Abstract
Amphibole-dominated dehydration melting of gabbro is the primary process responsible for the genesis of adakites, low-K tonalites, modern trondhjemites, and plagiogranites as well as Archean tonalite-trondhjemite-granodiorite suites that represent the earliest examples of continental crust. Previous literature has mostly focused on the role of Al-rich amphibole during anatexis of a mafic source and many of these studies have investigated this process through experimental melting runs. However, due to experimental boundary conditions, little is known about partial melting of amphibole-bearing mafic rock at temperatures < 800°C for upper crustal conditions (pressure < 500 MPa). Classic and forward thermobarometric modelling suggests that in situ trondhjemite leucosomes, hosted by Cheshmeh-Ghasaban mafic metatexites (Alvand Plutonic Complex, Hamedan, NW Iran), represent a rare natural case study of a low-temperature incipient amphibole-dominated anatectic event of a mafic source with a primary assemblage (Pl+Hbl+Cpx+Bt+Opx) typical of a hornblende-bearing gabbroic rock.
Highlights
We present the field occurrences, petrography, and mineralogy characterizing the studied Hblgabbro protolith and the in situ trondhjemite leucosomes
The hornblende-bearing gabbros outcropping at CheshmehGhasaban locality are a key area to investigate mafic migmatites and amphibole-controlled anatexis developed in the upper crust
(ii) The equilibrium batch melting (EBM) modelling indicates that the trondhjemite leucosomes are generated by a very low (< 2%) degree of batch melting of the hornblende-bearing gabbroic protolith
Summary
Crustal anatexis characterized by melt segregation and extraction is considered one of the key processes for the genesis of large volumes of felsic magmas and for continental crustal growth and differentiation (e.g., Clemens 1990; Vielzeuf and Vidal 1990; Johannes and Holtz 1996; Clemens and Watkins 2001; Kriegsman 2001; Ratajeski et al 2005; Sisson et al 2005; Gao et al 2016; Rossetti et al 2020; Saki et al 2021). A review of the existing chemistry data of experimental melts from mafic to metapelitic protoliths was recently published by Gao et al (2016) Among all these studies, there was great emphasis on experimental and natural evidence for amphibole-dominated dehydration melting of mafic magmatic and metamorphic sources such as basalts, andesites, gabbros, greenstones, amphibolites, and eclogites
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
