décollement

Décollement is a term used in several scientific and clinical fields to describe the separation or detachment of one material, layer, or tissue from another along a distinct plane. The concept implies loss of cohesion and often creates a mechanical decoupling that can alter function, motion, or integrity of the system involved.

In geology, a décollement (ou surface de décollement) is a mid-crustal plane along which overlying rock units detach and slide relative to deeper units during compressional tectonics. It commonly forms in clay-rich intervals and acts as a decoupling horizon that localizes thrusting, nappe formation and duplex structures. Detachment levels influence deformation style and surface topography.

In obstetrics, the expression décollement placentaire, or placental abruption, designates premature detachment of the placenta from the uterine wall before or during labor. It can cause vaginal bleeding, abdominal pain and fetal distress. Risk factors include hypertension, trauma, smoking, and advanced maternal age. Management is obstetric emergency, prioritizing maternal stabilization and fetal status; the approach depends on gestational age and severity.

Décollement de la rétine, or retinal detachment, occurs when the retina separates from its underlying tissue. It can result from retinal tears or degeneration and presents with sudden vision changes such as flashes, floaters or a shadow over the field of vision. Treatment includes laser therapy or surgical procedures (cryotherapy, scleral buckling, vitrectomy) to reattach the retina.

In materials science and engineering, delamination or décollement describes the separation between layers in laminated composites or coatings. Causes include moisture ingress, thermal cycling, residual stresses, or impact. Delamination degrades stiffness and strength and is detected by non-destructive testing; remediation may involve improved bonding, barrier layers, or revised processing to restore integrity.