The origin of the Cambrian−Ordovician tectono-magmatic events affecting NE Gondwana and the adjac... more The origin of the Cambrian−Ordovician tectono-magmatic events affecting NE Gondwana and the adjacent peri-Gondwanan terranes (e.g., Himalaya, Lhasa, Southern Qiangtang, Baoshan, Tengchong, Sibumasu, Helmand, and Karakorum) is controversial. Although its volume is poorly constrained, we propose that an extensive belt of granitic rocks that formed in various pulses between ca. 510 Ma and 460 Ma may represent the remains of a potential silicic large igneous province (LIP), which is referred to here as the Pinghe silicic LIP, with an areal extent of ∼2.5 Mkm2. The putative Pinghe silicic LIP is composed predominantly of S-type granites with subordinate A-type granites and minor intraplate mafic rocks. The recognition of this belt of granitic rocks aids in the refinement of tectonic reconstructions of Gondwana and of models for the rifting of terranes from its northern margin. The Pinghe silicic LIP broadly coincides with the adjacent 511 Ma Kalkarindji LIP in northern Australia, and the...
The Australia-Laurentia connection in the Paleoproterozoic to Mesoproterozoic supercontinent Nuna... more The Australia-Laurentia connection in the Paleoproterozoic to Mesoproterozoic supercontinent Nuna is thought to have initiated by ca. 1.6 Ga when both continents were locked in a proto-SWEAT (southwestern U.S.–East Antarctic) configuration. However, the longevity of that configuration is poorly constrained. Here, we present a new high-quality paleomagnetic pole from the ca. 1.3 Ga Derim Derim sills of northern Australia that suggests Australia and Laurentia were in the same configuration at that time. This new paleopole also supports a connection between Australia and North China and, in conjunction with previously reported data from all continents, indicates that the breakup of Nuna largely occurred between ca. 1.3 and 1.2 Ga.
Geological Society, London, Special Publications, 2020
A supercontinent is generally considered to reflect the assembly of all, or most, of the Earth... more A supercontinent is generally considered to reflect the assembly of all, or most, of the Earth's continental lithosphere. Previous studies have used geological, atmospheric and biogenic ‘geomarkers’ to supplement supercontinent identification. However, there is no formal definition of how much continental material is required to be assembled, or indeed which geomarkers need to be present. Pannotia is a hypothesized landmass that existed in the interval c. 0.65–0.54 Ga and was comprised of Gondwana, Laurentia, Baltica and possibly Siberia. Although Pannotia was considerably smaller than Pangaea (and also fleeting in its existence), the presence of geomarkers in the geological record support its identification as a supercontinent. Using 3D mantle convection models, we simulate the evolution of the mantle in response to the convergence leading to amalgamation of Rodinia and Pangaea. We then compare this supercontinent ‘fingerprint’ to Pannotian activity. For the first time, we show...
In the western Cumberland Basin, Nova Scotia, significant thickening of Westphalian A-B strata to... more In the western Cumberland Basin, Nova Scotia, significant thickening of Westphalian A-B strata towards the axis of the Athol Syncline suggests that development of the syncline coincided with that of the depocentre. This contrasts with stratigraphic relations typical of the Late Paleozoic Maritimes Basin where thinning of Westphalian B strata indicates regional, Late Carboniferous erosion or non-deposition. Post-depositional structural complications within the Athol Syncline include truncation of its southern limb by a near-vertical, east-west zone of strike-slip faulting. This zone, the Athol-Sand Cove Fault Zone (ASCFZ), has been correlated to the west with a complex zone of faulting exposed on the coast of Chignecto Bay where numerous normal, reverse and oblique-slip displacements suggest predominantly brittle deformation and changes in the sense of strike slip. To the east, the ASCFZ splays north into the Springhill coalfield where it is responsible for complex patterns of normal...
The Carboniferous – early Permian plant genus Lesleya is a characteristic component of “dryland f... more The Carboniferous – early Permian plant genus Lesleya is a characteristic component of “dryland floras” that occupied a wide range of moisture-stressed, well-drained environments in tropical regions of Euramerica. Fossil records of Lesleya are almost exclusively found in basinal lowlands. For example, occurrences in Early Pennsylvanian-age, seasonally dry, parautochthonous deposits in basinal lowlands of North America (e.g., Illinois Basin, USA) indicate that Lesleya lived in that region in low-altitude (lowland) paleoenvironments during dry climatic intervals. In this paper, we document the first occurrence of Lesleya during the Carboniferous on the Iberian Massif, in lower Gzhelian (Upper Pennsylvanian) strata of the Douro Carboniferous Basin, in northwestern Portugal. This newly discovered occurrence includes a new species, Lesleya iberiensis sp. nov., recognized on the basis of natural molds of leaves. The Portuguese Lesleya fossils are from upland intramontane deposits and occu...
