Academia.eduAcademia.edu

Figure 7 – uploaded by Tomas Saks

See full PDFdownloadDownload figure
It is suggested that formation of the internal structure of sandy sediments and rising of the diapirs are strongly coupled. As a result of the formation of the clayey silt or silty clay diapirs overlaying sandy sediments were protruded. Above the topmost portion of diapirs the sandy bed was simultaneously sloped upward and eroded. Sliding over the area situated in the lateral portion of the AGT the active ice immediately sheared off and assimilated the material from the sand bed above rising diapirs and deposited it in subsiding and distally located spaces between the diapirs with only minor admixture of the far-traveled coarse-grained and fine-grained material (Fig. 8). In most cases the silt composing diapirs did not reach the ice- bed interface and were not incorporated in the glacigenic diamicton. The contemporaneous operation of both processes due to diapirism is marked by monoclinally dipping margins of the upper till unit. Figure 8. Principal model showing sediment redistribution at the glacier bed caused by diapiric flow. A — Map view of the material transport from diapir rising areas into interdiapir subsiding spaces. B — Cross section parallel to the axis of the glacial flow. C — Graph showing changes in the glacier sliding velocity.

Figure 8 It is suggested that formation of the internal structure of sandy sediments and rising of the diapirs are strongly coupled. As a result of the formation of the clayey silt or silty clay diapirs overlaying sandy sediments were protruded. Above the topmost portion of diapirs the sandy bed was simultaneously sloped upward and eroded. Sliding over the area situated in the lateral portion of the AGT the active ice immediately sheared off and assimilated the material from the sand bed above rising diapirs and deposited it in subsiding and distally located spaces between the diapirs with only minor admixture of the far-traveled coarse-grained and fine-grained material (Fig. 8). In most cases the silt composing diapirs did not reach the ice- bed interface and were not incorporated in the glacigenic diamicton. The contemporaneous operation of both processes due to diapirism is marked by monoclinally dipping margins of the upper till unit. Figure 8. Principal model showing sediment redistribution at the glacier bed caused by diapiric flow. A — Map view of the material transport from diapir rising areas into interdiapir subsiding spaces. B — Cross section parallel to the axis of the glacial flow. C — Graph showing changes in the glacier sliding velocity.

Related Figures (22)

Figure 1. A — Location of the study area. B — Position of the thesis key sites, position of the OSL dating samples (black squares) and boreholes used (black dots) in geological interpretation of the Pleistocene sequence. C — Position of the key sites of the Apriki glacial tongue. The study area is located at the western Latvia coastal area (Fig. 1A, B and C), where at the Baltic sea coast a chain of the coastal bluffs, that range with interruptions for a distance of almost 90 km, is present. Up to 22 m high coastal bluffs provide insight into Pleistocene glacial and non-glacial deposits. In this study most diverse 5 key sections have been chosen for glaciotectonic investigations, starting from the most northern: Sensala, Gudenieki, Ulmale, Strante and Ziemupe site respectively (Fig. 2 B). Along with these Zitari, Valcenieki,
Figure 1. A — Location of the study area. B — Position of the thesis key sites, position of the OSL dating samples (black squares) and boreholes used (black dots) in geological interpretation of the Pleistocene sequence. C — Position of the key sites of the Apriki glacial tongue. The study area is located at the western Latvia coastal area (Fig. 1A, B and C), where at the Baltic sea coast a chain of the coastal bluffs, that range with interruptions for a distance of almost 90 km, is present. Up to 22 m high coastal bluffs provide insight into Pleistocene glacial and non-glacial deposits. In this study most diverse 5 key sections have been chosen for glaciotectonic investigations, starting from the most northern: Sensala, Gudenieki, Ulmale, Strante and Ziemupe site respectively (Fig. 2 B). Along with these Zitari, Valcenieki,
Figure 3. Generalised section of the Quaternary sequence in western Latvia lowlands and corresponding previously established and reinterpreted chronostratigraphy.
Figure 3. Generalised section of the Quaternary sequence in western Latvia lowlands and corresponding previously established and reinterpreted chronostratigraphy.
