六盘山盆地热历史的裂变径迹证据

研究盆地的热历史将为确定生烃过程和探勘目标提供重要制约因素。磷灰石裂变径迹研究表明，六盘山盆地白垩系地层经历两次埋深加热事件。第一次在白垩经末之前达到最高古地温，第二次在晚新生代约8MaB.P.之前达到最高古地温.第一次最高古地温要高于第二次最高古地温.晚新生代六盘山盆地古地温梯度为16℃/km.从白垩纪到新生代,六盘山盆地可能发生古地温梯度降低事件.三叠纪、中侏罗统烃源岩达到或超过生油高峰温度.白垩纪乃家河组和马东山组虽然进入生油窗温度范围,但未达到生油峰温度.按照古地温资料推断,三叠纪、中侏罗统烃源岩应为六盘山盆地主要生烃源岩,晚白垩纪之前应为六盘山盆地烃源岩的主要生烃阶段.     

北京千家店地区侏罗系后城组磷灰石裂变径迹分析及其地质意义

运用裂变径迹分析方法, 探讨分析了千家店地区侏罗系后城组地层的构造热演化特征. 千家店地区后城组上段三个磷灰石样品,AFT年龄集中在85.7～76.0 Ma,小于其相应的地层年龄;平均封闭径迹长度为9.4～10.8 μm,小于初始径迹长度(16.3±0.9 μm),呈非对称的单峰态分布,标准偏差为2.1～2.5. 后城组下段的三个AFT样品,AFT年龄集中在82.6～62.4 Ma,小于其相应的地层年龄,也小于上段层位的AFT年龄;平均封闭径迹长度仅为7.2～7.7 μm,远小于初始径迹长度(16.3±0.9 μm),其中YQ-07样品的封闭径迹长度呈似双峰态分布,标准偏差达到3.1;显然,侏罗系样品经历了明显的中度退火行为,最大温度可能接近于90℃. AFT年龄和封闭径迹长度的规律性变化主要是由于埋深不同引起的温度差异造成的. 裂变径迹热历史模拟结果表明,沉积物自进入盆地充填埋藏一直到115 Ma左右,盆地沉积物达到最大埋深3000多米,盆地温度达到最大值90℃多,这一过程沉积速率达到66.7 m/Ma. 115 Ma之后盆地处于相对稳定期,没有明显的温度波动,直到6 Ma左右温度以11.7 ℃/Ma的速度突然下降,表明侏罗系地层遭受剥蚀,迅速上升、快速冷却直至地表,剥露速率超过了500 m/Ma.     

Constraining the stepwise migration of the eastern Tibetan Plateau margin by apatite fission track thermochronology

Granites sampled from Garzê-Litang thrust, Longmen Shan thrust, Garzê and Litang strike-slip faults in the eastern Tibetan Plateau have been analyzed with apatite fission track thermochronological method in this study. The measured fission track apparent ages, combined with the simulated annealing mod- eling of the thermal history, have been used to reconstruct the thermal evolutionary histories of the samples and interpret the active history of the thrusts and faults in these areas. Thermal history mod- eling shows that earlier tectonic cooling occurred in the Garzê-Litang thrust in Miocene (~20―16 Ma) whereas the later cooling occurred mainly in the Longmen Shan thrust since ~5 Ma. Our study sug- gests that the margin of eastern Tibetan Plateau was extended by stages: through strike-slip faults deformations and related thrusts, the upper crust formed the Garzê-Litang margin in the Miocene epoch and then moved to the Longmen Shan margin since ~5 Ma. During this process, the deformations of different phases in the eastern Tibetan Plateau were absorbed by the thrusts within them and conse- quently the tectonic events of long-distance slip and extrusion up to hundreds of kilometers have not been found.     

Fission track dating of the Cenozoic uplift in Mabian area, southern Sichuan Province, China

The apparent ages of samples are obtained from fission track dating of apatite samples collected from the fault zones in Mabian area, southern Sichuan Province. In addition, thermal history is simulated from the obtained data by applying AFT Solve Program, to acquire the thermal evolution history of the samples. The result shows that tectonically the Mabian area was relatively stable between 25 and 3 Ma, compared to the inner parts and other marginal areas of the Tibetan Plateau. The studied area had little response to the rapid uplift events that occurred for several times in the Tibetan Plateau during 25-3 Ma. The latest thermal event related to the activity of the Lidian fault zone (about 8 Ma ) is later than that of the Ebian fault zone (18-15 Ma ) to the west, indicating to some extent that the evolution of fault activity in the Mabian area has migrated from west to east. The latest extensive tectonic uplift occurred since about 3 Ma. As compared with the Xianshuihe fault zone, the Mabian area is closer to the east- ern margin of the plateau, while the time of fast cooling event in this area is later than that in the southeast segment of the Xianshuihe fault zone (3.6-3.46 Ma ). It appears to support the assumption of episodic uplift and stepwise outward extension of the eastern boundary of the Tibetan Plateau in late Cenozoic.     

