Abstract
The origin of minor leucocratic intrusions known as “plagiogranites” in oceanic complexes dominated by basaltic compositions have been debated in the literature. Here we use well preserved plagiogranites within the contrasting Santa Elena Ophiolite and the Nicoya Complex, NW Costa Rica, to investigate the origin and age of these leucocratic intrusions. Magmatic zircons of plagiogranites of the Santa Elena ophiolite and the Nicoya Complex, yield weighted mean SHRIMP 206Pb/238U ages of 125.3 ± 2.0 Ma and 90.9 ± 2.0 Ma to 88.5 ± 2.0 Ma (n = 5), respectively. These ages record the main magmatic phases of formation of these intrusions preserved in each complex. Relatively flat, unfractionated chondrite-normalized REE patterns of plagiogranites from both complexes mimic signatures of related mafic rocks, which is consistent with formation via fractional crystallization from a mafic source as opposed to partial melting of a mafic (basalt, amphibolite) protolith. In the case of the Nicoya Complex, modelling suggests that the Nicoya plagiogranites are consistent as ~ 10–15% residual liquids after fractional crystallization from its mafic parental source. Trace element systematics of the plagiogranites are consistent with an oceanic arc origin for Santa Elena and a mostly mid-ocean ridge to oceanic-plateau origin for Nicoya.
| Original language | English |
|---|---|
| Pages (from-to) | 75-87 |
| Number of pages | 13 |
| Journal | Lithos |
| Volume | 262 |
| DOIs | |
| Publication status | Published - 2016 Oct 1 |
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Keywords
- Central America
- Costa Rica
- Nicoya
- Ophiolite
- Plagiogranite
- Santa Elena
ASJC Scopus subject areas
- Geochemistry and Petrology
Cite this
Origin of plagiogranites in oceanic complexes : A case study of the Nicoya and Santa Elena terranes, Costa Rica. / Whattam, Scott A.; Gazel, Esteban; Yi, Keewook; Denyer, Percy.
In: Lithos, Vol. 262, 01.10.2016, p. 75-87.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Origin of plagiogranites in oceanic complexes
T2 - A case study of the Nicoya and Santa Elena terranes, Costa Rica
AU - Whattam, Scott A.
AU - Gazel, Esteban
AU - Yi, Keewook
AU - Denyer, Percy
PY - 2016/10/1
Y1 - 2016/10/1
N2 - The origin of minor leucocratic intrusions known as “plagiogranites” in oceanic complexes dominated by basaltic compositions have been debated in the literature. Here we use well preserved plagiogranites within the contrasting Santa Elena Ophiolite and the Nicoya Complex, NW Costa Rica, to investigate the origin and age of these leucocratic intrusions. Magmatic zircons of plagiogranites of the Santa Elena ophiolite and the Nicoya Complex, yield weighted mean SHRIMP 206Pb/238U ages of 125.3 ± 2.0 Ma and 90.9 ± 2.0 Ma to 88.5 ± 2.0 Ma (n = 5), respectively. These ages record the main magmatic phases of formation of these intrusions preserved in each complex. Relatively flat, unfractionated chondrite-normalized REE patterns of plagiogranites from both complexes mimic signatures of related mafic rocks, which is consistent with formation via fractional crystallization from a mafic source as opposed to partial melting of a mafic (basalt, amphibolite) protolith. In the case of the Nicoya Complex, modelling suggests that the Nicoya plagiogranites are consistent as ~ 10–15% residual liquids after fractional crystallization from its mafic parental source. Trace element systematics of the plagiogranites are consistent with an oceanic arc origin for Santa Elena and a mostly mid-ocean ridge to oceanic-plateau origin for Nicoya.
AB - The origin of minor leucocratic intrusions known as “plagiogranites” in oceanic complexes dominated by basaltic compositions have been debated in the literature. Here we use well preserved plagiogranites within the contrasting Santa Elena Ophiolite and the Nicoya Complex, NW Costa Rica, to investigate the origin and age of these leucocratic intrusions. Magmatic zircons of plagiogranites of the Santa Elena ophiolite and the Nicoya Complex, yield weighted mean SHRIMP 206Pb/238U ages of 125.3 ± 2.0 Ma and 90.9 ± 2.0 Ma to 88.5 ± 2.0 Ma (n = 5), respectively. These ages record the main magmatic phases of formation of these intrusions preserved in each complex. Relatively flat, unfractionated chondrite-normalized REE patterns of plagiogranites from both complexes mimic signatures of related mafic rocks, which is consistent with formation via fractional crystallization from a mafic source as opposed to partial melting of a mafic (basalt, amphibolite) protolith. In the case of the Nicoya Complex, modelling suggests that the Nicoya plagiogranites are consistent as ~ 10–15% residual liquids after fractional crystallization from its mafic parental source. Trace element systematics of the plagiogranites are consistent with an oceanic arc origin for Santa Elena and a mostly mid-ocean ridge to oceanic-plateau origin for Nicoya.
KW - Central America
KW - Costa Rica
KW - Nicoya
KW - Ophiolite
KW - Plagiogranite
KW - Santa Elena
UR - http://www.scopus.com/inward/record.url?scp=84978225190&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84978225190&partnerID=8YFLogxK
U2 - 10.1016/j.lithos.2016.06.017
DO - 10.1016/j.lithos.2016.06.017
M3 - Article
AN - SCOPUS:84978225190
VL - 262
SP - 75
EP - 87
JO - Lithos
JF - Lithos
SN - 0024-4937
ER -