Figure 4. Hillshade image of the coastal area near Sensala site. Hillshade image is created from TIN model, with resolution 20x20 m. Vertical resolution is exaggerated 3 times. With question symbols are marked suspected lateral shear moraines. Note that area in between these ridges lie slightly lower than surrounding topography. This figure is unpublished.
Figure 4. Hillshade image of the coastal area near Sensala site. Hillshade image is created from TIN model, with resolution 20x20 m. Vertical resolution is exaggerated 3 times. With question symbols are marked suspected lateral shear moraines. Note that area in between these ridges lie slightly lower than surrounding topography. This figure is unpublished.
Figure 5. Geological cross section of the diapir and thrusted sequence on its northern flank. Thrusts are indicated by the orange dotted lines. Dip of the thrusting as well as asymmetrical shape of the diapir suggest formation of the thrust sequence after or contemporary with diapir formation. Unpublished figure.
Figure 5. Geological cross section of the diapir and thrusted sequence on its northern flank. Thrusts are indicated by the orange dotted lines. Dip of the thrusting as well as asymmetrical shape of the diapir suggest formation of the thrust sequence after or contemporary with diapir formation. Unpublished figure.
Approximately at the middle part of the Ziemupe outcrop section a complex fold- thrust structure assemblage, cross cut by the subglacial shear zone, can be encountered (Fig. 6). Glacial diamicton at the lower part of the outcrop is thrusted and/or forms isometric fold, resembling complex thrusting, detached folding and diapirism processes. As in the Gudenieki and Strante sites, in the Ziemupe site weak, prone to diapirism layer is lower till. It should be noted that compressional stress forming these folds and thrusts is directed in the common NE — SW direction. Lower a diagram corresponds to the syncline in between diamicton slabs, and probably shows folded strata reorientation around till fold below. Figure 6. Complex glaciotectonic succession of thrusted and folded glacial diamicton and silty sand deposits. At the base of the upper till unit sinistral shear zone cross cuts the deformed strata. Deformed edding planes are indicated by white lines, orange dashed line corresponds to supposed thrust plane. Shear zone at the foot of the upper till is indicated by orange dashed line. a diagrams correspond to folded sandy strata. See shovel on the right of the image for scale. Figure published in Paper IL.
Approximately at the middle part of the Ziemupe outcrop section a complex fold- thrust structure assemblage, cross cut by the subglacial shear zone, can be encountered (Fig. 6). Glacial diamicton at the lower part of the outcrop is thrusted and/or forms isometric fold, resembling complex thrusting, detached folding and diapirism processes. As in the Gudenieki and Strante sites, in the Ziemupe site weak, prone to diapirism layer is lower till. It should be noted that compressional stress forming these folds and thrusts is directed in the common NE — SW direction. Lower a diagram corresponds to the syncline in between diamicton slabs, and probably shows folded strata reorientation around till fold below. Figure 6. Complex glaciotectonic succession of thrusted and folded glacial diamicton and silty sand deposits. At the base of the upper till unit sinistral shear zone cross cuts the deformed strata. Deformed edding planes are indicated by white lines, orange dashed line corresponds to supposed thrust plane. Shear zone at the foot of the upper till is indicated by orange dashed line. a diagrams correspond to folded sandy strata. See shovel on the right of the image for scale. Figure published in Paper IL.
\A'4er fs In southern part of the outcrop distinct sinistral shear zone beneath the till layer is present. In the northern part till is eroded by waters of the Baltic Ice Lake, and most probably shear zone was present there as well. Sinistral direction of shear, as indicated by bended offset of shear markers (Fig. 6 and 7) contradicts with overall dextral shearing of sediments near the diapir coupling domains. Results of microlineation measurements in the shear zone confirm S-N shearing direction, which coincides with offset bending direction of the drag folds near the shear zone (Paper ID). Figure 7. Contorted lens of the sand and gravel. diagram is presented for the sincline, and contour stereo diagram for macrofabric measurements in the sand and gravel are presented. Sincline is formed by pressing gravel sediment body in to the unfrozen subglacial substratum. Top of the sincline is cross cut by the sinistral shear zone, at the base of the till, indicated by the pink line. It is proposed that after formation of the syncline glacier became decoupled from its sole. Unpublished figure.
