El Niño forcing on 10 Be-based surface denudation rates in the northwestern

article Be denudation rates Landscape transience High magnitude precipitation events provide large contributions to landscape formation and surface denudation in arid environments. Here, we quantify the precipitation-dependent geomorphic processes within the Rio Piura drainage basin located on the Western Escarpment of the northern Peruvian Andes at 5°S latitude. In this region, monsoonal easterly winds bring precipitation to the N3000 m asl high headwaters, from where the annual amount of precipitation decreases downstream toward the Pacific coast. Denudation rates are highest in the knickzones near the headwaters, ~200-300 mm ky �1 , and sediment discharge is limited by the transport capacity of the channel network. Every few years, this situation is perturbed by westerly, wind-driven heavy precipitation during El Nino events and results in supply-limited sediment discharge as indicated by bedrock channels. The detailed analysis of the stream-long profiles of two river basins within the Rio Piura catchment reveals a distinct knickzone in the transition zone between the easterly and westerly climatic influences, suggesting an En Nino forcing on the longitudinal channel profiles over at least Holocene timescales. Measured trunk stream catchment-wide denudation rates are up to ca. 300 mm ky �1 and decrease successively downstream along the river profiles. Denudation rates of tributary rivers are ca. 200 mm ky �1 near the plateau and show a stronger downstream decreasing trend than trunk stream rates. This suggests that the landscape is in a transient stage of local relief growth, which is driven by fluvial incision. This corroborates the results of paleoclimate studies that point towards higher El Nino frequencies during the past ca. 3000 years, leading to higher runoff and more erosion in the trunk channel compared to the hillslopes and thus growth of local relief. Downstream increases in channel gradient spatially coincide with the reaches of highest precipitation rates during El Nino events, we therefore interpret that Holocene landscape evolution has largely been controlled by climate. The ky-timescale of the 10

[1]  F. Blanckenburg,et al.  Determination of the 10Be half-life by multicollector ICP-MS and liquid scintillation counting , 2010 .

[2]  D. Rieke-Zapp,et al.  Relationships between landscape morphology, climate and surface erosion in northern Peru at 5°S latitude , 2009 .

[3]  Fritz Schlunegger,et al.  Drainage basin response to climate change in the Pisco valley, Peru , 2009 .

[4]  T. Ehlers,et al.  Influence of Andean uplift on climate and paleoaltimetry estimates , 2009 .

[5]  R. Wieler,et al.  Complex multiple cosmogenic nuclide concentration and histories in the arid Rio Lluta catchment, northern Chile , 2009 .

[6]  K. Whipple.  The influence of climate on the tectonic evolution of mountain belts. , 2009 .

[7]  V. Vanacker,et al.  Effects of terrain smoothing on topographic shielding correction factors for cosmogenic nuclide‐derived estimates of basin‐averaged denudation rates , 2009 .

[8]  W. Dietrich,et al.  Controls on the spacing of first-order valleys , 2008 .

[9]  F. Schlunegger,et al.  Channelized and hillslope sediment transport and the geomorphology of mountain belts , 2008 .

[10]  Bodo Bookhagen,et al.  Orographic barriers, high‐resolution TRMM rainfall, and relief variations along the eastern Andes , 2008 .

[11]  F. Schlunegger,et al.  Possible flexural accommodation on the eastern edge of the Altiplano in relation to focussed erosion in the Rio La Paz drainage system , 2007 .

[12]  K. Whipple,et al.  Uplift of the western margin of the Andean plateau revealed from canyon incision history, southern Peru , 2007 .

[13]  B. Rein.  How do the 1982/83 and 1997/98 El Niños rank in a geological record from Peru? , 2007 .

[14]  Susan Ivy-Ochs,et al.  Denudation rates and a topography-driven rainfall threshold in northern Chile: Multiple cosmogenic nuclide data and sediment yield budgets , 2007 .

[15]  F. Schlunegger,et al.  Scale of relief growth in the forearc of the Andes of Northern Chile (Arica latitude, 18°S) , 2006 .

[16]  Luc Ortlieb,et al.  Quaternary coastal uplift along the Talara Arc (Ecuador, Northern Peru) from new marine terrace data , 2006 .

[17]  F. Blanckenburg.  The control mechanisms of erosion and weathering at basin scale from cosmogenic nuclides in river sediment , 2005 .

[18]  F. Pazzaglia,et al.  Climatic influences on profile concavity and river incision , 2005 .

[19]  Rolf Aalto,et al.  Erosion rates driven by channel network incision in the Bolivian Andes , 2005 .

[20]  Marcelo H. García,et al.  Fault-related folding, drainage network evolution and valley incision during the Neogene in the Andean Precordillera of Northern Chile , 2005 .

[21]  P. Kubik,et al.  Cosmogenic nuclide evidence for low weathering and denudation in the wet, tropical highlands of Sri Lanka , 2004 .

[22]  C. Riebe,et al.  Erosional and climatic effects on long-term chemical weathering rates in granitic landscapes spanning diverse climate regimes ☆ , 2004 .

[23]  K. Whipple.  BEDROCK RIVERS AND THE GEOMORPHOLOGY OF ACTIVE OROGENS , 2004 .

