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Using 3D gyrofluid simulations, we revisit the problem of Alfven-wave (AW)collisions as building blocks of the Alfvenic cascade and their interplay withmagnetic reconnection at magnetohydrodynamic (MHD) scales. Depending on thelarge-scale nonlinearity parameter $\chi_0$ (the ratio between AW linearpropagation time and nonlinear turnover time), different regimes are observed.For strong nonlinearities ($\chi_0\sim1$), turbulence is consistent with adynamically aligned, critically balanced cascade--fluctuations exhibit ascale-dependent alignment $\sin\theta_k\propto k_\perp^{-1/4}$, a$k_\perp^{-3/2}$ spectrum and $k_\|\propto k_\perp^{1/2}$ spectral anisotropy.At weaker nonlinearities (small $\chi_0$), a spectral break marking thetransition between a large-scale weak regime and a small-scale$k_\perp^{-11/5}$ tearing-mediated range emerges, implying that dynamicalignment occurs also for weak nonlinearities. At $\chi_0<1$ the alignmentangle $\theta_{k_\perp}$ shows a stronger scale dependence than in the$\chi_0\sim1$ regime, i.e. $\sin\theta_k\propto k_\perp^{-1/2}$ at$\chi_0\sim0.5$, and $\sin\theta_k\propto k_\perp^{-1}$ at $\chi_0\sim0.1$.Dynamic alignment in the weak regime also modifies the large-scale spectrum,scaling roughly as $k_\perp^{-3/2}$ for $\chi_0\sim0.5$ and as $k_\perp^{-1}$for $\chi_0\sim0.1$. A phenomenological theory of dynamically alignedturbulence at weak nonlinearities that can explain these spectra and thetransition to the tearing-mediated regime is provided; at small $\chi_0$, thestrong scale dependence of the alignment angle combines with the increasedlifetime of turbulent eddies to allow tearing to onset and mediate the cascadeat scales that can be larger than those predicted for a critically balancedcascade by several orders of magnitude. Such a transition to tearing-mediatedturbulence may even supplant the usual weak-to-strong transition.

Turbulent regimes in collisions of 3D Alfv\'en-wave packets