The Antigonish Basin is one of several Carboniferous structural basins in northeastern Nova Scoti... more The Antigonish Basin is one of several Carboniferous structural basins in northeastern Nova Scotia, the evolution of which have been cited as evidence for major detachment faulting within the Vis. Windsor Group of Maritime Canada. Evidence of extension in the Antigonish Basin takes the form of a major subhorizontal structure that closely follows the basin margins and has been interpreted as part of the regional Ainslie Detachment. Placed at the top of the basal Macumber Formation and reportedly characterized by several metres of calc-mylonite, the detachment is considered to have accommodated 10—25 km of westward transport of the evaporitic Windsor and overlying Mabou groups during the late Namurian-early Westphalian. However, deformation within the Macumber Formation limestone immediately beneath the detachment surface suggests local extension of Vis. age. Recumbent intraformational folds are overlain by depositional breccias that contain previously folded fragments and are themsel...
A 4–m lidar digital elevation model (DEM) provides sufficient resolution to examine the impact of... more A 4–m lidar digital elevation model (DEM) provides sufficient resolution to examine the impact of variable till cover on the incision history of multiple small (5 km2) catchments in eastern Canada. The study site was selected because it has homogeneous bedrock geology that dips parallel to the land surface, is tectonically stable, has undergone common base level changes, and has a common ice history, with variable overburden thickness, from thin cover in the west to thick cover in the east. Basin morphometrics were compared for similar-size basins that have variable till cover thicknesses. Basins with thicker till cover are wider and show differences in hypsometries compared to those where till cover is thin. Two basins representing end members of till thickness were measured for stream discharge and water chemistry. Thick till (> 1 m) on the eastern half of North Mountain retards infiltration sufficiently to promote overland flow and accelerate incision relative to areas with ...
The origin of the Cambrian−Ordovician tectono-magmatic events affecting NE Gondwana and the adjac... more The origin of the Cambrian−Ordovician tectono-magmatic events affecting NE Gondwana and the adjacent peri-Gondwanan terranes (e.g., Himalaya, Lhasa, Southern Qiangtang, Baoshan, Tengchong, Sibumasu, Helmand, and Karakorum) is controversial. Although its volume is poorly constrained, we propose that an extensive belt of granitic rocks that formed in various pulses between ca. 510 Ma and 460 Ma may represent the remains of a potential silicic large igneous province (LIP), which is referred to here as the Pinghe silicic LIP, with an areal extent of ∼2.5 Mkm2. The putative Pinghe silicic LIP is composed predominantly of S-type granites with subordinate A-type granites and minor intraplate mafic rocks. The recognition of this belt of granitic rocks aids in the refinement of tectonic reconstructions of Gondwana and of models for the rifting of terranes from its northern margin. The Pinghe silicic LIP broadly coincides with the adjacent 511 Ma Kalkarindji LIP in northern Australia, and the...
The Australia-Laurentia connection in the Paleoproterozoic to Mesoproterozoic supercontinent Nuna... more The Australia-Laurentia connection in the Paleoproterozoic to Mesoproterozoic supercontinent Nuna is thought to have initiated by ca. 1.6 Ga when both continents were locked in a proto-SWEAT (southwestern U.S.–East Antarctic) configuration. However, the longevity of that configuration is poorly constrained. Here, we present a new high-quality paleomagnetic pole from the ca. 1.3 Ga Derim Derim sills of northern Australia that suggests Australia and Laurentia were in the same configuration at that time. This new paleopole also supports a connection between Australia and North China and, in conjunction with previously reported data from all continents, indicates that the breakup of Nuna largely occurred between ca. 1.3 and 1.2 Ga.