\A'4er fs In southern part of the outcrop distinct sinistral shear zone beneath the till layer is present. In the northern part till is eroded by waters of the Baltic Ice Lake, and most probably shear zone was present there as well. Sinistral direction of shear, as indicated by bended offset of shear markers (Fig. 6 and 7) contradicts with overall dextral shearing of sediments near the diapir coupling domains. Results of microlineation measurements in the shear zone confirm S-N shearing direction, which coincides with offset bending direction of the drag folds near the shear zone (Paper ID). Figure 7. Contorted lens of the sand and gravel. diagram is presented for the sincline, and contour stereo diagram for macrofabric measurements in the sand and gravel are presented. Sincline is formed by pressing gravel sediment body in to the unfrozen subglacial substratum. Top of the sincline is cross cut by the sinistral shear zone, at the base of the till, indicated by the pink line. It is proposed that after formation of the syncline glacier became decoupled from its sole. Unpublished figure.
Table 1. Summarised dating results of all samples from Baltic Sea coast, western Latvia The dating results are summarized in the Table 1. All of the obtained ages suggest sedimentation of the Jrk3 sedimentary unit during the Middle Weichselian interstadial time. The variation of the dating ages in sampling sites must be controlled to some extent by variation of the glaciotectonic deformation that locally can bring near the Earth surface older sediments.
Table 1. Summarised dating results of all samples from Baltic Sea coast, western Latvia The dating results are summarized in the Table 1. All of the obtained ages suggest sedimentation of the Jrk3 sedimentary unit during the Middle Weichselian interstadial time. The variation of the dating ages in sampling sites must be controlled to some extent by variation of the glaciotectonic deformation that locally can bring near the Earth surface older sediments.
Figure 9. Principal model of the pore water pressure fluctuation during the surge of the AGT. A — Initial stage of the AGT advance. Neighbouring to the AGT distal area is still covered by the cold-based, stagnant ice. B — Activating of the AGT leads to build up of the ice masses and melting of the glacier bed and build up of the pore water pressure. C — Surge event triggered by the distraction off the dead ice field. Fast flow of the AGT lead to lowering of the glacier surface and pore water pressures at the glacier bed initiating instabilities in low water conductivity layers. D — Graphs showing principal distribution of the porewater pressures at the glacier bed. Glacier profile and velocity vectors are illustrative and not scaled.
Figure 9. Principal model of the pore water pressure fluctuation during the surge of the AGT. A — Initial stage of the AGT advance. Neighbouring to the AGT distal area is still covered by the cold-based, stagnant ice. B — Activating of the AGT leads to build up of the ice masses and melting of the glacier bed and build up of the pore water pressure. C — Surge event triggered by the distraction off the dead ice field. Fast flow of the AGT lead to lowering of the glacier surface and pore water pressures at the glacier bed initiating instabilities in low water conductivity layers. D — Graphs showing principal distribution of the porewater pressures at the glacier bed. Glacier profile and velocity vectors are illustrative and not scaled.
Figure 10. Theoretical model fluctuation of the pore water pressure and shear strength at the AGT bed with respect to geological structure of the territory. A — Geological cross section parallel to the axes of the AGT. The AGT profile drawing is schematic due to vertical exaggeration. Legend: 1 — Upper Weichselian till unit; 2 — Middle Weichselian till unit; 3 —Saalian till unit; 4 — sand and gravel; 5 - fine sand and silty sand; 6 — middle silt and clayey silt unit; 7 — silty sand; lower silt and clayey silt, 8 — dolomite; 9 — sandstone; 10 — area of proglacial thrusting; 11 — vectors of the pore water migration (not scaled); 13 — boreholes. B — Detail showing mode of the glacier movement. C — Graph showing changes in pore water pressure (Pw) and shear strength () at the glacier bed along the AGT flow line. ee Se A EE Sy RR Glacial bed deformation after the onset of the dolomites is characterized by dropping porewater pressure due to drainage in to the bedrock and divergent ice flow pattern, resulting in a deccelerating ice velocities and formation of the drumlins. Size of the drumlins increases in the downglacier direction, due to enhanced glacier coupling via glacier bed sticky spots (Fig. 10).
