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<p>The Himalayan Mountain range is the most prominent and active intracontinental range in the world. The outer part of this range is marked by the Himalayan foreland basin (HFB) in south that resulted due to the thrust loading and subsidence with synorogenic sedimentation from the hinterland. The lowermost part of the HFB is marked by the molassic sediments of “Siwalik” which thins out to the south. The time frame between 11Ma to 6 Ma (mid to late Miocene) is critical to understand the changes related to monsoon and vegetation as there is no detailed record or systematic study of late Cenozoic weathering and paleopedogenesis in fluvial sediments of the HFB. In the present study, we present a high-resolution paleopedological record of the paleosols along a traverse of ~ 1.8 km in the Kotla-Brail section of the Kangra sub-basin of the HFB. In the field, the paleosols are characterized by 1-2 m thick Bw, Bt, Bk, Bss, Bk horizons, rhizocretions, pedogenic carbonates (PC), and Fe/Mn mottles and concretions. The paleosols in the Lower Siwaliks show a dominance of 2.5 Y and 5 YR hue, whereas in the Middle Siwaliks they are defined by 5 YR and 7.5 YR hue. Micromorphology of these paleosols confirmed varying degrees of weathering, and paleopedogenesis showing a blocky structure, clay coatings, biogenic activity, and diffused impure micritic nodules as PC in the Bw and Bt, Btk horizons. These pedofeatures are more strongly developed in paleosols of the Lower Siwaliks than in comparison to weakly-moderately paleosols of the Middle Siwaliks.</p> <p>Clay mineralogy determined based on XRD study of the total (<2 µm) fine clay (<0.2 µm) fractions of these paleosols is characterized by the dominance of smectite, vermiculite, and mixed-layer minerals in paleosols of the Lower Siwalik. The clay mineral assemblage shows a  decrease in the abundance of smectite and increase of kaolinite towards the transitions to Middle Siwalik at ~10 Ma. This also shows transformation of the smectite and vermiculite to interstratified clays at about ~8 Ma. After ~8.5 – 8.0 Ma, the paleosols are again marked an increase of the amount of smectite, vermiculite, and mixed-layer minerals in paleosols of the Middle Siwalik towards their transitions to Upper Siwalik. The varying intensity of weathering, paleopedogenesis, and clay mineral assemblage of the paleosols in the Lower and Middle Siwalik suggest fluctuating climatic conditions that evolved from initial semi-arid to sub-humid at ~11 Ma that to higher precipitation at ~8.5 to 8 Ma then again to semi-arid to arid conditions at ~6.5 Ma.</p> <p> </p> <p>Keywords: Himalayan Foreland Basin (HFB), Siwalik, Paleosols, Micromorphology, Clay Minerals</p>

<p>In the present study we report paleopedology of the fluvial sequences of the Siwalik Group in the Himalayan Foreland Basin, NW Himalaya that formed during ~12 Ma -5.5 Ma. The paleosols formed during this time period are critical to understand weathering and paleopedogenic processes during the evolution of foreland basin over the entire Himalayan range. This work highlights field-characteristics, micromorphology, clay mineralogy, and geochemistry of the ~0.5 km thick Lower Siwalik and ~1.7 km thick Middle Siwalik successions along the Katilu Khad, Kangra sub-basin. In the field, the paleosols are characterized by 1-2 m thick Bw, Bt, Bk, Bss, and BC horizons, blocky and wedge-shaped pedogenic structures, root traces, color mottling, Fe-Mn oxide concretions, slickensides, pedogenic CaCO<sub>3 </sub>(PC), and bioturbation features. </p> <p>Micromorphological observations show the dominance of moderate to well-developed paleopedofeatures in paleosols of the Lower Siwalik in contrast to the moderately to weakly-developed paleopedofeatures in paleosols of the Middle Siwalik. The comparative analysis of various pedogenic features i.e., PC, illuvial clay, mottles, Fe-Mn concretions, microstructures, and bioturbation features confirmed varying degree of the paleopedogenic maturity in the paleosols at different intervals of the Siwalik successions.</p> <p>Clay mineralogy of the total clay (<2 μm) and fine clay fraction (< 0.2 μm) of the Lower and Middle Siwalik paleosols suggests varying chemical weathering of silicates and change of paleoclimatic conditions during paleopedogenic processes during this time period. The clay mineral assemblage of the total clay and fine clay fraction show the varying distribution of illite, chlorite, kaolinite, smectite, vermiculite and interstratified clay minerals in these paleosols. Large amounts of smectite together with pedogenic carbonates in part of the Lower Siwalik at 12.0 Ma, and at 10.9 Ma and in Middle Siwalik at 9.2 Ma, and at 5.5 Ma suggest arid to semiarid dry climatic conditions Whereas, dominance of kaolin, illuvial features, and dissolution of pedogenic carbonates suggests sub-humid to humid climatic condition at 11.6 Ma, 8.5 Ma, 7.1 Ma, and at 6.5 Ma.</p> <p>The bulk geochemistry of the paleosols also confirmed varying degree of pedogenic weathering showing high CIA and CIA-K (CIW) values and ~ 800 mm to 1400 mm MAP for paleosols of the Lower and Middle Siwalik. The high MAP (~ 1200 mm to 1400 mm) at ~11.6 Ma, ~8.5 to 8.0 Ma, and 7.1 to 6.5 Ma in paleosols of the Lower Siwalik and Middle Siwalik correspond to increased chemical weathering and paleopedogenesis. While the intervening periods correspond to less MAP (~800 mm to 1100 mm) with large amount PC and less chemical weathering. Based on micromorphology, clay mineralogy, and geochemical characteristics of the paleosols it is interpreted that climate change during ~12 Ma to 5.5 Ma is characterized by humid (11.6 Ma) to semiarid (11.0 Ma to 8.5 Ma), and humid-subhumid (8.5 Ma to 6.5 Ma) in response to Himalayan orogeny and its linkage to regional and global atmospheric conditions.</p> <p>Keywords: Himalayan Foreland Basin, Paleosols, Siwalik, Micromorphology, Clay mineralogy, Geochemistry</p>

The northwestern coast is located in the western desert of Egypt. The whole region is under hot arid conditions. Four landforms were identified and soils the area is sufficient for initiated cultivation of figs and the associated industrial and economic activities. Abundant runoff, and water shed practices the lands are promising for agricultural expansion. Sixteen soil profiles representing the four landforms of coastal plain, windblown formation, piedmont like plains and plateau formation were taken to study the morphological, chemical, physical and mineralogical characteristics of the area. and explore possible .

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