@article{fdi:010081327,
  title = {{A}n assessment of competing factors for fluvial incision : an example of the late {Q}uaternary exorheic {M}oyobamba basin, {P}eruvian {S}ubandes},
  author = {{V}iveen, {W}. and {S}anjurjo-{S}anchez, {J}. and {B}aby, {P}atrice and {G}onzalez-{M}oradas, {M}. {D}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}hree competing factors for late {Q}uaternary fluvial incision in the {M}oyobamba piggyback basin, located in the northeastern {P}eruvian {S}ubandes, were investigated, namely base-level change as a result of basin opening, changes in the ratio sediment load:discharge ({Q}(s): {Q}(w)) controlled by orbital and suborbital climate cyclicity, and thrust-related tectonic uplift. {T}o assess the relative importance of these factors, the fluvial terrace staircases of five rivers were studied in terms of their sedimentology, stratigraphy and geomorphology. {A} new dataset of eight {O}ptically {S}timulated {L}uminescence ({OSL}) and four {C}-14 ages shows that the final phase of endorheic alluvial fan aggradation lasted until 18.0 +/- 1.4 ka, after which basin-wide incision occurred. {I}ncision at the basin outlet as a result of adaptation to the new base level is decoupled from the observed incision in the middle and upper parts of the basin. {T}here, incision is the result of a northwestward increase in uplift related to movements of the {C}erro {B}lanco thrust at the western border of the {M}oyobamba basin. {I}ncision was continuous from 18 +/- 1.4 ka until 10.3 +/- 0.7 ka without terrace formation, but between 10.3 +/- 0.7 ka and 5.5 +/- 0.4 ka up to four terrace levels were formed. {D}eposition of fluvial terrace sediments may have occurred during short periods characterised by a more intense {S}outh {A}merican {S}ummer {M}onsoon ({SASM}) controlled by suborbital climate cyclicity, but a more precise age control is needed to confirm this theory. {P}recession-controlled, increased {H}olocene aridification between 10.3 +/- 0.7 ka and 5.5 +/- 0.4 ka may have resulted in a decrease in the ratio {Q}(s): {Q}(w) leading to a five-fold increase in fluvial incision rates of up to 6.0 mm a(-1) and flattening of terrace profile gradients with rates of up to 2.6 mm a(-1). {A}fter 5.5 +/- 0.4 ka, rates dropped again. {O}ver longer timescales, movement of the {C}erro {B}lanco thrust caused basin-wide uplift and fluvial incision at a more constant pace. {D}uring the past similar to 20 ka, incision increases from the southwest basin border towards the northwestern basin border with corresponding uplift rates increasing from 0.2(-0.2)(+0.3) mm a(-1) to 2.1(-0.2)(+0.2) mm a(-1); and with shortening rates increasing northwestward from 0.2(-0.2)(+0.4) mm a(-1) to 2.8(-0.2)(+0.3) mm a(-1). {T}he highest, presented uplift rates are in agreement with independently published data for our study area. {O}ur data shows that over longer timescales of similar to 20 ka, incision rates can be used as proxies for tectonic uplift, but over shorter timescales incision rates may be seriously affected by climate change and cannot be used to infer uplift rates. {I}t is further suggested that continuous uplift and erosion of the {C}erro {B}lanco thrust system, and subsequent sedimentation in the basin, in combination with increased precipitation during {H}einrich events 1 and 2 and the {L}ast {G}lacial {M}aximum ({LGM}), led to basin overflow. {S}imultaneously, river capture through headward erosion, guided by strike-slip faulting, may have led to the definitive opening up of the {M}oyobamba basin. {T}o our knowledge, this is the first time that late {Q}uaternary basin opening has been demonstrated for the {S}outh {A}merican {A}ndes and one of the few, known cases worldwide.},
  keywords = {{A}ndes ; {F}luvial terraces ; {A}mazon ; {OSL} dating ; {T}ectonogeomorphic indices ; {PEROU} ; {ANDES} ; {MOYOBAMBA} {BASSIN}},
  booktitle = {},
  journal = {{G}lobal and {P}lanetary {C}hange},
  volume = {200},
  numero = {},
  pages = {103476 [24 ]},
  ISSN = {0921-8181},
  year = {2021},
  DOI = {10.1016/j.gloplacha.2021.103476},
  URL = {https://www.documentation.ird.fr/hor/fdi:010081327},
}