the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 11 Mar 2022
An Early-Mid Holocene process of regional desertification recorded in aeolian sediments from the northern slope of the middle Himalayan Mountains
Abstract. Aeolian sediments, a sensitive paleoclimatic and paleoenvironmental archive, are widely distributed over the Tibetan Plateau. In the northern slope of the Himalayan Mountains, however, the potential linkages between the aeolian processes, climatic changes, and the processes of desertification during the Holocene are not well understood. Here, we use an aeolian record from the northern slope of the middle Himalayan Mountains to investigate the influences of paleoclimate and paleoenvironment during the Early-Mid Holocene through the optically stimulated luminescence (OSL) dating, magnetic parameters, color variations, scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), and grain size parameters. Glacial sediments, weathering products, the surface of lack of vegetation cover, and alluvium and ancient lacustrine sediments had provided the sources for the aeolian sediments. The strengthened Indian monsoon intensity, dry and warm climate, and sparse vegetation cover accelerated the rapid expansion of desertification between ~11 and 9.6 ka B.P.. The Indian monsoon intensity weakened between 9.6 and 6.3 ka B.P., the warm and humid climate and increased vegetation cover decelerated the rapid expansion of desertification. Influenced by the weakened Indian monsoon intensity, warm and humid climate, increased vegetation cover, and limited sources, the desertification decelerated further between 6.3 and ~4.5 ka B.P.. Further, the linkage and interplay between changes in the Indian monsoon, vegetation cover, sources, and landforms play a key role in aeolian processes and regional processes of desertification in the northern slope Himalayan Mountains during the Early-Mid Holocene.
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RC1: 'Comment on cp-2022-17', Anonymous Referee #1, 12 Mar 2022
This ms attempts to use ‘aeolian sediments’ to document the Holocene history of regional desertification on the northern slope of the middle Himalayan Mountains.
I do not think the ms is worthy being considered for publication in CP, because of the following shortcomings.
Firstly, the topic is very regional and even local, lacking necessary support for large regional or global interpretations.
Secondly, the concept of ‘aeolian sediments’is not clear. The studied sediments are loess deposits or dune deposits? These two types of sediments are radically different in climate/environmental significance, as is the basis of all the interpretations and conclusions. Fig 2 and the descriptions in the text/figures do not support for loess deposits because of the topography, the gravels within the section, the sandy texture with the mean grain size ranges from 90.71 μm to 230.65 μm. The field pictures and descriptions (e.g. Lines 66-67: Any sedimentary beddings were not found in the aeolian sands of this profile.) are also unsupportive for eolian dune deposits. Rather, the main features outlined in the text tend to support an origin of galley water-lain deposits (at least water-reworked sediments). Such kind of deposits cannot be treated as environmental records for addressing paleoenvironmental histories. The relevant interpretations based on such records are of great uncertainties.
Thirdly, the used paleoenvironmental proxies are mostly ambiguous lacking explicit environmental significance. They are sometimes used for loess studies, but are not necessarily applicable for the studied sediments. The main conclusions (Lines 18-20:‘the strengthened Indian monsoon intensity, dry and warm climate, and sparse vegetation cover accelerated the rapid expansion of desertification between ~11 and 9.6 ka B.P, …, The Indian monsoon intensity weakened between 9.6 and 6.3 ka B.P.’) greatly differs from the earlier reported histories for Indian monsoon, while these are not discussed at all the the ms.
Citation: https://doi.org/10.5194/cp-2022-17-RC1 -
RC2: 'Comment on cp-2022-17', Anonymous Referee #2, 14 Apr 2022
I read in-depth the Manuscript " An Early-Mid Holocene processes of regional desertification..."
I find the practice in this manuscript as problematic, although it appears in recent years again and again in the literature. In my opinion, the procedure presented is weak and has no real scientific value.