Postcrystallization thermal evolution history of Gangdese batholithic zone and its tectonic implication

Using cooling curves of K-feldspars obtained by using specific⁴⁰Ar/³⁹Ar stepe heating procedure and multiple diffusion domain modeling (MDD model), together with results of dating hornblends, biotite, and apatite, further work has been done to examine the characteristics of the postcrystallization thermal evolution history of Gangdese batholithic zone, to compare the starting times of rapid cooling events with the variation regularities of apatite fission track (FT) ages in the eastern and western parts of Gangdese batholithic zone, and to provide the evidence for mass transport and energy transfers in the lithosphere after the collision between Indian and Eurasian plates. Project supported by the National Natural Science Foundation of China (Grant No. 49473171).     

贡嘎山快速隆升的磷灰石裂变径迹证据及其隆升机制讨论

鲜水河断裂是青藏高原东南缘的一条北西向大型左旋走滑断裂,其南东段逐渐向南偏转,并与近南北向的安宁河断裂相接,在两个断裂相接处西侧耸立着海拔7556 m高的贡嘎山.磷灰石裂变径迹(AFT)测试可知,贡嘎山及其邻区12个样品的年龄分布在0.2±0.1 Ma~2.7±0.7 Ma之间,平均径迹长度在13.64~15.19 μm之间,表明贡嘎山及其邻区第四纪时期一直处于快速剥蚀状态.结合前人在此地区的低温热年代研究成果,揭示出两个现象:(1)贡嘎山岩体及鲜水河断裂与龙门山断裂所夹的三角区域为快速隆升区域,而其西侧、北侧的高原腹地的隆升速率远低于这两个区域;(2)贡嘎山岩体从北向南隆升速率逐渐变大,其最南端1 Ma以来的隆升速率超过3.3±0.8 mm/a.这些现象表明青藏高原在整体横向挤出、缓慢隆升的基础上,还存在着一些特殊的局部快速隆升区域.通过对川滇地块水平运动的矢量分解,我们认为贡嘎山花岗岩体是鲜水河断裂至安宁河断裂间挤压弯曲段吸收、转换川滇地块南东向水平运动导致局部快速隆升的产物,在这一过程中,由于垂直于断裂的挤压分量从北到南逐渐增大,导致了岩体从北往南的隆升速率逐渐增大.     

磷灰石裂变径迹退火动力学模型研究进展综述

裂变径迹退火过程是非线性动力学过程，在一系列磷灰石裂变径迹室内退火实验基础上，研究者提出许多经验退火模型，其中扇型模型与实验数据拟合最好，多组分退火模型将扇型模型的应用扩展到复杂物源成分的磷灰石，理论物理退火模型建立在原子尺度动力机制上，并经由实验数据确定具物理意义的未知参数，目前还不如经验模型成功，室内退火实验表明除了温度、受热时间，退火行为与磷灰石的化学成分，径迹与结晶c轴的方位关系、由Dpar定量表征的颗粒溶蚀度等因素有密切关系。     

Late stage thermal history of the Songliao Basin and its tectonic implications: Evidence from apatite fission track (AFT) analyses