Geological Society, London, Special Publications, 2020
A supercontinent is generally considered to reflect the assembly of all, or most, of the Earth... more A supercontinent is generally considered to reflect the assembly of all, or most, of the Earth's continental lithosphere. Previous studies have used geological, atmospheric and biogenic ‘geomarkers’ to supplement supercontinent identification. However, there is no formal definition of how much continental material is required to be assembled, or indeed which geomarkers need to be present. Pannotia is a hypothesized landmass that existed in the interval c. 0.65–0.54 Ga and was comprised of Gondwana, Laurentia, Baltica and possibly Siberia. Although Pannotia was considerably smaller than Pangaea (and also fleeting in its existence), the presence of geomarkers in the geological record support its identification as a supercontinent. Using 3D mantle convection models, we simulate the evolution of the mantle in response to the convergence leading to amalgamation of Rodinia and Pangaea. We then compare this supercontinent ‘fingerprint’ to Pannotian activity. For the first time, we show...
In the western Cumberland Basin, Nova Scotia, significant thickening of Westphalian A-B strata to... more In the western Cumberland Basin, Nova Scotia, significant thickening of Westphalian A-B strata towards the axis of the Athol Syncline suggests that development of the syncline coincided with that of the depocentre. This contrasts with stratigraphic relations typical of the Late Paleozoic Maritimes Basin where thinning of Westphalian B strata indicates regional, Late Carboniferous erosion or non-deposition. Post-depositional structural complications within the Athol Syncline include truncation of its southern limb by a near-vertical, east-west zone of strike-slip faulting. This zone, the Athol-Sand Cove Fault Zone (ASCFZ), has been correlated to the west with a complex zone of faulting exposed on the coast of Chignecto Bay where numerous normal, reverse and oblique-slip displacements suggest predominantly brittle deformation and changes in the sense of strike slip. To the east, the ASCFZ splays north into the Springhill coalfield where it is responsible for complex patterns of normal...
The Carboniferous – early Permian plant genus Lesleya is a characteristic component of “dryland f... more The Carboniferous – early Permian plant genus Lesleya is a characteristic component of “dryland floras” that occupied a wide range of moisture-stressed, well-drained environments in tropical regions of Euramerica. Fossil records of Lesleya are almost exclusively found in basinal lowlands. For example, occurrences in Early Pennsylvanian-age, seasonally dry, parautochthonous deposits in basinal lowlands of North America (e.g., Illinois Basin, USA) indicate that Lesleya lived in that region in low-altitude (lowland) paleoenvironments during dry climatic intervals. In this paper, we document the first occurrence of Lesleya during the Carboniferous on the Iberian Massif, in lower Gzhelian (Upper Pennsylvanian) strata of the Douro Carboniferous Basin, in northwestern Portugal. This newly discovered occurrence includes a new species, Lesleya iberiensis sp. nov., recognized on the basis of natural molds of leaves. The Portuguese Lesleya fossils are from upland intramontane deposits and occu...
The Antigonish Basin is one of several Carboniferous structural basins in northeastern Nova Scoti... more The Antigonish Basin is one of several Carboniferous structural basins in northeastern Nova Scotia, the evolution of which have been cited as evidence for major detachment faulting within the Vis. Windsor Group of Maritime Canada. Evidence of extension in the Antigonish Basin takes the form of a major subhorizontal structure that closely follows the basin margins and has been interpreted as part of the regional Ainslie Detachment. Placed at the top of the basal Macumber Formation and reportedly characterized by several metres of calc-mylonite, the detachment is considered to have accommodated 10—25 km of westward transport of the evaporitic Windsor and overlying Mabou groups during the late Namurian-early Westphalian. However, deformation within the Macumber Formation limestone immediately beneath the detachment surface suggests local extension of Vis. age. Recumbent intraformational folds are overlain by depositional breccias that contain previously folded fragments and are themsel...
A 4–m lidar digital elevation model (DEM) provides sufficient resolution to examine the impact of... more A 4–m lidar digital elevation model (DEM) provides sufficient resolution to examine the impact of variable till cover on the incision history of multiple small (5 km2) catchments in eastern Canada. The study site was selected because it has homogeneous bedrock geology that dips parallel to the land surface, is tectonically stable, has undergone common base level changes, and has a common ice history, with variable overburden thickness, from thin cover in the west to thick cover in the east. Basin morphometrics were compared for similar-size basins that have variable till cover thicknesses. Basins with thicker till cover are wider and show differences in hypsometries compared to those where till cover is thin. Two basins representing end members of till thickness were measured for stream discharge and water chemistry. Thick till (> 1 m) on the eastern half of North Mountain retards infiltration sufficiently to promote overland flow and accelerate incision relative to areas with ...
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