Late Miocene to recent plate tectonic history of the southern Central America convergent margin

Abstract

New plate reconstructions constrain the tectonic evolution of the subducting Cocos and Nazca plates across the southern Central American subduction zone from late Miocene to recent. Because of the strong relationships between lower and upper (Caribbean) plate dynamics along this margin, these constraints have wide‐ranging implications for the timing and growth of upper plate deformation and volcanism in southern Central America. The reconstructions outline three important events in the Neogene history of this margin: (1) the coeval development of the Panama Triple Junction with the initiation of oblique subduction of the Nazca plate at ∼8.5 Ma; (2) the initiation of seamount and rough crust subduction beginning at ∼3–4 Ma; and (3) Cocos Ridge subduction from ∼2 to 3 Ma. A comparison of these events with independent geologic, geomorphic, volcanic, and stratigraphic data sets reveals that the timing, rates, and origin of subducting crust directly impacted the Neogene growth of upper plate deformation and volcanism in southern Central America. These analyses constrain the timing, geometry, and causes of a number of significant tectonic and volcanic processes, including rapid Plio‐Quaternary arc‐fore arc contraction due to Cocos Ridge subduction, the detachment of the Panama microplate at ∼1–3 Ma, and the late Miocene cessation of mantle‐wedge‐derived volcanism across ∼300 km of the subduction zone.

Normal faulting and mass movement during ridge subduction inferred from porosity transition and zeolitization in the Costa Rica subduction zone

“…The time range of the sediment removal (2.20-0.25 Ma) inferred from nannofossil age of the sediments between Units 1 and 2 are consistent with the timing of the arrival of the Cocos Ridge offshore the Osa Peninsula, i.e., $3-1 Ma, as reported from on-land chronological studies and recent modern plate reconstructions [e.g., Morell, 2015]. The time range of the sediment removal (2.20-0.25 Ma) inferred from nannofossil age of the sediments between Units 1 and 2 are consistent with the timing of the arrival of the Cocos Ridge offshore the Osa Peninsula, i.e., $3-1 Ma, as reported from on-land chronological studies and recent modern plate reconstructions [e.g., Morell, 2015].…”

“…Uplift, sedimentation, and subsidence must all have occurred quickly since the age gap across the MSR is < $0.87 Ma. This uplift is roughly coincident with the onset of Cocos Ridge subduction, which is reported to have begun 3-2 Ma [Morell, 2015] to 1 Ma [Lonsdale and Klitgord, 1978;Gardner et al, 1992] based on plate reconstructions, chronostratigraphic records, and geophysical surveys. This uplift is roughly coincident with the onset of Cocos Ridge subduction, which is reported to have begun 3-2 Ma [Morell, 2015] to 1 Ma [Lonsdale and Klitgord, 1978;Gardner et al, 1992] based on plate reconstructions, chronostratigraphic records, and geophysical surveys.…”

Plio‐Quaternary Outer Forearc Deformation and Mass Balance of the Southern Costa Rica Convergent Margin

“…Finally, plate reconstruction models independently indicate that the CRISP outer forearc region has experienced the subduction of high‐relief bathymetric features such as fracture zones, seamounts and plateaux during the same time periods that the prominent unconformities (Figure ) were forming within the CRISP study area. The first major early Pleistocene unconformity (U1) coincides with a time when reconstructions suggest that the CRISP study area should have been experiencing the effects of the oblique passage of the km‐scale relief associated with the Panama Fracture Zone (Morell, ). The additional two uplift‐subsidence cycles recorded within the slope sequence (U2 and U3 at ∼1.9 and ∼1.3 Ma, respectively) coincide with the time when the CRISP study area was experiencing the subduction of Cocos plate crust with a high number of seamounts and plateaux (seamount domain; Edwards et al, ; Morell, ).…”

“…The presence of clastic sediments, thrust faulting, and imbricate stacking, as seen in the CRISP 3D volume (Bangs et al, ; Edwards et al, ), are observations consistent with a frontal accretionary model, common in many global margin wedges (e.g., Lester et al, ). At the time of accumulation of the sediments within the margin wedge (>2.2 Ma; Vannucchi et al, ), the region of the CRISP transect was experiencing the effects of relatively slow and oblique Nazca subduction (Morell, ). This tectonic setting was likely more favorable to frontal accretion (Bangs et al, ), given analogous conditions along the western Panamanian margin, where seismic reflection profiles show an accretionary wedge is actively developing immediately to the east of the Panama Fracture Zone inboard of Nazca plate subduction (MacKay & Moore, ; Moore & Sender, ; Figure ).…”

“…Late Miocene extinction of calc‐alkaline volcanism within this range had been associated with uplift of the Talamanca due to Cocos Ridge subduction (Abratis & Wörner, ; de Boer et al, ). However, similar‐aged extinction of adjacent arc segments in Panama (Wegner et al, ) suggest that late Miocene shut‐off of calc‐alkaline active volcanism in the Talamanca was not linked to Cocos Ridge subduction and was rather related to a late Miocene plate tectonic reconfiguration (Morell, ; Morell et al, ; Rooney et al, ). The increase in range width, high elevations, and deeply incised river reaches draining the Talamanca suggest ongoing and recent rock uplift within the past few million years (Morell et al, ).…”