Apatite Fission Track (AFT) data from the Songliao Basin indicates that the late stage tectonic movements in the Songliao Basin have zoning in space and episodes in time. The late stage tectonic movements started from the east part of the basin and migrated westward. AFT ages in the east part of the basin are older than those in the west part of the basin, suggesting that the uplift occurred earlier in the east than in the west. The denudation thickness in the east part of the basin is significantly greater than that in the centre and west. The thermal history evolved two episodes of rapid cooling and subsequent slow cooling processes. Age-depth relationship derived from the AFT data indicates a four-episode denudation history. Further Monte Carlo random simulation of the AFT data reveals the four changing points of the thermal evolution at 65 Ma, 43.5 Ma, 28 Ma and 15 Ma, respectively. The uplifting and denudation rates from different episodes of evolution are proportional to the plate convergence rate. Based on the above analyses and the regional geologic background, it is concluded that the late stage thermal events in the Songliao Basin are the far field response to the subduction of the Pacific Plate under the Eurasian Plate. The first episode of the rapid cooling probably started at the end of the Nenjiang Formation, climaxed at the end of the Cretaceous and ceased at the Late Eocene. The subsequent slow cooling lasts another 15 Ma. The first episode of the evolution is the far field response to the major episode of the Yanshan Movement and subsequent series of the tectonic reorganization, especially the directional change of the Pacific Movement and also the subduction of the Indian Plate underneath the Eurasian Plate. While the second episode of the evolution is the far field response to the extension and closure of the Sea of Japan. Extension led to the migration and converging of the mantle heat flow to the Sea of Japan and resulted in the rapid cooling of the Songliao Basin.     

应用裂变径迹不同模式约束岩体冷却史的初步探讨—以滇西独龙江岩体为例

在利用磷灰石裂变径迹热年代学方法来约束岩体冷却史的应用中,由于地质条件和磷灰石退火性质的限制,表观年龄往往不能直接代表特定地质事件的时间.利用封闭径迹的长度直方图模式和高程-年龄模式可定性地反映出岩体冷却史是否遭受过干扰.平均径迹长度-年龄(或香蕉图)模式、径迹年龄谱模式以及反演模拟在某种程度上可用来限定地质过程中冷却启动的时间.然而,对于多阶段的冷却史,模式和模拟分析的不确定性仍较显著,对早期时限的定量揭示仍是研究和应用中的一个难点.只有结合多种方法、模式和模拟的运用并考虑地质背景才能较清晰地约束岩体的冷却历史.     

秦岭太白山新生代隆升冷却历史的磷灰石裂变径迹分析

伸展正断层下盘的冷却历史记录了主要伸展变形的时间及幅度.太白山位于秦岭北缘,作为伸展正断层的下盘,其新生代伸展隆升冷却历史有助于我们更好地理解渭河盆地的伸展变形时间及其幅度.本文利用磷灰石裂变径迹分析方法对太白山的冷却历史进行了研究.来自太白山总计17个样品的磷灰石裂变径迹数据及热历史模拟揭示出山体经历了始于约48 Ma的小幅度快速抬升冷却阶段,和始于约9.6 Ma的大幅度快速抬升冷却阶段;分别对应平行于秦岭北缘山脉的两阶段伸展变形.始于约48 Ma的伸展变形可能是印度板块与欧亚板块碰撞作用在大陆内部的远场响应,而始于约9.6 Ma的快速伸展变形可能与青藏高原在该时期快速隆升和对外扩展有关.     

Thermo-tectonic history of Ryoke Basement in Hohi volcanic zone, northeast Kyushu, Japan: Constraints from fission track thermochronology

Abstract Apatite and zircon fission track ages from Ryoke Belt basement in northeast Kyushu show late Cretaceous, middle to late Eocene, middle Miocene and Quaternary groupings. The basement cooled through 240 ± 25°C, the closure temperature for fission tracks in zircon, mainly during the interval 74-90 Ma as a result of uplift and denudation, the pattern being uniform across northeast Kyushu. In combination with published K-Ar ages and the Turonian-Santonian age of sedimentation in the Onogawa Basin, active suturing along the Median Tectonic Line from 100-80 Ma, at least, is inferred. Ryoke Belt rocks along the northern margin of Hohi volcanic zone (HVZ) cooled rapidly through ∼100°C to less than 50°C during the middle Eocene to Oligocene, associated with 2.5-3.5 km of denudation. The timing of this cooling follows peak heating in the Eocene-Oligocene part (Murotohanto subbelt) of the Shimanto Belt in Muroto Peninsula (Shikoku) inferred previously, and coincides with the 43 Ma change in convergence direction of the Pacific-Eurasian plate and the demise of the Kula-Pacific spreading centre. Ryoke Belt rocks along the southern margin of HVZ have weighted mean apatite fission track ages of 15.3 ± 3.1 Ma. These reset ages are attributed to an increase in geothermal gradient in the middle Miocene combined with rapid denudation and uplift of at least 1.4 km. These ages indicate that heating of the overriding plate associated with the middle Miocene start of subduction of hot Shikoku Basin lithosphere extended into the Ryoke Belt in northeast Kyushu. Pleistocene apatite fission track ages from Ryoke Belt granites at depth in the centre of HVZ are due to modern annealing in a geothermal environment.     

