A modern pulse of ultrafast exhumation and diachronous crustal melting in the Nanga Parbat Massif

Guevara, Victor; Smye, Andrew J.; Caddick, Mark J.; Searle, Michael P.; Olsen, Telemak; Whalen, Lisa M.; Kylander‐Clark, Andrew; Jercinovic, Michael J.; Waters, D. J.

doi:10.1126/sciadv.abm2689

Cited by 13 publications

(9 citation statements)

References 87 publications

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“…The Nanga Parbat ‐ Haramosh syntaxial massif (NPHM) forms the core of the western Himalayan syntaxis, defined by a major change in the orogen strike (Butler, 2019). The syntaxial massif itself is characterized by Plio‐Pleistocene mineral crystallization and cooling ages, and sustained rapid (c. 10 mm/a) exhumation rates since the late Miocene, including small‐volume partial melting (Crowley et al., 2009; Guevara et al., 2022; Zeitler et al., 1993).…”

Section: Discussionmentioning

confidence: 99%

Predictive Models for Detrital Titanite Provenance With Application to the Nanga Parbat—Haramosh Syntaxial Massif, Western Himalaya

O’Sullivan,

Scibiorski,

Mark

2024

JGR Earth Surface

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Titanite is a versatile recorder of crystallization age, temperature, and host lithology, via the U–Pb system, the Zr‐in‐Ttn thermometer, and elemental composition, respectively. The paragenesis of titanite renders it especially useful for tracing detritus derived from lithologies that are infertile for the commonly used detrital zircon U‐Pb chronometer, such as sub‐anatectic metamorphism of calc‐silicates. Despite these advantages, detrital titanite analysis is underemployed, in part because the U–Pb system in titanite is often complicated by the incorporation of both inherited radiogenic Pb from precursor minerals during metamorphic reactions, and also bulk crustal common‐Pb. Recent systematic analyses of large titanite compositional data sets from diverse source rocks have revealed that the elemental composition of titanite is provenance‐specific. Here, we apply a workflow that incorporates a machine‐learning classifier to a large and representative compositional database for titanite, encompassing >11,000 analyses, with c. 6,700 points passed to our model. Only medians of the subcompositions for 205 rocks are used for our model. We reliably discriminate (>90%) between metamorphic and igneous titanite. Application of this classifier to a detrital case study from the Nanga Parbat‐Haramosh syntaxial massif of the western Himalaya reveals that titanite of different compositions formed during different orogenic events. Furthermore, titanite with significant common Pb solely derives from medium/low grade metasedimentary rocks. The method described here offers a pathway to increase the specificity of the provenance information derived from titanite; however, the published corpus of titanite data will have to be much larger before multi‐class source‐rock discrimination can be achieved reliably.

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Section: Discussionmentioning

confidence: 99%

Predictive Models for Detrital Titanite Provenance With Application to the Nanga Parbat—Haramosh Syntaxial Massif, Western Himalaya

O’Sullivan,

Scibiorski,

Mark

2024

JGR Earth Surface

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“…(2020) shows that the exhumation rates increased significantly from 4 km/Myr at 8 Ma to 9 km/Myr at 2 Ma. Previous models attributed such increases of exhumation rate to strengthening of the driving forces either from tectonic or surface processes (Guevara et al., 2022; King et al., 2016; Yang et al., 2021). Similar to the tectonic aneurysm model (Koons et al., 2013; Zeitler et al., 2001, 2014), our erosion‐driven model confirms the coupling between surface erosion and rapid uplift of the EHS.…”

Section: Implications For the Eastern Himalayan Syntaxis Evolutionmentioning

confidence: 98%

“…Modified from Guevara et al. (2022). Dashed box shows the area of the Eastern Himalayan Syntaxis (EHS).…”

Section: Introductionmentioning

confidence: 99%

Erosion‐Driven Isostatic Flow and Crustal Diapirism: Analytical and Numerical Models With Implications for the Evolution of the Eastern Himalayan Syntaxis, Southern Tibet

Yang,

Cao,

Yuan

et al. 2023

Tectonics

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The Eastern Himalayan Syntaxis (EHS) is one of the fastest exhuming regions on Earth since ∼10 Ma, and the mechanism of its fast exhumation is under debate. Different from many other studies based on tectonics‐driven models, we performed analytical analysis and numerical simulations to investigate an erosion‐driven system. Our results show that fast and focused surface erosion alone is able to exhume the lower crust on the timescale of ∼10 Myr. This process leads to the formation of a domal structure, an elevated geothermal gradient, rapid cooling of crustal rocks, and decompression melting in the lower crust. In the upper‐mid crust, the uplift of crustal rocks is caused by isostatic flow driven by pressure gradient, whose rate is limited by the driving erosional forcing. In the mid‐lower crust where decompression melting occurs, rocks entrained in a buoyant diapir experience fast uplift rate exceeding the erosional forcing. Our erosion‐driven model demonstrates an intricate coupling between surface erosion and crustal processes. Positive feedback between surface erosion and rock uplift is possible under certain conditions and crustal diapirism plays a key role in the feedback. Our study shows that both isostatic and diapiric flows play important roles in the uplift and exhumation of crustal rocks in the EHS. We highlight that erosion‐driven crustal diapirism can be one of the missing pieces explaining the evolution of the Eastern Himalayan Syntaxis.

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“…This could be a main driving force accelerating eastward crustal ow 46 . The accelerated crustal ow at the Eastern Himalayan Syntaxis (EHS) drives the localized deformation and uplift [47][48][49] , leading to the active coupling between crustal rock advection and river erosion in the EHS 50 since ~ 7 Ma (Fig. 4b).…”

Section: Mechanisms For Impeding River Incision In the Late Miocenementioning

confidence: 99%

Do fault systems impede fluvial incision in active orogens?

Cai

Jiao

et al. 2022

Preprint

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It is widely accepted that tectonism generally enhances the incision of river drainage systems. However, the question as to why on a global-scale, rivers have not incised further or more deeply into orogenic plateaus to destroy terranes over long-timescales remains ambiguous. Here we hypothesize the diverse nature of regional tectonics could have impeded river erosion to maintain plateau topography, taking Yarlung River in southern Tibetan Plateau as a case. We constrain the incision history and effect of a N-S trending tectonic rift on the evolution of fluvial incision by the low-temperature thermochronology. Results show a fast cooling since ~ 7 Ma focused near the rift structures, but markedly reduced cooling in upstream and downstream regions. This indicates that the steep flank fault of the rift controlled local rapid exhumation as a knickpoint since that time. This coincides with an episode of rapid exhumation of Eastern Himalaya Syntaxis downstream. We propose that these two co-phased tectonic systems with the accelerated late Miocene extension of southern Tibet prevented upstream migration of river knickpoints, and impeded fluvial incision. Our study highlights that the activity of fault systems may hinder regional erosion, thereby facilitating the preservation of topography and high plateau in active orogenic belts.

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A modern pulse of ultrafast exhumation and diachronous crustal melting in the Nanga Parbat Massif

Cited by 13 publications

References 87 publications

Predictive Models for Detrital Titanite Provenance With Application to the Nanga Parbat—Haramosh Syntaxial Massif, Western Himalaya

Predictive Models for Detrital Titanite Provenance With Application to the Nanga Parbat—Haramosh Syntaxial Massif, Western Himalaya

Erosion‐Driven Isostatic Flow and Crustal Diapirism: Analytical and Numerical Models With Implications for the Evolution of the Eastern Himalayan Syntaxis, Southern Tibet

Do fault systems impede fluvial incision in active orogens?

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