Pseudotachylitic breccia from the Dhala impact structure, north-central India: Texture, mineralogy and geochemical characterization

Pati, Jayanta Kumar; Reimold, W. U.; Greshake, A.; Schmitt, Rüdiger; Koeberl, Christian; Pati, P.; Prakash, K.

doi:10.1016/j.tecto.2015.01.021

Cited by 22 publications

(28 citation statements)

References 26 publications

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“…b) Enlarged geological map of the Dhala area (modified after Pati et al. ) showing the sample locations and exposures of various rock types.…”

Section: Introductionmentioning

confidence: 99%

“…The local stratigraphy was reviewed in some detail by Pati et al. (). The central parts of the Dhala structure are partially covered by Sumen Sandstone (Kaimur Group, Vindhyan Supergroup) with a lateritized conglomerate at the top.…”

Section: Introductionmentioning

confidence: 99%

“…The suevite occurs in drill core MCB‐10 between 263 and 264.8 m core depth (Pati ; Pati et al. ). The suevite, in turn, overlies an impact melt rock body.…”

Section: Introductionmentioning

confidence: 99%

“…Along the inner margin of this monomict lithic breccia unit, seven patchy outcrops (90 m 2 to 0.03 km 2 ) of impact melt breccia occur over a distance of about 6 km in a semicircular pattern between the villages of Maniar and Pagra (Pati et al. , ). The crater floor, that is, the basement below the impact melt breccia, is composed of massive to fractured, coarse‐grained, pink, porphyritic granite, and other textural variants of granitoids and gneisses (including tonalite‐trondhjemite‐granodiorite–TTG–gneisses) that also include xenoliths of older metasupracrustals.…”

Section: Introductionmentioning

confidence: 99%

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Geochemical evidence of an extraterrestrial component in impact melt breccia from the Paleoproterozoic Dhala impact structure, India

Pati

Qu²,

Koeberl

et al. 2017

Meteorit & Planetary Scien

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The Paleoproterozoic Dhala structure with an estimated diameter of ~11 km is a confirmed complex impact structure located in the central Indian state of Madhya Pradesh in predominantly granitic basement (2.65 Ga), in the northwestern part of the Archean Bundelkhand craton. The target lithology is granitic in composition but includes a variety of meta‐supracrustal rock types. The impactites and target rocks are overlain by ~1.7 Ga sediments of the Dhala Group and the Vindhyan Supergroup. The area was cored in more than 70 locations and the subsurface lithology shows pseudotachylitic breccia, impact melt breccia, suevite, lithic breccias, and postimpact sediments. Despite extensive erosion, the Dhala structure is well preserved and displays nearly all the diagnostic microscopic shock metamorphic features. This study is aimed at identifying the presence of an impactor component in impact melt rock by analyzing the siderophile element concentrations and rhenium‐osmium isotopic compositions of four samples of impactites (three melt breccias and one lithic breccia) and two samples of target rock (a biotite granite and a mafic intrusive rock). The impact melt breccias are of granitic composition. In some samples, the siderophile elements and HREE enrichment observed are comparable to the target rock abundances. The Cr versus Ir concentrations indicate the probable admixture of approximately 0.3 wt.% of an extraterrestrial component to the impact melt breccia. The Re and Os abundances and the 187Os/188Os ratio of 0.133 of one melt breccia specimen confirm the presence of an extraterrestrial component, although the impactor type characterization still remains inconclusive.