Figure 10. Theoretical model fluctuation of the pore water pressure and shear strength at the AGT bed with respect to geological structure of the territory. A — Geological cross section parallel to the axes of the AGT. The AGT profile drawing is schematic due to vertical exaggeration. Legend: 1 — Upper Weichselian till unit; 2 — Middle Weichselian till unit; 3 —Saalian till unit; 4 — sand and gravel; 5 - fine sand and silty sand; 6 — middle silt and clayey silt unit; 7 — silty sand; lower silt and clayey silt, 8 — dolomite; 9 — sandstone; 10 — area of proglacial thrusting; 11 — vectors of the pore water migration (not scaled); 13 — boreholes. B — Detail showing mode of the glacier movement. C — Graph showing changes in pore water pressure (Pw) and shear strength () at the glacier bed along the AGT flow line. ee Se A EE Sy RR Glacial bed deformation after the onset of the dolomites is characterized by dropping porewater pressure due to drainage in to the bedrock and divergent ice flow pattern, resulting in a deccelerating ice velocities and formation of the drumlins. Size of the drumlins increases in the downglacier direction, due to enhanced glacier coupling via glacier bed sticky spots (Fig. 10).
1. attéls. A — Pétijumu vietas novietojums plana. B — Pétito atseguma posmu, OSL paraugoSanas vietu (melni kvadrati) un izmantoto urbumu (melnie punkti) pleistocéna slankopas geologiskas interpretacijas novietojums. C — Apriku ledaja mélei atbilstoSo atseguma posmu novietojums un geomorfologiskas vienibas. rekonstruét un detalizét regionalos ledaja plismas virzienus pétijumu apgabala; (V) Noskaidrot OSL vecumus zemmorénas smilSainajiem nogulumiem.
1. attéls. A — Pétijumu vietas novietojums plana. B — Pétito atseguma posmu, OSL paraugoSanas vietu (melni kvadrati) un izmantoto urbumu (melnie punkti) pleistocéna slankopas geologiskas interpretacijas novietojums. C — Apriku ledaja mélei atbilstoSo atseguma posmu novietojums un geomorfologiskas vienibas. rekonstruét un detalizét regionalos ledaja plismas virzienus pétijumu apgabala; (V) Noskaidrot OSL vecumus zemmorénas smilSainajiem nogulumiem.
2. attéls. Rietumlatvijas pleistocéna slankopas geologiskais griezums (parveidots péc Kalnina et al.,, 2000. Geologisko urbumu novietojumu) skat 1B. att. Teksta iztirzato litologisko vientbu simboli: Sd — Sudrabu slani; Ak - Akmenraga svita; Jrk1, Jrk2, Jrk3 —Jtrkalnes svitas slani.
2. attéls. Rietumlatvijas pleistocéna slankopas geologiskais griezums (parveidots péc Kalnina et al.,, 2000. Geologisko urbumu novietojumu) skat 1B. att. Teksta iztirzato litologisko vientbu simboli: Sd — Sudrabu slani; Ak - Akmenraga svita; Jrk1, Jrk2, Jrk3 —Jtrkalnes svitas slani.
3. attéls. Kvartarsegas generalizéts geologiskais griezums caur Rietumlatvijas lidzenumiem, un tai atbilsto8a, iepriekSé@ja un reinterpretéta nogulumu hronostratigrafija.
3. attéls. Kvartarsegas generalizéts geologiskais griezums caur Rietumlatvijas lidzenumiem, un tai atbilsto8a, iepriekSé@ja un reinterpretéta nogulumu hronostratigrafija.
