Emplacement of Continental Flood Basalt Lava Flows

2013 ◽  
pp. 381-410 ◽  
Author(s):  
Stephen Self ◽  
Thorvaldur Thordarson ◽  
Laszlo Keszthelyi
Keyword(s):  
Flood Basalt ◽  
Lava Flows ◽  
Basalt Lava ◽  
Continental Flood Basalt

scholarly journals Thickness Characteristics of Pāhoehoe Lavas in the Deccan Province, Western Ghats, India, and in Continental Flood Basalt Provinces Elsewhere

2021 ◽  
Vol 8 ◽  
Author(s):  
Stephen Self ◽  
Tushar Mittal ◽  
Anne Elizabeth Jay
Keyword(s):  
Columbia River ◽  
Flood Basalt ◽  
Flow Fields ◽  
Lava Flows ◽  
Basalt Lava ◽  
Continental Flood Basalt ◽  
Quantitative Basis ◽  
Simple Flows ◽  
Lava Morphology ◽  
Central Atlantic

Constraining the eruption rates of flood basalt lava flows remains a significant challenge despite decades of work. One potential observable proxy for eruption rates is flood basalt lava-flow lobe thicknesses, a topic that we tackle here quantitatively. In this study, we provide the first global compilation of pāhoehoe lava-lobe thicknesses from various continental flood basalt provinces (∼ 3,800 measurements) to compare characteristic thicknesses within and between provinces. We refer to thin lobes (∼ ≤5 m), characteristic of “compound” lavas, as hummocky pāhoehoe lava flows or flow-fields. Conversely, we term thicker lobes, characteristic of “simple” flows, as coming from sheet-lobe-dominated flows. Data from the Deccan Traps and Columbia River flood-basalt provinces are archetypal since they have the most consistent datasets as well as established chemo- and litho-stratigraphies. Examining Deccan lobe thicknesses, we find that previously suggested (and disputed) distinct temporal and regional distributions of hummocky pāhoehoe and sheet-lobe-dominated flow fields are not strongly supported by the data and that each geochemically defined formation displays both lobe types in varying amounts. Thin flow-lobes do not appear to indicate proximity to source. The modal lobe thickness of Deccan formations with abundant “thin” lava-lobes is 8 m, while the mode for sheet-lobe-dominated formations is only 17 m. Sheet-lobes up to 75–80 m are rare in the Deccan and Columbia River Provinces, and ones >100 m are exceptional globally. For other flood basalt provinces, modal thickness plots show a prevalence toward similar lobe thicknesses to Deccan, with many provinces having some or most lobes in the 5–8 m modal range. However, median values are generally thicker, in the 8–12 m range, suggesting that sheet-lobes dominate. By contrast, lobes from non-flood basalt flow-fields (e.g., Hawai’i, Snake River Plain) show distinctly thinner modes, sub-5 m. Our results provide a quantitative basis to ascertain variations in gross lava morphology and, perhaps, this will in future be related to emplacement dynamics of different flood basalt provinces, or parts thereof. We can also systematically distinguish outlier lobes (or regions) from typical lobes in a province, e.g., North American Central Atlantic Magmatic Province lava-lobes are anomalously thick and are closely related to feeder-intrusions, thus enabling a better understanding of conditions required to produce large-volume, thick, flood basalt lava-lobes and flows.

Geochemical, petrographic, and stratigraphic analyses of the Portage Lake Volcanics of the Keweenawan CFBP: implications for the evolution of Main stage volcanism in Continental Flood Basalt Provinces

2021 ◽  
pp. SP518-2020-221
Author(s):  
W. R. Davis ◽  
M. A. Collins ◽  
T. O. Rooney ◽  
E. L. Brown ◽  
C. A. Stein ◽  
...  
Keyword(s):  
Trace Elements ◽  
Flow Analysis ◽  
Flood Basalt ◽  
Lava Flows ◽  
Rift System ◽  
Main Stage ◽  
Continental Flood Basalt ◽  
Content Type ◽  
Supplementary Material ◽  
Incompatible Trace Elements

AbstractContinental Flood Basalt Provinces (CFBPs) are large igneous features formed by the extrusion of massive amounts of lavas that require significant evolution within the lithosphere. Although sequential lava flows are effective probes of magmatic systems, CFBPs are typically poorly preserved. We focus on lava flows from the well-preserved 1.1 Ga Keweenawan CFBP that erupted within the Midcontinent Rift System. We present a new geochemical, petrographic, and stratigraphic synthesis from the Main stage Portage Lake Volcanics (PLV). Flow-by-flow analysis of the PLV reveals that major element behavior is decoupled from trace element behavior; MgO exhibits limited variability, while compatible and incompatible trace elements deviate from high to low concentrations throughout the sequence. The concentrations of incompatible trace elements slightly decrease from the base of the sequence to the top. We investigate these observations by applying a recharge, evacuation, assimilation, and fractional crystallization model to geochemical and petrographic data. Our modelling demonstrates a magmatic system experiencing increased evacuation rates while fractionation and assimilation rates decrease, indicating an increase in magmatic flux. The outcome of this modelling is a progressively more efficient magma system within the PLV. This study highlights the utility of joint petrographic and geochemical interpretation in constraining CFBP magma evolution.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5424758

scholarly journals Reconstructing flood basalt lava flows in three dimensions using terrestrial laser scanning

Geosphere ◽  
2011 ◽  
Vol 7 (1) ◽  
pp. 87-96 ◽  
Author(s):  
C. E. Nelson ◽  
D. A. Jerram ◽  
R. W. Hobbs ◽  
R. Terrington ◽  
H. Kessler
Keyword(s):  
Laser Scanning ◽  
Terrestrial Laser Scanning ◽  
Flood Basalt ◽  
Lava Flows ◽  
Three Dimensions ◽  
Basalt Lava

Recycling of Flow-Top Breccia Crusts into Molten Interiors of Flood Basalt Lava Flows: Field and Geochemical Evidence from the Deccan Traps

2010 ◽  
pp. 161-180 ◽  
Author(s):  
Hetu C. Sheth ◽  
Jyotiranjan S. Ray ◽  
P. Senthil Kumar ◽  
Raymond A. Duraiswami ◽  
Rudra Narayan Chatterjee ◽  
...  
Keyword(s):  
Flood Basalt ◽  
Deccan Traps ◽  
Lava Flows ◽  
Basalt Lava ◽  
Geochemical Evidence
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