This study documented the field relationship and integrated provenance of a clastic sequence exposed at the Mesozoic–Cenozoic boundary located in Changla Gali section, Lesser Himalaya, Pakistan, to provide an insight into Cretaceous tectonics of the northern Indian margin. This boundary sequence is represented by the Early Palaeocene Hangu Formation, which consists of shales in the lower part and sandstone in the upper part. The contact relationship of the Early Palaeocene Hangu Formation with the underlying Late Cretaceous Kawagarh Formation is marked by an angular unconformity. The detrital zircons extracted from the shale and sandstone samples shows a major age cluster, which varies between ~700 and ~1,100 Ma (45%), ~1,600 and ~1,900 Ma (15%), and ~480 and ~590 Ma. Additionally, two minor age clusters of the detrital zircons are identified, that is, ~2,300–2,500 Ma and ~600–700 Ma. The younger detrital zircon grains have ages of 298 ± 4 Ma, 297 ± 4 Ma and 116 ± 3 Ma. This age pattern reflect the major source area as the Indian Plate. The two younger Permian zircon grains may be derived from the Panjal mafic volcanic rocks exposed in the vicinity of the study area. However, a single Cretaceous grain may be attributed to ophiolites, as well as Tethyan Himalayan (TH) volcanic rocks. Similarly, the sandstone petrographic results show that the sandstones are quartz‐rich, which show derivation from the craton interior provenance, which is likely the Indian Plate. However, the trace element data suggest a mixed source consisting of felsic and mafic rocks. The contribution of the mafic source is likely associated with the Panjal mafic rocks exposed along the northern Indian margin. The field relationship shows that the underlying Mesozoic sequence is folded prior to the deposition of the Hangu Formation. This folding suggests that the northern Indian margin experienced a regional compression during the Late Cretaceous time, which folded the Mesozoic sequence before the resumption of sedimentation during the Palaeocene. Furthermore, the detrital zircon provenance suggests that the sediments were mainly derived from the Indian Plate. Combining the results, it can be concluded that the compressional event is likely associated with the Late Cretaceous ophiolite obduction onto the leading edge of the Indian Plate. However, the absence of the major ophiolitic age component in the detrital record may suggest that the ophiolites were emplaced over the northern Indian margin but remained submerged during Early Palaeocene time.
This study reports on the detrital zircon provenance of the sandstones of Early Paleocene Ranikot Formation exposed in the Fort Munro section, Sulaiman fold-thrust belt, Pakistan. This marks the Cretaceous-Tertiary boundary sequence. The detrital zircon U-Pb ages reported are mainly clustered around ~460–1100 Ma, ~1600–1900 Ma and ~2300–2600 Ma. The age cluster ~460–1100 Ma is mainly matched well with the Tethyan Himalaya. However, the age clusters ~1600–1900 Ma and ~2300–2600 Ma matched fairly with the lesser Himalayas and Higher Himalayas. In addition, the sandstone petrography suggests the craton interior provenance. The two younger Cretaceous zircon ages may be derived from the Tethyan Himalaya volcanic rocks as supported by a high (>0.3) Th/U ratio. Furthermore, the absence of the ophiolitic component ~115–178 Ma suggests that the western ophiolite may be emplaced at the same time as Ranikot Formation deposited or later. Moreover, the absence of the Eurasian (zircon with ages <100 Ma) in the Ranikot Formation excludes the possibility of the early collision along the western margin, as reported in earlier studies.
Geodiversitas est indexé dans / Geodiversitas is indexed in:-Science Citation Index Expanded (SciSearch ® ) -ISI Alerting Services ® -Current Contents ® / Physical, Chemical, and Earth Sciences® -Scopus ® Geodiversitas est distribué en version électronique par / Geodiversitas is distributed electronically by: -BioOne ® (http://www.bioone.org) Les articles ainsi que les nouveautés nomenclaturales publiés dans Geodiversitas sont référencés par / Articles and nomenclatural novelties published in Geodiversitas are referenced by: -ZooBank ® (http://zoobank.org) GEODIVERSITAS • 2021 • 43 (18) © Publications scientifiques du Muséum national d'Histoire naturelle, Paris.
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