4. attéls. Sensalas atseguma apkartnes digitala virsmas modela noénojuma attéls. Verikalais mérogs ir palielinats 3 reizes. Ar jautajuma zimém ir atziméts iespéjamas bides sanu morenas. Ievérojiet, ka teritorija starp Siem valniem ir hipsometriski nedaudz zemaka ka arpus tiem. Sis attéls nav publicéts.
4. attéls. Sensalas atseguma apkartnes digitala virsmas modela noénojuma attéls. Verikalais mérogs ir palielinats 3 reizes. Ar jautajuma zimém ir atziméts iespéjamas bides sanu morenas. Ievérojiet, ka teritorija starp Siem valniem ir hipsometriski nedaudz zemaka ka arpus tiem. Sis attéls nav publicéts.
5. attéls. Ziemupes atseguma fragments. Taja redzams diapirs, kam Z sparna ir uzbidijums. Uzbidijumu virsmas ir atzim@tas ar oranzu, punktotu Iiniju. Uzbidijuma virsmu krituma lenkis, ka ari diapira krokas forma norada uz to vienlaicigu veidoSanos. Nepublicéts attéls. (6. att.). Domajams, ta atspogulo krokotu nogulumu struktirelementu p§arorientaciju ap apakSéjo diamiktona kroku.
5. attéls. Ziemupes atseguma fragments. Taja redzams diapirs, kam Z sparna ir uzbidijums. Uzbidijumu virsmas ir atzim@tas ar oranzu, punktotu Iiniju. Uzbidijuma virsmu krituma lenkis, ka ari diapira krokas forma norada uz to vienlaicigu veidoSanos. Nepublicéts attéls. (6. att.). Domajams, ta atspogulo krokotu nogulumu struktirelementu p§arorientaciju ap apakSéjo diamiktona kroku.
6. attéls. Komplekss morénas un aleiritiskas smilts glaciotektonisko uzbidijumu un kroku struktiiru komplekss. AugSéjas morénas pamatné ir novérojama sinistrala bides zona, kas noSke] deforméto slankopu. Baltas linijas atspogulo deformétas noslanojumu virsmas; partraukta oranza linija atbilst domajamam uzbidijuma virsmam. Bides zona aug8éjas morénas pamatné ir atziméta ar oranZzu partrauktu Itniju. 2 diagrammas sastadita krokotajiem aleiritiskas smilts slaniem. Nepublicéts attéls.
6. attéls. Komplekss morénas un aleiritiskas smilts glaciotektonisko uzbidijumu un kroku struktiiru komplekss. AugSéjas morénas pamatné ir novérojama sinistrala bides zona, kas noSke] deforméto slankopu. Baltas linijas atspogulo deformétas noslanojumu virsmas; partraukta oranza linija atbilst domajamam uzbidijuma virsmam. Bides zona aug8éjas morénas pamatné ir atziméta ar oranZzu partrauktu Itniju. 2 diagrammas sastadita krokotajiem aleiritiskas smilts slaniem. Nepublicéts attéls.
a, a, i ioe Bides zonas raSanas izraisija lidz pat 2 m bieza deformacijas slana veidoSanos, kas atspogulojas linearitates parorientacija diamiktona zem bides zonas (3. att., Publikacija II). AugSéjas morénas makrolinearitatei ir labi izteikts ZZA-DDR virziena vérsts maksimums (01=0.675; 62=0.256), kas labi saskan ar regionalo ledaja plismas virzienu Saja teritorija (Gaigalas et al., 1967; Punkari, 1997; Boulton et al., 2001; Zelés, Markots, 2004). Savukart makrolinearitate apakSéja diamiktona nav tik labi izteikta (o;=0.443; 0o2=0.370). Lielas o2 vertibas norada uz lineamentu izkliedi kopiga plakné, kas liecina par morénas lineamentu parorientaciju bides deformacijas rezultata. 7. attéls. Deforméta grants un olu materiala léca. 1 diagramma atspogulo sinklinalas krokas krokas plakniskos elementus, kontirdiagramma ataino grants — olu materiala makrolinearitati. Sinklinala kroka ir veidojusies iespiezot grants — olu materiala kermeni izkusu84 zmeledaja substrata. Sinklinales virsmu, mor€nas pamatné, noSke] sinistrala bides zona, ka sir atziméta ar rozigu Itniju. Nepublicéts attéls.