合肥盆地构造热演化的裂变径迹证据

运用裂变径迹分析方法,探讨分析了合肥盆地中新生代的构造热演化特征. 上白垩统和古近系下段样品的磷灰石裂变径迹（AFT）数据主体表现为靠近部分退火带顶部温度(±65℃)有轻度退火,由此估算晚白垩世至古近纪早期合肥盆地断陷阶段的古地温梯度接近38℃/km,高于盆地现今地温梯度(27.5℃/km).下白垩统、侏罗系及二叠系样品的AFT年龄(97.5～2.5Ma)和锆石裂变径迹(ZFT)年龄(118～104Ma)均明显小于其相应的地层年龄,AFT年龄－深度分布呈现冷却型曲线形态,且由古部分退火带、冷却带或前完全退火带及其深部的今部分退火带组成,指示早白垩世的一次构造热事件和其随后的抬升冷却过程. 基于AFT曲线的温度分带模式和流体包裹体测温数据的综合约束,推算合肥盆地早白垩世走滑压陷阶段的古地温梯度接近67℃/km. 径迹年龄分布、AFT曲线拐点年龄和区域抬升剥蚀时间的对比分析结果表明,合肥盆地在早白垩世构造热事件之后的104Ma以来总体处于抬升冷却过程,后期快速抬升冷却事件主要发生在±55Ma.     

滇西临沧花岗岩基新生代剥蚀冷却的裂变径迹证据

为揭示临沧花岗岩基的剥蚀冷却历史,探讨印藏碰撞对滇西的影响,对6块临沧花岗岩基样品进行锆石和磷灰石裂变径迹测定,并利用模拟退火法对其中5块样品的磷灰石裂变径迹数据进行非线性热史反演,估算了不同时期的剥蚀量和抬升量. 结果表明,岩基自印藏陆陆碰撞以来经历了两期冷却事件,早期冷却速率仅5～10 ℃/Ma,晚期冷却速率明显增高,特别是近3 Ma以来的冷却速率达到16～20 ℃/Ma;两期总剥蚀厚度可达3300～3500 m. 分析表明冷却事件与印藏碰撞关系密切,早期冷却是在印藏碰撞影响下,临沧岩基卷入逆冲推覆运动而遭遇抬升、剥蚀的结果;晚期冷却则是上新世以来,特别是3Ma以来岩基经受整体的强烈抬升、剥蚀的结果,该期构造抬升量约为672～1263 m;裂变径迹资料还揭示印藏碰撞先影响南部岩体,随后才波及到岩基中北段.     

Thermal effects of Caledonian foreland basin formation,based on fission track analyses applied on basement rocks in central Sweden

Increasing evidence from fission track studies in Sweden indicate that large parts of the Fennoscandian Shield have been affected by a large-scale thermotectonic event in the Palaeozoic. In this study the results of 17 apatite fission track analyses from central Sweden are presented collected along three NW–SE transects trending from the Bothnian Sea to the Caledonides. On the Bothnian coast samples have been collected directly from the Sub-Cambrian Peneplain. The sedimentary cover protecting this surface until recently is responsible for the thermal increase detected through apatite fission track (FT) thermochronology.The apatite FT ages range between 516 ± 46 Ma (±1σ) on the Bothnian coast around sea level to 191 ± 11 Ma in the Caledonides (～500–1500 m.a.s.l.). The mean track lengths vary from 11.3 ± 2.2 μm (±1σ) in the east to 14.2 ± 2.8 μm in the west, indicating a longer stay in the PAZ in the east, versus a continuous cooling pattern in the west. This pattern in combination with other geological constraints indicates that the crystalline basement rocks near the Caledonian deformation front in the west experienced higher temperatures after the formation of the Sub-Cambrian Peneplain followed by denudation, compared with the basement rocks in the east near the Bothnian coast.The apatite FT data near the Caledonian deformation front indicates prevailing temperatures of more than 110 ± 10 °C prior to the Mid Palaeozoic, causing a resetting of the apatite fission track clock. The temperatures were progressively lower away from the deformation front. Apatite fission track analysis of samples collected from the Sub-Cambrian Peneplain along the Bothnian coast indicate maximum temperatures of 90 ± 15 °C during Late Silurian–Early Devonian time. This heating event is argued to be the result of burial beneath a developing foreland basin in front of the Caledonian orogeny. Assuming a geothermal gradient of 20 °C/km, this temperature increase can be converted to a total burial of the samples. The resulting geometry of this basin can be described as an asymmetrical basin at least 3.5 km deep in the vicinity of the Caledonian deformation front decreasing to about 2.5 km on the Bothnian coast, continuing further onto Finland. The width of this basin was in thus in the order of 600 km. Whether this was formed completely synorogenic or partly synorogenic, broadening after cessation of the orogeny, could not be revealed.The Late Palaeozoic and Mesozoic thermal evolution of this area is related to the extensional tectonics in the North Atlantic Domain.     

