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The Association of Petroleum Geologist (APG) India successfully conducted a comprehensive field workshop on Sedimentary Facies Analysis and Basin Evaluation in the Indo-Tsangpo suture zone (ITSZ) from 10th to 18th October 2023. The workshop aimed to enhance the understanding of subduction and collision tectonics in the Himalayan and Trans Himalayanregion tectonically separated by ITSZ.
Executives from prominent organizations such as ONGC, DGH, OVL, and Vedanta actively participated in the workshop, contributing to the diversity of perspectives and expertise. This collaborative effort fostered a rich learning environment, facilitating the exchange of knowledge and insights among industry professionals.
The Magnificent field workshop was inaugurated by Shri. Vikas J Pandey, President of APG and an esteemed representative of ONGC. His inaugural address set the tone for an insightful exploration of the geological complexities present in Tethyan and Trans-Himalaya region in the Indo-Tsangpo suture zone.
The workshop was led by Professor Rajeev Upadhyay from Kumaon University, Nainital - Uttarakhand. Prof. Upadhyay’s profound expertise and engaging teaching style ensured that participants gained valuable insights into sedimentary facies analysis and basin evaluation techniques specific to the unique geological context of the Indo-Tsangpo suture zone and about the complexity and geo dynamic processes related to the plate collision and closing of the Tethys Sea.
Throughout the eight-day workshop, participants actively delved into an exploration of the region, immersing themselves in hands-on activities and field excursions. The program involved tasks such as identifying lithological variations, locating the contact points of suture zones and plate margins, and sampling the rock specimens and representative fossils in the Himalayan and Trans-Himalayan region.
The field interactive sessions were strategically designed to elevate participants' practical skills specific to geological processes. The focus extended from understanding the geological timelines spanning from Precambrian to Recent times in context of the Himalayan Orogeny. Notably, the workshop offered a comprehensive examination of collision tectonics in the Indo-Tsangpo suture zone, providing participants with a holistic perspective on the geological process shaped the region.
Day 1 of the immersive field workshop commenced with visit to Thiksey village. Thisregion is enveloped by the Ladakh batholiths, exhibiting prominent grano-diorite bands within the darker dioritic mass. The batholith's extrusion occurredin four distinct phases spanning from 58 to 50 million years ago. The field exploration extended to Hemis, where conglomerate situated in an intermontane setting, revealing intriguing Siwalik equi-fossils was observed. However, the true highlight of the day unfolded at a remarkable section along the Lato bridge where, the surface manifestation of the Indus-Tsangpo Suture Zone (ITSZ) was prominently visible. Above the thrustan amalgamation of ophiolitic melange and conglomerate from the Asian plate is present. Beneath the thrust, the stratigraphy shifted to the turbidite slope deposits originating from the Indian plate, adding layers of complexity.
The second day traverse charted a course to the northwest from Leh, encountering moraine sediments en route to Magnetic Hill. The nomenclature of Magnetic Hill stems from the subtle ferro/ferri-magnetism exhibited by iron-rich rocks originating from the plutonic protoliths. A pivotal juncture unfolded at the confluence of the Indus and Zanskar rivers, towards southward turn to Chilling village in the dip direction. The dip traverse afforded a revealing glimpse into the geological tapestry, showcasing Oligocene conglomerate supported by oriented red-green clasts from the Indus Group, indicative of continental marginal marine tidal facies. Noteworthy features included substantial recumbent folds with Cretaceous rocks forming the core and Eocene rocks flanking the limbs. Further the Eocene dolomitic limestone, forming a reef set-up rich in nummulites and thalessenoid burrows, emblematic of a shallow marine environment during the Eocene epoch was observed.
The day culminated at Lamayaru, where the landscape exhibited magnificent Quaternary glacio-lacustrine freshwater deposits, showcasing remarkable fossils such as Ostracods. These deposits were laid bare due to the breach of a glacial lake, providing a captivating window into the geological history of the region.