This paper takes a very small exposure (even if it comes from an interesting location, provides overlapping-in-range four OSL ages, and numerous grain size analyses to claim desertification and correlate it with detailed global high-resolution data. One small exposure of fine eolian sand cannot be the basis for claiming desertification and even not drying or a drought phase (which I find the authors mixing between them, something that seems taken too lightly). Furthermore, the assumption that it is the result of drying avoids other possibilities such as higher winds...).
The overlap of ages, which is common with OSL, cannot resolve the chronology in the way the authors wish. Therefore, the data they supply are insufficient to support their discussion. they apply the ages according to a central trend (inset in fig 2a). this is a weak practice. also, the overlap between the two lower ages precludes any chronological claim. and the thousands of years of overlap is again very problematic. And from this to go to global correlation makes it an arm-waving paper, rather than an in-depth paper.
Citation: https://doi.org/10.5194/cp-2022-17-RC2
Status: closed
-
RC1: 'Comment on cp-2022-17', Anonymous Referee #1, 12 Mar 2022
This ms attempts to use ‘aeolian sediments’ to document the Holocene history of regional desertification on the northern slope of the middle Himalayan Mountains.
I do not think the ms is worthy being considered for publication in CP, because of the following shortcomings.
Firstly, the topic is very regional and even local, lacking necessary support for large regional or global interpretations.
Secondly, the concept of ‘aeolian sediments’is not clear. The studied sediments are loess deposits or dune deposits? These two types of sediments are radically different in climate/environmental significance, as is the basis of all the interpretations and conclusions. Fig 2 and the descriptions in the text/figures do not support for loess deposits because of the topography, the gravels within the section, the sandy texture with the mean grain size ranges from 90.71 μm to 230.65 μm. The field pictures and descriptions (e.g. Lines 66-67: Any sedimentary beddings were not found in the aeolian sands of this profile.) are also unsupportive for eolian dune deposits. Rather, the main features outlined in the text tend to support an origin of galley water-lain deposits (at least water-reworked sediments). Such kind of deposits cannot be treated as environmental records for addressing paleoenvironmental histories. The relevant interpretations based on such records are of great uncertainties.
Thirdly, the used paleoenvironmental proxies are mostly ambiguous lacking explicit environmental significance. They are sometimes used for loess studies, but are not necessarily applicable for the studied sediments. The main conclusions (Lines 18-20:‘the strengthened Indian monsoon intensity, dry and warm climate, and sparse vegetation cover accelerated the rapid expansion of desertification between ~11 and 9.6 ka B.P, …, The Indian monsoon intensity weakened between 9.6 and 6.3 ka B.P.’) greatly differs from the earlier reported histories for Indian monsoon, while these are not discussed at all the the ms.
Citation: https://doi.org/10.5194/cp-2022-17-RC1 -
RC2: 'Comment on cp-2022-17', Anonymous Referee #2, 14 Apr 2022
I read in-depth the Manuscript " An Early-Mid Holocene processes of regional desertification..."
I find the practice in this manuscript as problematic, although it appears in recent years again and again in the literature. In my opinion, the procedure presented is weak and has no real scientific value.
This paper takes a very small exposure (even if it comes from an interesting location, provides overlapping-in-range four OSL ages, and numerous grain size analyses to claim desertification and correlate it with detailed global high-resolution data. One small exposure of fine eolian sand cannot be the basis for claiming desertification and even not drying or a drought phase (which I find the authors mixing between them, something that seems taken too lightly). Furthermore, the assumption that it is the result of drying avoids other possibilities such as higher winds...).
The overlap of ages, which is common with OSL, cannot resolve the chronology in the way the authors wish. Therefore, the data they supply are insufficient to support their discussion. they apply the ages according to a central trend (inset in fig 2a). this is a weak practice. also, the overlap between the two lower ages precludes any chronological claim. and the thousands of years of overlap is again very problematic. And from this to go to global correlation makes it an arm-waving paper, rather than an in-depth paper.
Citation: https://doi.org/10.5194/cp-2022-17-RC2
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