Fig 1.
Geological and geographical setting of the study area.
(a) Geographical position of Ramnagar within Jammu & Kashmir, India. (b) Detailed geological map showing major lithological units and fossil-bearing localities of the Ramnagar area. Note: The base map was generated in QGIS software using Precision3D Digital Terrain Model (DTM) high-resolution imagery (Vantor/Maxar Technologies, Copyright 2026). Geological boundaries are redrawn and modified after Basu (2004).
Table 1.
Association of numbered sandstones from this study (S1 = oldest) with fossil localities, paleosol horizon and primate taxa. Where possible, correlations between sandstones of Basu [7] are noted. Note that if Dalsar represents the Middle Siwaliks, the Sivapithecus specimens recovered could represent S. sivalensis.
Fig 2.
Complete lithostratigraphic column of the Ramnagar section, illustrating major fossil-bearing localities.
Paleomagnetic sampling was conducted across a 190 m interval of the sequence, spanning units S9 to S16. Sandstone unit S1 represents the oldest horizon in the section, while S22 is the youngest. S22, located below Dalsar locality, belongs to the Middle Siwalik formation (see Fig 1c for reference).
Fig 3.
Rock magnetic properties of selected specimens (a) and (b) are the progressive thermal demagnetizations of a composite isothermal remanent magnetization (IRM) [42] that were produced by magnetizing the specimens in a magnetic field Mx, My, and Mz of 1T (high coercivity or hard component), 0.3T (medium coercivity component), and 0.1T (low coercivity or soft component), along three mutually orthogonal axes, respectively.
Fig 4.
Representative Zijderveld diagrams, NRM intensity decay, and equal-area plots showing thermal demagnetization after bedding tilt correction.
(a, b) Reversed and normal polarity trajectories for sandstones. (c, d) Reversed and normal polarity trajectories for paleosols. Solid symbols: downward inclinations; open symbols: upward inclinations. Magnetization intensity scales: × 10 ⁻ ² A/m.
Fig 5.
The Ramnagar section’s characteristic remanence (ChRM) directions.
(a) Bedding-tilt corrected ChRMs of the specimens that roughly converged into two antipodal clusters. (b) Site mean direction for normal and reverse polarity. (c) Normal and reversed site mean directions from Main Section, Dehari Section, Thaplal Locality. (d) Overall mean direction for both reversed and normal polarity. All Solid symbols indicate downward (positive) inclinations, while open symbols denote upward (negative) inclinations.
Table 2.
Mean Paleomagnetic Direction Data.
Fig 6.
Virtual Geomagnetic Pole (VGP) Latitude of S9–S16 Sandstones of Main Section and Individual Sites with Correlation to Local Polarity Stratigraphy.
Fig 7.
a) Magnetic polarity stratigraphy of sandstone units S9 to S16, showing the preferred correlation (2nd) with the Geomagnetic Polarity Time Scale (GPTS) [29].
(b) Three alternative GPTS interpretations proposed and assessed using biostratigraphic constraints from the Ramnagar section.
Fig 8.
Biostratigraphy chart of Ramnagar fauna.
DL- Dalsar, TH- Thaplal, DH- Dheari, BS- Bassi, TP- Tarmin Peak, S1- Sunetar 1, S2- Sunetar 2, MR- Marta, RS- Rashole, KT1 – Kathela 1, KT2- Kathela 2, RM- Ritti-Mitti, KW- Kulwanta. Confirmed faunal occurrences in the stratigraphic context based on [8–20,45].
Fig 9.
Observed magnetic polarity stratigraphy (MPTS) is plotted against the standard geomagnetic polarity timescale (GPTS; Ogg, 2020) to assess sediment accumulation rates (SAR) for preferred Option 2.
(For option 1 & 3, see S2 Fig).