Variscan terrane of deep-crustal granulite facies in Yushugou area, southern Tianshan

The Yushugou terrane of deepcrustal granulite facies in southern Tianshan consists of two parts, granulite and metaperidotite. The whole terrane is a metamorphism of (high-pressure) grunulite facies, and typical mineral associations are: Gt-Cpx-P1-Tit-Ilm (±Qz) (silica-saturated and oversaturated mafic rocks), Gt-Ky (pseudomorph)-P1-Ru-Ilm± Qz (metapelitic rocks) and Spi-Opx-Cpx-01 (meta-ultramafic rocks). The peak-stage P-T conditions are 795— 964°, 0.97—1.42 GPa, which are obtained with mineral chemistry, assemblage analyses and P-T estimation. The Sm-Nd isochron age of peak-stage metamorphic minerals is (315 ± 3.62) Ma. All of these indicate that the terrane is a deep-crustal body, which subducts to the depth of 40—50 km in the middle late-Paleozoic, undergoing metamorphism of (high-pressure) granulite facies, and exhumed again to the surface by tectonic uplifting. Project supported hy the National Natural Science Foundation of China (Grant No. 49472135).     

川西坳陷鸭子河地区基于多种古温标的钻井热史恢复

利用镜质体反射率(Ro)、磷灰石裂变径迹(AFT)和伊利石结晶度(IC指数)等古温标恢复了四川盆地川西坳陷的钻井热史,对比了不同温标最高古地温的恢复结果.研究表明,研究区晚白垩世至今总体表现为冷却及抬升剥蚀的过程,地温梯度由约26 ℃·km-1降低至约22 ℃·km-1,剥蚀量约1.3~1.9 km.约80 Ma以来开始抬升剥蚀, 40—2.5 Ma经历了一个热平静期,第四纪存在一定的增温,地温梯度增高约5 ℃·km-1.三种古地温恢复结果具有较高的一致性,相对于镜质体反射率(Ro)和磷灰石裂变径迹(AFT)等成熟古温标,伊利石结晶度作为有机质成熟度指标和沉积岩古温标的应用处于定性分析阶段,该指标的热演化模型仍需进一步探索.     

Unravelling a long-term multi-event thermal record in the cratonic interior of southern Finland through apatite fission track thermochronology

Apatite fission track thermochronology (AFTT) has been applied to the Precambrian basement rocks of southern Finland in an attempt to detect within the long-term thermal history, thermal manifestations in the cratonic interior of tectonic events at the craton margin. The likely subtle magnitude of these manifestations means that AFTT is a useful technique for such a study due to its low temperature sensitivity. A total of 10 samples have been analysed, generating AFTT ages, length statistics and thermal models. Ages range from 313 ± 22 to 848 ± 60 Ma and mean track lengths range from 11.0 ± 1.6 to 13.3 ± 1.8 μm. The data suggests the presence of thermal overprinting of an earlier cooling event. Thermal modelling produces similar results for all samples and typically contains the following major events: (1) two phases of Late-Proterozoic cooling, (2) Late-Silurian re-heating, (3) Cenozoic cooling. The first phase of Late-Proterozoic cooling is interpreted to be due to aulacogen inversion as a result of stress propagation from the collisional tectonics of the Sveconorwegian orogeny. The second phase is discussed in relation to passive margin formation and possible asthenospheric diaper induced relief and exhumation. The Late-Silurian re-heating coincides in time with a proposed Caledonian foreland basin. The Cenozoic cooling is interpreted to represent the latest exposure resulting from North Atlantic Margin formation induced uplift and associated denudation.     