a, a, i ioe Bides zonas raSanas izraisija lidz pat 2 m bieza deformacijas slana veidoSanos, kas atspogulojas linearitates parorientacija diamiktona zem bides zonas (3. att., Publikacija II). AugSéjas morénas makrolinearitatei ir labi izteikts ZZA-DDR virziena vérsts maksimums (01=0.675; 62=0.256), kas labi saskan ar regionalo ledaja plismas virzienu Saja teritorija (Gaigalas et al., 1967; Punkari, 1997; Boulton et al., 2001; Zelés, Markots, 2004). Savukart makrolinearitate apakSéja diamiktona nav tik labi izteikta (o;=0.443; 0o2=0.370). Lielas o2 vertibas norada uz lineamentu izkliedi kopiga plakné, kas liecina par morénas lineamentu parorientaciju bides deformacijas rezultata. 7. attéls. Deforméta grants un olu materiala léca. 1 diagramma atspogulo sinklinalas krokas krokas plakniskos elementus, kontirdiagramma ataino grants — olu materiala makrolinearitati. Sinklinala kroka ir veidojusies iespiezot grants — olu materiala kermeni izkusu84 zmeledaja substrata. Sinklinales virsmu, mor€nas pamatné, noSke] sinistrala bides zona, ka sir atziméta ar rozigu Itniju. Nepublicéts attéls.
1. tabula. Baltijas jtiras stavkrasta atsegto zemmorénas smilts nogulumu OSL datéSanas rezultati.
1. tabula. Baltijas jtiras stavkrasta atsegto zemmorénas smilts nogulumu OSL datéSanas rezultati.
No rezultatiem ir secinams, ka smilSaino nogulumu deformacija un diapira struktiru veidoSanas ir savstarpéji saistita. Rodoties un attistoties diapira struktiram, tas noSkéla parsedzoSos smilSainos nogulumus, ka art pacéla tos tuvak ledaja gultnei. Virs diapira strukttru virsotném smilSainais materials, lidz ko tas nonaca ledaja-gultnes kontaktzona, tika erodéts. Sis materials tika asimiléts ledaja un transportéts distala virziend esoSas starp diapiru ieplakas virziena un nogulsnéts taja. Tadéjadi veidojas lokala materiala morénas akrécijas lécas (8. att.). Vairuma gadijumu diapira struktiras tomér nesasniedza ledaja-gultnes 8. attéls. Shematisks materiala pardales un diaptru pliismas modelis Apriku ledus méles gultné. A — Materiala transports no diapiru struktiru virsotném uz starp diapiru ieplakam planskatijuma. B — Griezums, paraléli ledus pltismas virzienam. C — Ledus pliismas atruma salidzinoSo izmainu shematisks grafiks.
No rezultatiem ir secinams, ka smilSaino nogulumu deformacija un diapira struktiru veidoSanas ir savstarpéji saistita. Rodoties un attistoties diapira struktiram, tas noSkéla parsedzoSos smilSainos nogulumus, ka art pacéla tos tuvak ledaja gultnei. Virs diapira strukttru virsotném smilSainais materials, lidz ko tas nonaca ledaja-gultnes kontaktzona, tika erodéts. Sis materials tika asimiléts ledaja un transportéts distala virziend esoSas starp diapiru ieplakas virziena un nogulsnéts taja. Tadéjadi veidojas lokala materiala morénas akrécijas lécas (8. att.). Vairuma gadijumu diapira struktiras tomér nesasniedza ledaja-gultnes 8. attéls. Shematisks materiala pardales un diaptru pliismas modelis Apriku ledus méles gultné. A — Materiala transports no diapiru struktiru virsotném uz starp diapiru ieplakam planskatijuma. B — Griezums, paraléli ledus pltismas virzienam. C — Ledus pliismas atruma salidzinoSo izmainu shematisks grafiks.
