Tonian evolution of an active continental margin - a model for Neoproterozoic NW India-SE Pakistan–E Oman linkage

de Wall H, Regelous A, Tomaschek F, Bestmann M, Hahn G, Sharma KK (2022)

Publication Type: Journal article

Publication year: 2022

Journal

Precambrian Research Elsevier

Book Volume: 381

Article Number: 106822

DOI: 10.1016/j.precamres.2022.106822

Abstract

Here we introduce a new model for a Tonian active continental margin in the Neoproterozoic western foreland of the Delhi Fold Belt of NW India. This study gives indication for a transition from continental crust into an active arc setting prior to emplacement of the volcano-plutonic Malani Igneous Suite. Erinpura Granites (890 to 860 Ma) are exposed in a large area west of the Delhi Fold Belt in NW India. The Erinpura Granites are S-type (εNd −10 to −3) whereas granites, granodiorites and gabbros exposed in the westernmost basement outcrops (Bhinmal, Harsani) are I-type granitoids and show positive Nd ratios (εNd + 4 to + 6). These intrusions are derived from crustal melting with a lithospheric component and affinity to a subduction setting, as can also be inferred from trace element ratios. Our study places the Bhinmal granite as youngest intrusion in this setting (U-Pb analyses of zircon 794 ± 17 Ma and titanite 793 ± 19 Ma). High temperature linear solid-state fabrics in the granites indicate intrusion and deformation during crustal extension. After uplift and exhumation bimodal dykes and granites of the Malani Igneous Suite (770–750 Ma) intruded into this older crust (pre-Malani basement). An evolutionary model for a Tonian active continent margin is established by integrating data from Nagar Parkar in East Pakistan and Neoproterozoic basement inliers in East Oman. The data indicate 130 Myr of ongoing subduction (900 to 770 Ma) along the continental margin. Magmatic activity is identified as episodic with three major pulses starting at ca. 840 Ma, ca. 825 Ma and ca. 770 Ma. High temperature melting constitutes the last Tonian magmatic pulse (Malani Igneous Suite) attributed to roll-back of the subducting slab. The implications for Neoproterozoic plate tectonic reconstructions are discussed.

Authors with CRIS profile

Helga de Wall Professur für Tektonik Anette Regelous Geozentrum Nordbayern Michael Bestmann Professur für Tektonik

Involved external institutions

Rheinische Friedrich-Wilhelms-Universität Bonn DE Germany (DE) University of Leicester GB United Kingdom (GB) Jaywanti Haksar Governement Post Graduate College, Betul IN India (IN)

How to cite

APA:

de Wall, H., Regelous, A., Tomaschek, F., Bestmann, M., Hahn, G., & Sharma, K.K. (2022). Tonian evolution of an active continental margin - a model for Neoproterozoic NW India-SE Pakistan–E Oman linkage. Precambrian Research, 381. https://dx.doi.org/10.1016/j.precamres.2022.106822

MLA:

de Wall, Helga, et al. "Tonian evolution of an active continental margin - a model for Neoproterozoic NW India-SE Pakistan–E Oman linkage." Precambrian Research 381 (2022).

BibTeX: Download