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“…b) Enlarged geological map of the Dhala area (modified after Pati et al. ) showing the sample locations and exposures of various rock types.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…The suevite occurs in drill core MCB‐10 between 263 and 264.8 m core depth (Pati ; Pati et al. ). The suevite, in turn, overlies an impact melt rock body.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Geochemical evidence of an extraterrestrial component in impact melt breccia from the Paleoproterozoic Dhala impact structure, India

Pati

Qu²,

Koeberl

et al. 2017

Meteorit & Planetary Scien

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“…Machado et al 2009;Preuss 2012), Charlevoix, Carswell (e.g. Grieve 1996, and references therein), and Dhala (Pati et al 2013) impact structures. Only very small occurrences of such melt breccia have ever been observed in other impact structures.…”

Section: Introductionmentioning

confidence: 99%

Impact-generated pseudotachylitic breccia in drill core BH-5 Hättberg, Siljan impact structure, Sweden

Reimold

Fischer

Müller

et al. 2015

GFF

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Pseudotachylitic breccia (PTB) in the form of cm-wide melt breccia veinlets locally occurs on the exposed central uplift of the 380 Ma Siljan impact structure. The host rock to the PTBs is the so-called Järna granite of quartz monzonitic to syenodioritic composition. The nearly 603 m long BH-5 drill core from Hättberg, near the centre of the Siljan central uplift, contains numerous veins and pods of PTB. In particular, two major zones of 60 m combined width contain extensive PTB network breccias (30% actual melt breccia component), with individual melt breccia occurrences up to .1 m in length. Core logging and petrographic and geochemical analysis of the core have been performed, and the data are interpreted to suggest the following. (1) The impact event caused low to moderate (at essentially ,20 GPa) shock deformation in the host rock and in clasts of this lithology within the PTB. (2) Macroscopic deformation of the basement mainly comprises fracturing, with only localised cataclasis.(3) No evidence for shock melting (i.e. compression/decompression melting early in the cratering process) could be observed. (4) Optical and scanning electron microscopy showed that dark PTB contains a definite melt component. (5) Shearing has significantly affected this part of the central uplift, but its effects are limited to very short displacements and likely did not result in extensive melting. (6) A frictional heating component upon melt generation can, however, not be excluded, as many PTB samples contain clasts of a mafic (gabbroic) component, although only in one place along the entire core, a 1.2 cm-wide section through such material in direct contact to host rock was observed. Consequently, we suggest that, upon uplift in the central part of the impact structure, considerable melt volumes were generated locally, especially in areas that had been affected by extensive cataclasis and where grain size comminution favoured melt formation. Rapid decompression related to central uplift formation is the preferred process for the generation of the PTB melt breccias.

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Characteristic landforms and geomorphic features associated with impact structures: Observations at the Dhala structure, north‐central India

Singh

Pati

Sinha

et al. 2021

Earth Surf Processes Landf

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Geomorphological study of some of the just more than 200 known terrestrial impact structures has demonstrated that despite extensive degradation, important geomorphological keys, such as drainage pattern, topographic signatures, erosional landforms, and depositional features, can still be assessed. They can provide possible indicators to assist in the recognition of further impact structures, especially on Precambrian shields and cratonic landmasses. This study documents the surface features and landforms of the Paleoproterozoic, about 11 km diameter Dhala impact structure in India. The Dhala structure has an estimated age that is constrained stratigraphically between 1.7 and 2.5 Ga. This structure is deeply eroded, and barely has a morphological resemblance to other known terrestrial or extraterrestrial impact structures.We have analyzed the operative surface-forming processes for the Dhala area.We demand to continue the in-depth study of all terrestrial impact structures, especially the pre-Paleozoic ones, so that geomorphological criteria can be rigorously constrained and applied in conjunction with a priori remote sensing and field data to support the identification of new structures prior to their ultimate confirmation using diagnostic evidence of shock metamorphism.

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Pseudotachylitic breccia from the Dhala impact structure, north-central India: Texture, mineralogy and geochemical characterization

Cited by 22 publications

References 26 publications

Geochemical evidence of an extraterrestrial component in impact melt breccia from the Paleoproterozoic Dhala impact structure, India

Geochemical evidence of an extraterrestrial component in impact melt breccia from the Paleoproterozoic Dhala impact structure, India

Impact-generated pseudotachylitic breccia in drill core BH-5 Hättberg, Siljan impact structure, Sweden

Characteristic landforms and geomorphic features associated with impact structures: Observations at the Dhala structure, north‐central India

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