Day 3 commenced with an exploration of the Lamayaru Complex, an intriguing turbidite featuring low-grade slates to phyllites adorned with flattened Daonella Indica bivalves, characteristic of the mid-to-late Triassic period. The geological continuity extends to the Fotula Pass rocks, spanning from the Middle Triassic to the Upper Cretaceous.Heading southward, colossal hills emerge, formed by dolomitic shelf sediments originating from the Indian plate. In the northern direction, the landscape transforms, revealing Ophiolitic melange and Fore-arc sediments. Our traverse through the Kanji Gorge uncovered sections displaying recrystallized Rudist bivalves from the Chikkim Formation, indicative of the Tethys Sea during the Aptian-Albian period.
A significant geological encounter took place at the thrusted contact of the Indus-Tsangpo Suture Zone (ITSZ) between the Lamayaru Complex and Ophiolitic Melange. Notably, the Ophiolitic Melange displayed the presence of radiolarian chert, a novel observation in this context. The Chiktan Nalla section showcased intercalations of green and red sandstone, siltstone, and shales, forming the turbidite Nindam Formation. These deposits, spanning from the Upper Cretaceous to Paleocene, represent trench deposits featuring impressive flute casts, parallel, and convolute laminations.
The geological narrative continued with the exposure of enormous pillow basalts from the Ophiolitic Melange in this section, adding another layer of complexity to our understanding of the region's geological history.
On the Day 4 traverse was taken due Noth from Leh to Diskit Village via Khardung pass. Along this entire traverse, entire components of the ophiolitic melange with peridotites & pyroxenites at the base, Gabbro, sheeted dykes complex, basaltic pillow lavas and seafloor radiolarian chert were observed. In the Khardung region, the geological formations date back to approximately 68-60 million years ago and consist of a diverse range of volcanic rocks, including Basalt, Andesite, and Rhyolite. The presence of agglomerate with volcanic bomb clasts suggests explosive volcanic activity. Additionally, minor occurrences of pitchblende indicate a connection with an Island Arc tholeiitic volcanic system.
Moving to the Khalsar section, the rocks undergo significant deformation due to the Karakoram transfer Fault, resulting in highly sheared chlorite schist. The proximity to this fault zone is marked by increased metamorphism. However, with distance from the fault, less metamorphosed chlorite schist and its precursor, chlorite-bearing Shyok volcanics, are evident.
As one ascends a hill along the road, a distinct geological boundary known as the Shyok suture zone becomes apparent. The hanging wall is composed of greenish Shyok metavolcanics dating to 118 million years ago, while the footwall comprises Eocene to Cretaceous Saltoro Formation dolomitic limestone. This geological contact is characterized by a thrust fault trending east-west and dipping north.A second prominent thrust contact is observed, separating the Saltoro Formation from remnants of the Leh-Ladakh arc system in the back arc. This thrust dips towards the northeast, indicating the tectonic forces that have shaped the geological history of the region.
Day 5 traverse was to northward from Diskit village to Thang, the last village in India. Along this route, the geological features of the Nubra Valley became apparent, showcasing a combination of glacio-fluvio-aeolian deposits. Noteworthy elements included moraines, braided channels of the Shyok River, and the presence of distinctive sand dunes.In the Waris village in the Siachen glacial valley, observations revealed the occurrence of pillow basalt and radiolarian cherts within the ophiolitic melange. This geological setting provided insights into the complex history of the region.Continuing journey beyond the Shyok suture zone to the north, the landscape unfolded to reveal the rocks of the Karakoram Batholiths. This marked a significant geological transition, showcasing the unique characteristics of this intrusive igneous formation.
