An 8–10 Ma tectonic event on the Cocos Plate offshore Costa Rica: Result of Cocos Ridge collision?

Abstract

Upper oceanic crust within the Cocos Plate offshore northwestern Costa Rica is dominated by sill intrusions of various ages, recognized regionally as smooth, high amplitude seismic reflections at the base of the sedimentary sequence and locally by dolerites and microgabbros recovered by drilling. Earlier interpretation of seafloor magnetic anomalies documented a set of spreading ridge jumps at 19.5 and 14.5 Ma, continuing to the present. In addition to these events, we present evidence for a widespread tectonic event in the period 8–10 Ma displayed in reflection seismic data recorded during the Ticoflux 1 and 2 experiments and dated by seismic correlation to ODP Site 1039. The 8–10 Ma events may have been triggered by collision of the Cocos Ridge at this time and facilitated by widespread sill intrusion associated with the Galapagos Hot Spot.

Geochemical variations in the Cocos Plate subducting beneath Central America: implications for the composition of arc volcanism and the extent of the Galápagos Hotspot influence on the Cocos oceanic crust

“…They occur about 100 km northwest of the seamount province, forming the northern part of the morphological Galápagos Hotspot Track. The age of the underlying crust and biostratigraphy of intruded sediments suggest that these gabbros are \16 Ma, possibly as young as 8-10 Ma (Barckhausen et al 2001;Muza 2000;Silver et al 2004) (see Kimura et al 1997 for more background information about these samples). Samples from Fisher Ridge (*17 Ma) are fresh basaltic glasses (44/96Co and 47/96Co) and a manganese crust (66/96Co) obtained on RV Sonne 81-6 cruise.…”

“…Here we provide the first look at the variations in the isotopic composition of the uppermost crust at Site 1256. Data from gabbroic sills from ODP Sites 1039 and 1040 will be evaluated to determine the origin of these sills, specifically if they could be derived from the Galápagos Hotspot (Silver et al 2004). We also report new data from the Fisher Ridge at the northwestern edge of the Galápagos Hotspot Track, representing near-trench uplifted ocean crust, and the Galápagos Hotspot Track to constrain the input into the Central American subduction zone better.…”

“…1). The oceanic crust at ODP Site 1256 is *15 million-year-old, gabbros from Sites 1039 and 1040 are \16 Ma, the ocean floor at the Fisher Ridge is *19 Ma, and samples from the Galápagos Hotspot Track are *13-15 Ma (Silver et al 2004;Werner et al 1999;Wilson et al 2003).…”

From incipient island arc to doubly‐vergent orogen: A review of geodynamic models and sedimentary basin‐fills of southern Central America

“…It is well known that the seafloor roughness (e.g. E. Silver, et al, ) has a strong influence on vertical movements of the upper plate (Sak et al, ). Crust with a rough morphology, entering the subduction zone initially caused uplift of the upper plate, followed by increased subsidence due to enhanced subduction erosion (Sak et al, ; Zeumann & Hampel, ).…”

Igneous Rock Associations 13. Focusing on the Central American Subduction Zone

“…and the CASZ that started ca. 15-10 Ma (Denyer and Arias 1991;Silver et al 2004;MacMillan et al 2004;) clogged the subduction zone and triggered slab detachment below southern Costa Rica and Panama. The detached slab segments were then replaced by hot asthenosphere, which is consistent with the elevated mantle potential temperatures (1400-1450 °C) in the mantle wedge below southern Central America (Gazel et al 2011).…”