Mid-Tertiary (25-21Ma) lamprophyres in NW Mexico derived from subduction-modified subcontinental lithospheric mantle in an extensional backarc environment following steepening of the Benioff zone

Alberto Orozco-Garza, Jaroslav Dostal*, J. Duncan Keppie, Francisco A. Paz-Moreno

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

The mid-Tertiary lamprophyre dike swarm (~8km×2.5km in size) from Hermosillo (Sonora, NW Mexico) has calc-alkaline characteristics and includes NNW-striking, amphibole-phyric spessartite (~85% of the swarm) and NNE-striking, phlogopite-phyric kersantite. The 40Ar/39Ar geochronology of amphibole and phlogopite gives overlapping plateau ages ranging from 25 to 21Ma. Although all the lamprophyres are enriched in incompatible elements and display negative Nb-Ta and Ti anomalies on the primitive mantle-normalized plots, kersantite has higher K/Na, La/Yb, P, Ti and incompatible trace elements (e.g., Zr) compared to spessartite. The lamprophyres have radiogenic Sr and Nd isotopic signatures (87Sr/86Sr ~0.7057-0.7065 and εNd ~-1 to -2.3) suggesting derivation from the subcontinental lithospheric mantle that was previously modified by subduction-related fluids. This mantle is similar to that beneath the southern Grenvillian orogen, which has younger TDM ages than the 1.6-1.7Ga TDM ages of the Caborca block. The lamprophyric magmas were generated at various mantle depths at the southwestern edge of North America. Intrusion of the lamprophyres was synchronous with extension that produced normal faults and core complexes with WSW-vergence. Extension occurred immediately following steepening of the Benioff zone, during which the magmatic arc migrated from east to west of Hermosillo, and the lamprophyres were intruded just behind the contemporaneous arc.

Original languageEnglish
Pages (from-to)59-71
Number of pages13
JournalTectonophysics
Volume590
DOIs
StatePublished - 1 Apr 2013

Bibliographical note

Funding Information:
The project was supported by NSERC Canada and Conacyt of Mexico . We would like to thank Laurent Jolivet, Stephane Scaillet and anonymous reviewer for careful reviews that helped us improve the manuscript and to Randy Corney for technical assistance.

Keywords

  • Backarc
  • Grenville Province
  • Lamprophyre
  • NW Mexico
  • Rifting
  • Subcontinental lithospheric mantle

Fingerprint

Dive into the research topics of 'Mid-Tertiary (25-21Ma) lamprophyres in NW Mexico derived from subduction-modified subcontinental lithospheric mantle in an extensional backarc environment following steepening of the Benioff zone'. Together they form a unique fingerprint.

Cite this