28 Jun 2023
 | 28 Jun 2023

An expanded workflow for detrital rutile provenance studies: An application from the Neotethys Orogen in Anatolia

Megan A. Mueller, Alexis Licht, Andreas Möller, Cailey B. Condit, Julie C. Fosdick, Faruk Ocakoğlu, and Clay Campbell

Abstract. Sedimentary provenance is a powerful tool for reconstructing convergent margin evolution. Yet single mineral approaches, like detrital zircon, have struggled to track sediment input from mafic and metamorphic sources. Sediment input from these lithologies is especially critical for reconstructing orogenic settings dominated by terrane accretion, ophiolite obduction, and forearc inversion. Rutile can form in metamorphic and igneous rocks and hydrothermal veins, and its U-Pb age and geochemistry often records cooling from the most recent medium to high grade metamorphic event. Thus, detrital rutile complements detrital zircon datasets by offering a path forward in sedimentary provenance reconstructions when metamorphic terranes are potential source regions. However, U-Pb geochronology in rutile can be difficult due to low uranium concentrations and high discordance. Here, we present detrital rutile U-Pb geochronology and trace element geochemistry results from the Late Cretaceous to Eocene Central Sakarya and Sarıcakaya Basins in Anatolia to reconstruct provenance during Neotethys orogenesis. The resulting detrital rutile U-Pb analyses are highly discordant due to the incorporation of non-radiogenic initial Pb. We present a new workflow that accounts for low-U rutile and is based on common Pb corrections and discordance filters. The resulting age spectra are similar for grains up to 40 % concordant (60 % discordant) and across the common Pb correction methods, thus providing a path forward to confidently interpret provenance from discordant rutile grains. Together, the detrital rutile trace element geochemistry and Zr-in-rutile thermometry indicate sediment was sourced from mixed metamafic and metapelitic units with low-grade metamorphic temperatures. Low-U concentration rutile are numerous and more discordant and were predominantly sourced from Late Triassic-Early Jurassic greenschist and blueschist facies rocks with both mafic and pelitic lithologies. This corresponds to sediment derived from the Karakaya Complex, a Paleozoic subduction-accretion complex or oceanic plateau that was accreted and metamorphosed in the Triassic-Jurassic, exhumed to the surface in the Jurassic, and then deformed during Neotethys suturing in the Late Cretaceous to Paleogene. Late Triassic-Early Jurassic ages are nearly absent from the detrital zircon record, emphasizing that a multi-mineral approach, especially inclusive of low-U rutile, provides a more holistic provenance reconstruction. These detrital rutile results serve as an additional layer of data often unexplored across convergent margins globally, and thus provide an exciting path forward in characterizing diverse provenance of orogenic settings.

Megan A. Mueller et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1293', David M. Chew, 18 Sep 2023
    • RC3: 'Reply on RC1', David M. Chew, 26 Sep 2023
  • RC2: 'Comment on egusphere-2023-1293', Laura Bracciali, 25 Sep 2023
  • RC4: 'Comment on egusphere-2023-1293', Inês Pereira, 30 Sep 2023

Megan A. Mueller et al.

Megan A. Mueller et al.


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Short summary
Sedimentary provenance utilizes the composition of sedimentary rocks to investigate the sources of sediment and the geologic processes controlling it. Common techniques struggle to track mafic igneous and metamorphic rock sources, yet rutile forms in these rock types. We use rutile from ancient sedimentary rocks in Türkiye to present a new workflow for integrating rutile U-Pb ages and chemical composition into an accurate sedimentary provenance reconstruction.