative to serial sectioning and several other methods of dissection together with the non-destructive method of X-ray computerised micro-tomography. Two brachiopod samples were investigated using SRXTM. In ?Rhynchonella? flustracea it was possible to visualise the 3D shape of the crura and dental plates. In Terebratulina imbricata it was possible to reveal the form of the brachidium. It is encouraging that we have obtained such promising results using SRXTM with our very first two fortuitous samples, which had respectively fine-grained limestone and marl as infilling sediment, in contrast to the discouraging results communicated to us by some colleagues who have tested specimens with such infillings using X-ray micro-tomography. In future the holotypes, rare museum specimens or delicate Recent material may be preferentially subjected to this mode of analysis.

scholarly journals Directional expressions cross-linguistically: Nanosyntax and lexicalization

Nordlyd ◽  
2010 ◽  
Vol 36 (1) ◽  
pp. pp
Author(s):  
Marina Pantcheva
Keyword(s):  
Syntactic Structure ◽  
Spatial Domain ◽  
Font Size ◽  
Fine Grained

<!--[if gte mso 10]> <mce:style><! /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Vanlig tabell"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} > <! [endif] > <p class="MsoNormal"><span lang="EN-US">In this paper, I investigate the syntactic structure underlying expressions of the three main types of Paths: Goal Path, Source Path and Route Path. I suggest that they are structurally different and propose a fine-grained syntactic structure for each of them, which is able to account for their morphological make-up. I explore how this structure is spelled out in various languages and show that a nanosyntactic approach to lexicalization captures the facts in an elegant way. In discussing the spell-out of the structure by prepositions and case affixes, I reach the conclusion that sometimes the verb has to &lsquo;reach down&rsquo; and lexicalize heads which belong to the spatial domain (cf. Svenonius and Son 2008). I provide evidence from languages where I argue that this is the case.</span><-->

Dinosaur trackways from the Upper Cretaceous Oldman and Dinosaur Park formations (Belly River Group) of southern Alberta, Canada, reveal novel ichnofossil preservation style

2015 ◽  
Vol 52 (8) ◽  
pp. 630-641 ◽  
Author(s):  
François Therrien ◽  
Darla K. Zelenitsky ◽  
Annie Quinney ◽  
Kohei Tanaka
Keyword(s):  
Natural Area ◽  
Geochemical Composition ◽  
Fine Grained ◽  
Depositional Settings ◽  
Internal Structures ◽  
Southern Alberta ◽  
Dinosaur Tracks ◽  
Geochemical Analyses ◽  
Water Saturated ◽  
Mineralogical Compositions

Dinosaur tracksites recently discovered in exposures of the Belly River Group in the Milk River Natural Area (MRNA) and Dinosaur Provincial Park (DPP) of southern Alberta represent a novel type of ichnofossils. The tracks, all referable to hadrosaurs, occur as sideritic or calcareous concretions protruding above fine-grained deposits and are here termed concretionary tracks. Detailed sedimentological, petrographic, and geochemical analyses reveal that, although the MRNA and DPP tracks are of different mineralogical compositions (calcium carbonate versus siderite, respectively), they display similar internal structures (microscopic convoluted laminations) and occur in depositional settings indicative of wet paleoenvironments, where the ground was soft and water saturated. These characteristics suggest that concretionary tracks are footprint casts that formed as groundwater rich in dissolved carbonates flooded depressions left in the soft substrate. As the ponded water evaporated, minerals began to precipitate and mix with clastic material transported into the depressions, settling as finely laminated mud within the tracks and filling them either completely or partially. The geochemical composition of the precipitate would depend on the prevalent groundwater conditions (e.g., pH, dissolved carbonate and sulphate concrentrations). Cementation of the tracks occurred relatively soon after burial (<100 years), possibly in response to microbial activity and saturation by mineral-rich groundwater, and modern erosion exposed the concretionary tracks by removing the softer host unit. Recognition of this novel type of ichnofossils suggests dinosaur tracks may be more common than previously thought. Unfortunately, concretionary tracks tend to break apart rapidly when the encasing and underlying substrate erodes away, altering their diagnostic shape and rendering them indistinguishable from nonichnogenic concretions. As such, concretionary tracks may be transient ichnofossils in the badlands, explaining why they are rarely recognized.

scholarly journals Evaluation of crustal inhomogeneity parameters in the southern Longmenshan fault zone and adjacent regions

2020 ◽  
Vol 24 (6) ◽  
pp. 1175-1188
Author(s):  
Xiao-Ping Fan ◽  
Yi-Cheng He ◽  
Cong-Jie Yang ◽  
Jun-Fei Wang
Keyword(s):  
Fault Zone ◽  
Lower Crust ◽  
Tectonic Deformation ◽  
Upper Crust ◽  
Crust And Upper Mantle ◽  
Study Region ◽  
Waveform Data ◽  
Longmenshan Fault Zone ◽  
Deformation Features ◽  
Longmenshan Fault

AbstractBroadband teleseismic waveform data from 13 earthquakes recorded by 70 digital seismic stations were selected to evaluate the inhomogeneity parameters of the crustal medium in the southern Longmenshan fault zone and its adjacent regions using the teleseismic fluctuation wavefield method. Results show that a strong inhomogeneity exists beneath the study region, which can be divided into three blocks according to its structure and tectonic deformation features. These are known as the Sichuan-Qinghai Block, the Sichuan-Yunnan Block, and the Mid-Sichuan Block. The velocity fluctuation ratios of the three blocks are approximately 5.1%, 3.6%, and 5.1% in the upper crust and 5.1%, 3.8%, and 4.9% in the lower crust. The inhomogeneity correlation lengths of the three blocks are about 10.1 km, 14.0 km, and 10.7 km in the upper crust and 11.8 km, 17.0 km, and 11.8 km in the lower crust. The differences in the crustal medium inhomogeneity beneath the Sichuan-Yunnan Block, the Sichuan-Qinghai Block, and the Mid-Sichuan Block may be related to intensive tectonic movement and material flow in the crust and upper mantle.

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