[24]  D. Montgomery,et al.  Coupled spatial variations in precipitation and long-term erosion rates across the Washington Cascades , 2003, Nature.

[25]  T. P. Ojha,et al.  Decoupling of erosion and precipitation in the Himalayas , 2003, Nature.

[26]  Dimitri Lague,et al.  Links between erosion, runoff variability and seismicity in the Taiwan orogen , 2003, Nature.

[27]  D. Sandweiss.  Terminal Pleistocene through Mid-Holocene archaeological sites as paleoclimatic archives for the Peruvian coast , 2003 .

[28]  Amy C. Clement,et al.  The climate of the Altiplano: observed current conditions and mechanisms of past changes , 2003 .

[29]  D. Montgomery,et al.  Effects of orographic precipitation variations on the concavity of steady-state river profiles , 2002 .

[30]  Peter Molnar,et al.  Climate change, flooding in arid environments, and erosion rates , 2001 .

[31]  A. Clement,et al.  Variation in Holocene El Niño frequencies: Climate records and cultural consequences in ancient Peru , 2001 .

[32]  J. Stone.  Air pressure and cosmogenic isotope production , 2000 .

[33]  C. Riebe,et al.  Erosional equilibrium and disequilibrium in the Sierra Nevada, inferred from cosmogenic 26Al and 10Be in alluvial sediment , 2000 .

[34]  David A. Seal,et al.  The Shuttle Radar Topography Mission , 2007 .

[35]  K. Whipple,et al.  Geomorphic limits to climate-induced increases in topographic relief , 1999, Nature.

[36]  G. Tucker,et al.  Dynamics of the stream‐power river incision model: Implications for height limits of mountain ranges, landscape response timescales, and research needs , 1999 .

[37]  R. Garreaud.  Multiscale Analysis of the Summertime Precipitation over the Central Andes , 1999 .

[38]  Mark B. Abbott,et al.  An ;15,000-Year Record of El Nino—Driven Alluviation in Southwestern Ecuador , 1999 .

[39]  Colin P. Stark,et al.  Landslide-driven drainage network evolution in a pre-steady-state mountain belt: Finisterre Mountains, Papua New Guinea , 1998 .

[40]  A. Aldahan,et al.  A HIGH-RESOLUTION 10BE PROFILE FROM DEEP SEA SEDIMENT COVERING THE LAST 70KA : INDICATION FOR GLOBALLY SYNCHRONIZED ENVIRONMENTAL EVENTS , 1998 .

[41]  Jean Braun,et al.  Numerical modelling of landscape evolution on geological time‐scales: a parameter analysis and comparison with the south‐eastern highlands of Australia , 1998 .

[42]  G. Tucker,et al.  Drainage basin responses to climate change , 1997 .

[43]  W. Dietrich,et al.  The soil production function and landscape equilibrium , 1997, Nature.

[44]  Luc Ortlieb,et al.  Determining the Early History of El Niño , 1997 .

[45]  James W. Kirchner,et al.  Spatially Averaged Long-Term Erosion Rates Measured from in Situ-Produced Cosmogenic Nuclides in Alluvial Sediment , 1996, The Journal of Geology.

[46]  P. Bierman,et al.  ESTIMATING RATES OF DENUDATION USING COSMOGENIC ISOTOPE ABUNDANCES IN SEDIMENT , 1996 .

[47]  M. Summerfield,et al.  Natural controls of fluvial denudation rates in major world drainage basins , 1994 .

[48]  K. Nishiizumi,et al.  Chemical isolation of quartz for measurement of in-situ-produced cosmogenic nuclides , 1992 .

[49]  B. Isacks.  Uplift of the Central Andean Plateau and bending of the Bolivian orocline , 1988 .

[50]  C. Laj,et al.  An accreted continental terrane in northwestern Perú , 1988 .

[51]  V. Neal,et al.  El Niño occurrences over the past four and a half centuries , 1987 .

[52]  J. Beer,et al.  10Be: Half-life and AMS-standards , 1987 .

[53]  E. Rasmusson,et al.  Variations in Tropical Sea Surface Temperature and Surface Wind Fields Associated with the Southern Oscillation/El Niño , 1982 .

[54]  N. Cox.  On the relationship between bedrock lowering and regolith thickness , 1980 .

[55]  J. Flint.  Stream gradient as a function of order, magnitude, and discharge , 1974 .

[56]  M. Wolman,et al.  Magnitude and Frequency of Forces in Geomorphic Processes , 1960, The Journal of Geology.

[57]  O. Korup.  Rock-slope failure and the river long profile , 2006 .

[58]  R. Stallard,et al.  Denudation rates determined from the accumulation of in situ-produced 10Be in the luquillo experimental forest, Puerto Rico , 1995 .

[59]  J. Caldas,et al.  Geologia de los cuadrangulos de : las playas, la tina, las lomas, ayabaca, san antonio, chulucanas, morropon, huancabamba, olmos y pomahuaca , 1987 .

[60]  D. Sandweiss,et al.  The birth of El Niño: geoarchaeological evidence and implications , 1986 .

[61]  J. T. Hack,et al.  Stream-profile analysis and stream-gradient index , 1973 .