9. attéls. Portdens spiediena svarstibu principialais modelis Apriku ledus méles uzpludu (sérdza) laika. A — Apriku ledus méles uzvirziSanas sakums. Piegulo8a distala ledus masa Saja etapa ir joprojam piesalusi pie gultnes; B — Apriku ledus méles uzplidi izraisa ledus masu uzkraSanos uz frontalas aktiva-stagnanta ledaja robeZas un poridens spiedienu pieaugumu zemledaja substrata; C — Apriku ledusméles uzplidi, kas tika izraisiti iznicinot priekSa esoS4 stagnanta ledus lauku. ALM méles strauja uzvirziSanas noveda pie straujas ledaja virsmas kriSanas, un attiectgi strauju poriidens spiedienu kri§anos zem ledaja, kas izraisija nestabilitaSu raSanos nesaistitos, vaji caurlaidigos zemledaja nogulumos.
9. attéls. Portdens spiediena svarstibu principialais modelis Apriku ledus méles uzpludu (sérdza) laika. A — Apriku ledus méles uzvirziSanas sakums. Piegulo8a distala ledus masa Saja etapa ir joprojam piesalusi pie gultnes; B — Apriku ledus méles uzplidi izraisa ledus masu uzkraSanos uz frontalas aktiva-stagnanta ledaja robeZas un poridens spiedienu pieaugumu zemledaja substrata; C — Apriku ledusméles uzplidi, kas tika izraisiti iznicinot priekSa esoS4 stagnanta ledus lauku. ALM méles strauja uzvirziSanas noveda pie straujas ledaja virsmas kriSanas, un attiectgi strauju poriidens spiedienu kri§anos zem ledaja, kas izraisija nestabilitaSu raSanos nesaistitos, vaji caurlaidigos zemledaja nogulumos.
10. attéls. Teorétisks portidens spiediena un bides sprieguma fluktuacijas modelis Apriku ledus méles gultné. A — Geologiskais griezums paraléli Apriku ledus méles ass linijai. Apriku ledus méles profils ir attélots shematiski. Legenda: 1 — Aug8éja morénas slankopa; 2 — Vidéj4 morénas slankopa; 3 —Apak8éja morénas slankopa; 4 — smilts un grants; 5 — smalkgraudaina un aleiritiska smilts; 6 — vidéja aleir’’ita un malaina aleirita slankopa; 7 — aleiritiska smilts; apakSé@jais aleirits un malainais aleirits, 8 — dolomits; 9 — smilSakmens; 10 — proglacialo uzbidijumu zona; 11 — poridenu m,igracijas vektori (neatbilst mérogam); 13 — urbumi. B — Detala — ledaja plismas atruma sadalijums gultné. C — Grafiks, kas parada portidens spiediena (Pw) un bides sprieguma () kvalitativas izmainas Apriku ledus méles gultné.
10. attéls. Teorétisks portidens spiediena un bides sprieguma fluktuacijas modelis Apriku ledus méles gultné. A — Geologiskais griezums paraléli Apriku ledus méles ass linijai. Apriku ledus méles profils ir attélots shematiski. Legenda: 1 — Aug8éja morénas slankopa; 2 — Vidéj4 morénas slankopa; 3 —Apak8éja morénas slankopa; 4 — smilts un grants; 5 — smalkgraudaina un aleiritiska smilts; 6 — vidéja aleir’’ita un malaina aleirita slankopa; 7 — aleiritiska smilts; apakSé@jais aleirits un malainais aleirits, 8 — dolomits; 9 — smilSakmens; 10 — proglacialo uzbidijumu zona; 11 — poridenu m,igracijas vektori (neatbilst mérogam); 13 — urbumi. B — Detala — ledaja plismas atruma sadalijums gultné. C — Grafiks, kas parada portidens spiediena (Pw) un bides sprieguma () kvalitativas izmainas Apriku ledus méles gultné.
580 California St., Suite 400
San Francisco, CA, 94104
© 2025 Academia. All rights reserved