The village of Thang holds special significance as it serves as the demarcation point between India and Pakistan-occupied Kashmir (PoK), with the Shyok River valley acting as the natural boundary. This geological setting not only delineates political boundaries but also represents a fascinating intersection of diverse geological formations, adding depth to our understanding of the Earth's dynamic processes in this region
On the sixth day, we undertook an extensive and demanding expedition heading southward to reach Pangong Lake, traversing the deposits of the Shyok River. A geological section near Sati village provided a fascinating glimpse into the region's history, revealing six distinct stages of seismites within deposits shaped by glacial, fluvial, and lacustrine processes.
Before arriving at Shyok Village to the southeast, we encountered foliated Karakoram batholiths exhibiting slickensides—a noteworthy geological feature indicative of tectonic activity. Subsequently, we pressed on with our journey toward Pangong Lake.Pangong Lake, a saline water body, is shared between India (30%) and China (70%). The lake's dynamic color changes are a reflection of its mineral composition. As we directed our attention to the northeast, the landscape was graced by the imposing presence of the magnificent Karakoram Batholiths, adding a geological spectacle to our exploration.
The success of this workshop is attributed to the collaborative efforts of APG, the esteemed presence of industry leaders, and the expert guidance provided by Professor Rajiv Upadhyay. The knowledge gained during this workshop will undoubtedly contribute to advancing exploration and understanding in the field of petroleum geology within the Indo-Tsangpo suture zone and in the context of Himalayan Foreland Basins.
This workshop serves as a testament to APG’s commitment to fostering knowledge exchange and professional development within the geoscience community. The collaboration between academia, industry, and professional organizations showcased the importance of such initiatives in advancing the understanding of complex geological terrains.
In conclusion, the Sedimentary Facies Analysis and Basin Evaluation workshop in Leh, India, stands as a noteworthy event in the field of petroleum geology, marking a significant contribution to the ongoing exploration and understanding of the Indo-Tsangpo suture zone.
We express our sincere gratitude to APG India for orchestrating an unforgettable Geological Field Trip to Leh. This venture owes its success to the unwavering commitment and diligence of the entire APG India team, who dedicated themselves tirelessly to ensure the triumph of this educational expedition.
Our heartfelt thanks extend to our esteemed Patron, APG Smt. Sushma Rawat, whose visionary leadership in the field of geology inspired us to embark on this journey. We are deeply thankful for your patronage, which made this field trip possible.
Special appreciation goes to President APG Shri Vikas J. Pandey for inaugurating the Field Trip and being present during its initial days. Your belief in the significance of field-based geological education empowered us to explore the wonders of Himalayan geology. We express sincere gratitude for your invaluable guidance.
We acknowledge the dedication and enthusiasm of Vice President Shri Nandan Verma, whose exceptional commitment greatly contributed to the trip's success. Your role has been instrumental in achieving the expedition's goals.
Our regards extend to Secretary Shri J.P. Dobriyal for meticulous planning and coordination, critical to the seamless execution of the field trip. Your tireless efforts ensured a well-structured and successful expedition.
A special mention goes to Prof. Rajeev Upadhyay, Kumaun University, whose mentorship enriched our Geological Trip. With over 35 years of experience in the Himalayas, your extensive knowledge, patience, and approachability were exemplary. Thank you for being a reservoir of geological wisdom and inspiration.
In closing, our heartfelt gratitude goes to coordinators Shri Asis Mandal, Shri Vijay Singh, and Shri Bhargav Kashyap for their exceptional efforts in planning and execution.
This field trip provided a unique opportunity to explore Leh's geological wonders, expand our knowledge, and experience the rich geological heritage. The learnings gained will be invaluable in our academic and professional pursuits.
We also acknowledge the support of local authorities, communities, and all who welcomed us. Your hospitality enriched our experience.
In conclusion, we thank APG India for their vision in organizing this Geological Field Trip to Leh. The journey broadened our horizons, deepened our appreciation for Earth's geological wonders, and strengthened our commitment to geological science. With gained knowledge and memories, we eagerly anticipate continuing our exploration of Earth's geological mysteries and contributing to the field