Transition from Vertical to Lateral Diking at the Neutral Buoyancy Line
Bibliographic record
Abstract
Buoyant hydraulic fractures (HF) are a viable approach to model propagating magmatic intrusions in the lithosphere. Solutions for fully planar three-dimensional (3D) HF suggest the existence of a family of solutions as a function of fluid and solid properties [1]. Theoretically, such buoyant fractures ascent in a self-sustained manner if no heterogeneities exist.We investigate the presence of a neutral buoyancy line (NBL) as a possible arrest mechanism of such buoyant self-sustained fractures. The NBL stems from a change in solid density and leads to a reversed buoyancy. In other words, the rock density in the upper layer is smaller than the density of the fluid, whereas the inverse is true in the lower layer (see figure 1). When a vertically propagating dike encounters this kind of heterogeneity, three outcomes are possible: The fracture can laterally spread along the NBL, arrest without lateral propagation and possibly initiate an intermediate magma chamber, or “burst” through the upper layer and become a feeder dike.We focus on the first two possible outcomes and exclude the emergence of feeder dikes. Using numerical simulations, we delimit the conditions distinguishing the arrest from lateral spreading and characterize the transition from vertical to lateral dike propagation under various conditions.Our simulations emphasize the dependence of lateral diking on the ratio between the total volume release and a limiting, minimal volume required for the emergence of self-sustained vertical dikes [2, 3, 4]. If the release volume is sufficient, the dike spreads laterally along the NBL. In the resulting horizontal intrusion, two-dimensional (2D) solutions of horizontal cross-sections in the viscosity- [5] and the toughness-dominated regime emerge. The emergence of the respective limits strongly correlates with the depth of the source magma chamber, a problem parameter we vary to compare simulation results with observations from lateral dike rifting intrusions. In particular, we discuss if these rifting sequences require a shallow, proximal to the NBL magma chamber or can originate from a deeper source as vertical dikes and then transition to lateral propagation.Figure 1: Buoyant hydraulic fracture encountering a neutral buoyancy line.References[1] A. Möri and B. Lecampion. Three-dimensional buoyant hydraulic fractures: constant release from a point source. J. Fluid Mech., 950, A12, 2022.[2] D. I. Garagash and L. N. Germanovich. Gravity driven hydraulic fracture with finite breadth. In Proceedings of the Society of Engineering Science 51st Annual Technical Meeting, 2014.[3] D. I. Garagash and L. N. Germanovich. Notes on propagation of 3D buoyant fluid-driven cracks. arXiv:2208.14629, 2022.[4] T. Davis, E. Rivalta, and T. Dahm. Critical fluid injection volumes for uncontrolled fracture ascent. Geophys. Res. Lett., 47, 14, 2020.[5] J. R. Lister. Buoyancy-driven fluid fracture: similarity solutions for the horizontal and vertical propagation of fluid-filled cracks. J. Fluid Mech., 217:213–239, 1990.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".