羌塘中央隆起带深部结构特征研究及其意义

羌塘含油气盆地是我国境内最大的中新生代海相沉积盆地.羌塘地体内的中央隆起将盆地分为南北两个盆地.中央隆起带构造属性认识存在两种截然不同的分歧,一是伸展环境下形成,整个羌塘盆地有着同一的基底.而另一认识其是一古特提斯缝合带,其两侧盆地具有不同的演化机制.调查羌塘中央隆起的深部结构特征及其与南北两侧的盆地间的构造关系是认识羌塘盆地基底性质及其油气远景之关键科学问题.尽管羌塘地体在青藏高原形成演化过程中遭到了强烈改造,但在收集并分析已有地球物理资料基础上认为其深部结构仍有可能被完整保存.因此,利用密集宽频带流动台网观测,获取其深部结构,进而研究其与两侧盆地关系,是当前羌塘含油气盆地研究之重要突破口,同时该项研究符合我国当前国家油气资源战略评估政策.     

New progresses on geothermal history of Turpan-Hami Basin, Xinjiang, China

A comprehensive study on geothermal history of the Turpan-Hami Basin by vitrinite reflectance, fluid inclusion geothermometry, apatite fission track and⁴⁰Ar-³⁹Ar dating displays that the main effects influencing geotemperature distribution are burial depth of the basement, heat flow, magmatic activities, as well as tectonic movement, having a rugulation to be higher in the east and north, lower in the west and south, as well as higher in the past and lower at the present. The heat of the mantle source and the Indo-China tectonic thermal event have extremely influenced maturation of source rocks of the upper Lower Permian and the Middle and Upper Triassic in the lndo-China epoch. While, the geothermal gradient and the weak tectonic geothermal event of the Early Yanshan Movement provided necessary heat for the maturation of source rock in coal-bearing strata of the Middle and Lower Jurassic.     

Quantitative relationships between uplift and relief parameters for the Southern Alps,New Zealand,as determined by fission track analysis

The Southern Alps mountain chain, New Zealand, has formed as a consequence of late Cenozoic collision of the continental parts of the Pacific and Australia plates. Fission track analysis has yielded estimates of the amount, age of initiation, and rate of late Cenozoic rock uplift for 82 surface samples taken from transects across the Southern Alps. The mean surface, summit and valley elevations in the vicinity of each of the rock sample sites have also been measured. Regression of the geomorphic variables on the uplift variables has been used to establish quantitative relationships between uplift and geomorphology. There are strong and consistent linear associations between uplift and the elevations of the mean surface, summits and valleys. The preferred regression models have uniform slope but varying elevation response between transects. Substitution of space for time has allowed the evolution of landforms to be studied. To the east of the Main Divide, elevation and relief are proportional to, and closely related to, the age of initiation of rock uplift (‘uplift age’) and the amount of rock uplift (r² > 0·8). Mean surface uplift was delayed for ～2 Ma after the start of rock uplift, a result of the stripping of a soft cover rock succession that, prior to rock uplift, overlaid the harder greywacke basement. Inter-transect variations in regression response and x-intercept are inferred, therefore, to reflect the variable preuplift thickness of cover rocks. However, the regular regression slope for the transects reflects the consistent nature of the interaction between uplift and the erodibility of greywacke basement. Uplift of the mean surface proceeded at 0·4 km/km and 0·4 km/Ma of rock uplift, while the rock uplift rate was 0·8 km/Ma. Summit elevations have increased at a rate of 0·6 km/Ma and valley elevations have increased at 0·2 km/Ma. Regression lines relating mean surface, summit and valley elevations to rock uplift and uplift age diverge from common intercepts; it is concluded, therefore, that the mountains east of the Main Divide have continued to increase in elevation and relief and change in form over time since the start of mean surface uplift. Mountain elevation has little relationship with late Cenozoic mean rock uplift rates of 0·8–1·0 km/Ma or inferred contemporary rock uplift rates (r² ～ 0·3). In contrast, to the west of the Main Divide, elevation is shown to be closely related to rock uplift rate (r² > 0·3). In contrast, to the west of the Main Divide, elevation is shown to be closely related to rock uplift rate (r² > 0·8). Transects with higher rock uplift rates support higher topography. Landforms are therefore in a stable equilibrium with rock uplift rate, and the landscape contains no residual evidence of the total amount of rock uplift, or the age of uplift. Lithological variation appears to have no relationship with elevation.