Abstract
Horizontal hydraulic opening-mode fractures are widely developed across sedimentary, magmatic, and metamorphic crustal environments. For the general case where the vertical stress corresponds to the lithostatic load, such fracturing is favored under compressive stress regimes at low differential stress, when the fluid pressures exceeding the lithostatic load (i.e., achieving super-lithostatic fluid overpressures). In many cases these fractures contain blocky mineral fills, indicating that deposition occurred within an open, fluid-filled space owing to a lack of spanning during opening. Some evidence from primary fluid inclusions within these blocky cements, along with some conceptual interpretation from all three crustal systems, demonstrate that super-lithostatic fluid overpressures could also be present during syn-kinematic blocky cementations within these fractures, which provided the potential for maintaining them open against the lithostatic load and accommodating blocky crystallization.
However, the mechanical significance of such fluid-pressure–tectonic coupling, particularly the role of super-lithostatic fluid overpressure in sustaining horizontal fractures open and blocky cementation have not yet been systematically synthesized across crustal environments. In this review, we focus on the scenarios where super-lithostatic fluid overpressure does occur, and its coupling with tectonic stresses to facilitate horizontal hydraulic opening-mode fracturing and blocky cementation in the crust. Some case studies across diverse systems demonstrate that super-lithostatic fluid overpressures—generated via gas generation during thermal cracking in sedimentary shales, volatile exsolution within intrusion roof zones in magmatic systems (e.g., porphyry-epithermal ore deposit, granite-related Sn-W deposit and pegmatite), or devolatilization reactions in metamorphic orogenic gold belts—consistently coupled with compressive regimes to drive horizontal hydraulic fracturing and sustain open spaces for blocky deposition. Taken together, this synthesis highlights that super-lithostatic fluid overpressure plays a pivotal dual role in both forming horizontal opening-mode fracturing and mechanically maintaining the open spaces required for subsequent blocky cementation, a mechanism that directly controls crustal fluid focusing and mineral accumulation, particularly for sedimentary hydrocarbons, orogenic precious metals, and magmatic critical minerals.
Paper Information：
Miao Wang, Xinxin Gao, Yelei Wang, Yong Chen, Daniel Moncada, Fang Hao, Tao Hu, Fulai Li, Yifan Song, Ziye Lu, Xin Zeng, Zhiming Zhang, Enze Wang, Matthew Steele-MacInnis. Super-lithostatic fluid overpressure–tectonic coupling in horizontal opening-mode fracturing and blocky cementation in the crust. Earth-Science Reviews, 2026, 281,105630. https://doi.org/10.1016/j.earscirev.2026.105630
